rfc9635.original   rfc9635.txt 
GNAP J. Richer, Ed. Internet Engineering Task Force (IETF) J. Richer, Ed.
Internet-Draft Bespoke Engineering Request for Comments: 9635 Bespoke Engineering
Intended status: Standards Track F. Imbault Category: Standards Track F. Imbault
Expires: 10 September 2024 acert.io ISSN: 2070-1721 acert.io
9 March 2024 September 2024
Grant Negotiation and Authorization Protocol Grant Negotiation and Authorization Protocol (GNAP)
draft-ietf-gnap-core-protocol-19
Abstract Abstract
GNAP defines a mechanism for delegating authorization to a piece of The Grant Negotiation and Authorization Protocol (GNAP) defines a
software, and conveying the results and artifacts of that delegation mechanism for delegating authorization to a piece of software and
to the software. This delegation can include access to a set of APIs conveying the results and artifacts of that delegation to the
as well as subject information passed directly to the software. software. This delegation can include access to a set of APIs as
well as subject information passed directly to the software.
Status of This Memo Status of This Memo
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7 1.1. Terminology
1.2. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2. Roles
1.3. Elements . . . . . . . . . . . . . . . . . . . . . . . . 10 1.3. Elements
1.4. Trust relationships . . . . . . . . . . . . . . . . . . . 11 1.4. Trust Relationships
1.5. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 13 1.5. Protocol Flow
1.6. Sequences . . . . . . . . . . . . . . . . . . . . . . . . 16 1.6. Sequences
1.6.1. Overall Protocol Sequence . . . . . . . . . . . . . . 16 1.6.1. Overall Protocol Sequence
1.6.2. Redirect-based Interaction . . . . . . . . . . . . . 19 1.6.2. Redirect-Based Interaction
1.6.3. User-code Interaction . . . . . . . . . . . . . . . . 22 1.6.3. User Code Interaction
1.6.4. Asynchronous Authorization . . . . . . . . . . . . . 25 1.6.4. Asynchronous Authorization
1.6.5. Software-only Authorization . . . . . . . . . . . . . 27 1.6.5. Software-Only Authorization
1.6.6. Refreshing an Expired Access Token . . . . . . . . . 28 1.6.6. Refreshing an Expired Access Token
1.6.7. Requesting Subject Information Only . . . . . . . . . 30 1.6.7. Requesting Subject Information Only
1.6.8. Cross-User Authentication . . . . . . . . . . . . . . 31 1.6.8. Cross-User Authentication
2. Requesting Access . . . . . . . . . . . . . . . . . . . . . . 34 2. Requesting Access
2.1. Requesting Access to Resources . . . . . . . . . . . . . 36 2.1. Requesting Access to Resources
2.1.1. Requesting a Single Access Token . . . . . . . . . . 36 2.1.1. Requesting a Single Access Token
2.1.2. Requesting Multiple Access Tokens . . . . . . . . . . 39 2.1.2. Requesting Multiple Access Tokens
2.2. Requesting Subject Information . . . . . . . . . . . . . 41 2.2. Requesting Subject Information
2.3. Identifying the Client Instance . . . . . . . . . . . . . 42 2.3. Identifying the Client Instance
2.3.1. Identifying the Client Instance by Reference . . . . 44 2.3.1. Identifying the Client Instance by Reference
2.3.2. Providing Displayable Client Instance Information . . 45 2.3.2. Providing Displayable Client Instance Information
2.3.3. Authenticating the Client Instance . . . . . . . . . 45 2.3.3. Authenticating the Client Instance
2.4. Identifying the User . . . . . . . . . . . . . . . . . . 46 2.4. Identifying the User
2.4.1. Identifying the User by Reference . . . . . . . . . . 47 2.4.1. Identifying the User by Reference
2.5. Interacting with the User . . . . . . . . . . . . . . . . 48 2.5. Interacting with the User
2.5.1. Start Mode Definitions . . . . . . . . . . . . . . . 50 2.5.1. Start Mode Definitions
2.5.2. Interaction Finish Methods . . . . . . . . . . . . . 52 2.5.2. Interaction Finish Methods
2.5.3. Hints . . . . . . . . . . . . . . . . . . . . . . . . 55 2.5.3. Hints
3. Grant Response . . . . . . . . . . . . . . . . . . . . . . . 56 3. Grant Response
3.1. Request Continuation . . . . . . . . . . . . . . . . . . 58 3.1. Request Continuation
3.2. Access Tokens . . . . . . . . . . . . . . . . . . . . . . 59 3.2. Access Tokens
3.2.1. Single Access Token . . . . . . . . . . . . . . . . . 59 3.2.1. Single Access Token
3.2.2. Multiple Access Tokens . . . . . . . . . . . . . . . 63 3.2.2. Multiple Access Tokens
3.3. Interaction Modes . . . . . . . . . . . . . . . . . . . . 64 3.3. Interaction Modes
3.3.1. Redirection to an arbitrary URI . . . . . . . . . . . 66 3.3.1. Redirection to an Arbitrary URI
3.3.2. Launch of an application URI . . . . . . . . . . . . 66 3.3.2. Launch of an Application URI
3.3.3. Display of a Short User Code . . . . . . . . . . . . 67 3.3.3. Display of a Short User Code
3.3.4. Display of a Short User Code and URI . . . . . . . . 68 3.3.4. Display of a Short User Code and URI
3.3.5. Interaction Finish . . . . . . . . . . . . . . . . . 69 3.3.5. Interaction Finish
3.4. Returning Subject Information . . . . . . . . . . . . . . 69 3.4. Returning Subject Information
3.4.1. Assertion Formats . . . . . . . . . . . . . . . . . . 71 3.4.1. Assertion Formats
3.5. Returning a Dynamically-bound Client Instance 3.5. Returning a Dynamically Bound Client Instance Identifier
Identifier . . . . . . . . . . . . . . . . . . . . . . . 72 3.6. Error Response
3.6. Error Response . . . . . . . . . . . . . . . . . . . . . 72 4. Determining Authorization and Consent
4.1. Starting Interaction with the End User
4. Determining Authorization and Consent . . . . . . . . . . . . 74 4.1.1. Interaction at a Redirected URI
4.1. Starting Interaction With the End User . . . . . . . . . 79 4.1.2. Interaction at the Static User Code URI
4.1.1. Interaction at a Redirected URI . . . . . . . . . . . 79 4.1.3. Interaction at a Dynamic User Code URI
4.1.2. Interaction at the Static User Code URI . . . . . . . 80 4.1.4. Interaction through an Application URI
4.1.3. Interaction at a Dynamic User Code URI . . . . . . . 81 4.2. Post-Interaction Completion
4.1.4. Interaction through an Application URI . . . . . . . 83
4.2. Post-Interaction Completion . . . . . . . . . . . . . . . 83
4.2.1. Completing Interaction with a Browser Redirect to the 4.2.1. Completing Interaction with a Browser Redirect to the
Callback URI . . . . . . . . . . . . . . . . . . . . 84 Callback URI
4.2.2. Completing Interaction with a Direct HTTP Request 4.2.2. Completing Interaction with a Direct HTTP Request
Callback . . . . . . . . . . . . . . . . . . . . . . 85 Callback
4.2.3. Calculating the interaction hash . . . . . . . . . . 86 4.2.3. Calculating the Interaction Hash
5. Continuing a Grant Request . . . . . . . . . . . . . . . . . 87 5. Continuing a Grant Request
5.1. Continuing After a Completed Interaction . . . . . . . . 90 5.1. Continuing after a Completed Interaction
5.2. Continuing During Pending Interaction (Polling) . . . . . 92 5.2. Continuing during Pending Interaction (Polling)
5.3. Modifying an Existing Request . . . . . . . . . . . . . . 94 5.3. Modifying an Existing Request
5.4. Revoking a Grant Request . . . . . . . . . . . . . . . . 100 5.4. Revoking a Grant Request
6. Token Management . . . . . . . . . . . . . . . . . . . . . . 101 6. Token Management
6.1. Rotating the Access Token Value . . . . . . . . . . . . . 102 6.1. Rotating the Access Token Value
6.1.1. Binding a New Key to the Rotated Access Token . . . . 104 6.1.1. Binding a New Key to the Rotated Access Token
6.2. Revoking the Access Token . . . . . . . . . . . . . . . . 105 6.2. Revoking the Access Token
7. Securing Requests from the Client Instance . . . . . . . . . 106 7. Securing Requests from the Client Instance
7.1. Key Formats . . . . . . . . . . . . . . . . . . . . . . . 107 7.1. Key Formats
7.1.1. Key References . . . . . . . . . . . . . . . . . . . 108 7.1.1. Key References
7.1.2. Key Protection . . . . . . . . . . . . . . . . . . . 109 7.1.2. Key Protection
7.2. Presenting Access Tokens . . . . . . . . . . . . . . . . 109 7.2. Presenting Access Tokens
7.3. Proving Possession of a Key with a Request . . . . . . . 110 7.3. Proving Possession of a Key with a Request
7.3.1. HTTP Message Signatures . . . . . . . . . . . . . . . 114 7.3.1. HTTP Message Signatures
7.3.2. Mutual TLS . . . . . . . . . . . . . . . . . . . . . 121 7.3.2. Mutual TLS
7.3.3. Detached JWS . . . . . . . . . . . . . . . . . . . . 124 7.3.3. Detached JWS
7.3.4. Attached JWS . . . . . . . . . . . . . . . . . . . . 128 7.3.4. Attached JWS
8. Resource Access Rights . . . . . . . . . . . . . . . . . . . 133 8. Resource Access Rights
8.1. Requesting Resources By Reference . . . . . . . . . . . . 137 8.1. Requesting Resources by Reference
9. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 140 9. Discovery
9.1. RS-first Method of AS Discovery . . . . . . . . . . . . . 141 9.1. RS-First Method of AS Discovery
9.2. Dynamic grant endpoint discovery . . . . . . . . . . . . 143 9.2. Dynamic Grant Endpoint Discovery
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 144 10. IANA Considerations
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 144 10.1. HTTP Authentication Scheme Registration
11.1. HTTP Authentication Scheme Registration . . . . . . . . 145 10.2. Media Type Registration
11.2. Media Type Registration . . . . . . . . . . . . . . . . 145 10.2.1. application/gnap-binding-jwsd
11.3. GNAP Grant Request Parameters . . . . . . . . . . . . . 149 10.2.2. application/gnap-binding-jws
11.3.1. Registration Template . . . . . . . . . . . . . . . 149 10.2.3. application/gnap-binding-rotation-jwsd
11.3.2. Initial Contents . . . . . . . . . . . . . . . . . . 149 10.2.4. application/gnap-binding-rotation-jws
11.4. GNAP Access Token Flags . . . . . . . . . . . . . . . . 150 10.3. GNAP Grant Request Parameters
11.4.1. Registration Template . . . . . . . . . . . . . . . 150 10.3.1. Registration Template
11.4.2. Initial Contents . . . . . . . . . . . . . . . . . . 151 10.3.2. Initial Contents
11.5. GNAP Subject Information Request Fields . . . . . . . . 151 10.4. GNAP Access Token Flags
11.5.1. Registration Template . . . . . . . . . . . . . . . 151 10.4.1. Registration Template
11.5.2. Initial Contents . . . . . . . . . . . . . . . . . . 152 10.4.2. Initial Contents
11.6. GNAP Assertion Formats . . . . . . . . . . . . . . . . . 152 10.5. GNAP Subject Information Request Fields
11.6.1. Registration Template . . . . . . . . . . . . . . . 152 10.5.1. Registration Template
11.6.2. Initial Contents . . . . . . . . . . . . . . . . . . 152 10.5.2. Initial Contents
11.7. GNAP Client Instance Fields . . . . . . . . . . . . . . 153 10.6. GNAP Assertion Formats
11.7.1. Registration Template . . . . . . . . . . . . . . . 153 10.6.1. Registration Template
11.7.2. Initial Contents . . . . . . . . . . . . . . . . . . 153 10.6.2. Initial Contents
11.8. GNAP Client Instance Display Fields . . . . . . . . . . 154 10.7. GNAP Client Instance Fields
11.8.1. Registration Template . . . . . . . . . . . . . . . 154 10.7.1. Registration Template
11.8.2. Initial Contents . . . . . . . . . . . . . . . . . . 154 10.7.2. Initial Contents
11.9. GNAP Interaction Start Modes . . . . . . . . . . . . . . 155 10.8. GNAP Client Instance Display Fields
11.9.1. Registration Template . . . . . . . . . . . . . . . 155 10.8.1. Registration Template
11.9.2. Initial Contents . . . . . . . . . . . . . . . . . . 156 10.8.2. Initial Contents
11.10. GNAP Interaction Finish Methods . . . . . . . . . . . . 156 10.9. GNAP Interaction Start Modes
11.10.1. Registration Template . . . . . . . . . . . . . . . 156 10.9.1. Registration Template
11.10.2. Initial Contents . . . . . . . . . . . . . . . . . 157 10.9.2. Initial Contents
11.11. GNAP Interaction Hints . . . . . . . . . . . . . . . . . 157 10.10. GNAP Interaction Finish Methods
11.11.1. Registration Template . . . . . . . . . . . . . . . 157 10.10.1. Registration Template
11.11.2. Initial Contents . . . . . . . . . . . . . . . . . 157 10.10.2. Initial Contents
11.12. GNAP Grant Response Parameters . . . . . . . . . . . . . 158 10.11. GNAP Interaction Hints
11.12.1. Registration Template . . . . . . . . . . . . . . . 158 10.11.1. Registration Template
11.12.2. Initial Contents . . . . . . . . . . . . . . . . . 158 10.11.2. Initial Contents
11.13. GNAP Interaction Mode Responses . . . . . . . . . . . . 159 10.12. GNAP Grant Response Parameters
11.13.1. Registration Template . . . . . . . . . . . . . . . 159 10.12.1. Registration Template
11.13.2. Initial Contents . . . . . . . . . . . . . . . . . 159 10.12.2. Initial Contents
11.14. GNAP Subject Information Response Fields . . . . . . . . 160 10.13. GNAP Interaction Mode Responses
11.14.1. Registration Template . . . . . . . . . . . . . . . 160 10.13.1. Registration Template
11.14.2. Initial Contents . . . . . . . . . . . . . . . . . 160 10.13.2. Initial Contents
11.15. GNAP Error Codes . . . . . . . . . . . . . . . . . . . . 161 10.14. GNAP Subject Information Response Fields
11.15.1. Registration Template . . . . . . . . . . . . . . . 161 10.14.1. Registration Template
11.15.2. Initial Contents . . . . . . . . . . . . . . . . . 161 10.14.2. Initial Contents
11.16. GNAP Key Proofing Methods . . . . . . . . . . . . . . . 162 10.15. GNAP Error Codes
11.16.1. Registration Template . . . . . . . . . . . . . . . 162 10.15.1. Registration Template
11.16.2. Initial Contents . . . . . . . . . . . . . . . . . 163 10.15.2. Initial Contents
11.17. GNAP Key Formats . . . . . . . . . . . . . . . . . . . . 163 10.16. GNAP Key Proofing Methods
11.17.1. Registration Template . . . . . . . . . . . . . . . 163 10.16.1. Registration Template
11.17.2. Initial Contents . . . . . . . . . . . . . . . . . 164 10.16.2. Initial Contents
11.18. GNAP Authorization Server Discovery Fields . . . . . . . 164 10.17. GNAP Key Formats
11.18.1. Registration Template . . . . . . . . . . . . . . . 164 10.17.1. Registration Template
11.18.2. Initial Contents . . . . . . . . . . . . . . . . . 165 10.17.2. Initial Contents
12. Implementation Status . . . . . . . . . . . . . . . . . . . . 165 10.18. GNAP Authorization Server Discovery Fields
13. Security Considerations . . . . . . . . . . . . . . . . . . . 166 10.18.1. Registration Template
13.1. TLS Protection in Transit . . . . . . . . . . . . . . . 166 10.18.2. Initial Contents
13.2. Signing Requests from the Client Software . . . . . . . 167 11. Security Considerations
13.3. MTLS Message Integrity . . . . . . . . . . . . . . . . . 169 11.1. TLS Protection in Transit
13.4. MTLS Deployment Patterns . . . . . . . . . . . . . . . . 169 11.2. Signing Requests from the Client Software
13.5. Protection of Client Instance Key Material . . . . . . . 170 11.3. MTLS Message Integrity
13.6. Protection of Authorization Server . . . . . . . . . . . 171 11.4. MTLS Deployment Patterns
13.7. Symmetric and Asymmetric Client Instance Keys . . . . . 172 11.5. Protection of Client Instance Key Material
13.8. Generation of Access Tokens . . . . . . . . . . . . . . 173 11.6. Protection of Authorization Server
13.9. Bearer Access Tokens . . . . . . . . . . . . . . . . . . 174 11.7. Symmetric and Asymmetric Client Instance Keys
13.10. Key-Bound Access Tokens . . . . . . . . . . . . . . . . 175 11.8. Generation of Access Tokens
13.11. Exposure of End-user Credentials to Client Instance . . 176 11.9. Bearer Access Tokens
13.12. Mixing Up Authorization Servers . . . . . . . . . . . . 177 11.10. Key-Bound Access Tokens
13.13. Processing of Client-Presented User Information . . . . 177 11.11. Exposure of End-User Credentials to Client Instance
13.14. Client Instance Pre-registration . . . . . . . . . . . . 178 11.12. Mixing Up Authorization Servers
13.15. Client Instance Impersonation . . . . . . . . . . . . . 180 11.13. Processing of Client-Presented User Information
13.16. Client-Hosted Logo URI . . . . . . . . . . . . . . . . . 180 11.14. Client Instance Pre-registration
13.17. Interception of Information in the Browser . . . . . . . 181 11.15. Client Instance Impersonation
13.18. Callback URI Manipulation . . . . . . . . . . . . . . . 181 11.16. Client-Hosted Logo URI
13.19. Redirection Status Codes . . . . . . . . . . . . . . . . 182 11.17. Interception of Information in the Browser
13.20. Interception of Responses from the AS . . . . . . . . . 183 11.18. Callback URI Manipulation
13.21. Key Distribution . . . . . . . . . . . . . . . . . . . . 183 11.19. Redirection Status Codes
13.22. Key Rotation Policy . . . . . . . . . . . . . . . . . . 184 11.20. Interception of Responses from the AS
13.23. Interaction Finish Modes and Polling . . . . . . . . . . 185 11.21. Key Distribution
13.24. Session Management for Interaction Finish Methods . . . 185 11.22. Key Rotation Policy
13.25. Calculating Interaction Hash . . . . . . . . . . . . . . 187 11.23. Interaction Finish Modes and Polling
13.26. Storage of Information During Interaction and 11.24. Session Management for Interaction Finish Methods
Continuation . . . . . . . . . . . . . . . . . . . . . 189 11.25. Calculating Interaction Hash
13.27. Denial of Service (DoS) through Grant Continuation . . . 190 11.26. Storage of Information during Interaction and Continuation
13.28. Exhaustion of Random Value Space . . . . . . . . . . . . 191 11.27. Denial of Service (DoS) through Grant Continuation
13.29. Front-channel URIs . . . . . . . . . . . . . . . . . . . 191 11.28. Exhaustion of Random Value Space
13.30. Processing Assertions . . . . . . . . . . . . . . . . . 192 11.29. Front-Channel URIs
13.31. Stolen Token Replay . . . . . . . . . . . . . . . . . . 193 11.30. Processing Assertions
13.32. Self-contained Stateless Access Tokens . . . . . . . . . 194 11.31. Stolen Token Replay
13.33. Network Problems and Token and Grant Management . . . . 195 11.32. Self-Contained Stateless Access Tokens
13.34. Server-side Request Forgery (SSRF) . . . . . . . . . . . 196 11.33. Network Problems and Token and Grant Management
13.35. Multiple Key Formats . . . . . . . . . . . . . . . . . . 197 11.34. Server-Side Request Forgery (SSRF)
13.36. Asynchronous Interactions . . . . . . . . . . . . . . . 198 11.35. Multiple Key Formats
13.37. Compromised RS . . . . . . . . . . . . . . . . . . . . . 199 11.36. Asynchronous Interactions
13.38. AS-Provided Token Keys . . . . . . . . . . . . . . . . . 199 11.37. Compromised RS
14. Privacy Considerations . . . . . . . . . . . . . . . . . . . 200 11.38. AS-Provided Token Keys
14.1. Surveillance . . . . . . . . . . . . . . . . . . . . . . 200 12. Privacy Considerations
14.1.1. Surveillance by the Client . . . . . . . . . . . . . 200 12.1. Surveillance
14.1.2. Surveillance by the Authorization Server . . . . . . 201 12.1.1. Surveillance by the Client
14.2. Stored Data . . . . . . . . . . . . . . . . . . . . . . 201 12.1.2. Surveillance by the Authorization Server
14.3. Intrusion . . . . . . . . . . . . . . . . . . . . . . . 202 12.2. Stored Data
14.4. Correlation . . . . . . . . . . . . . . . . . . . . . . 202 12.3. Intrusion
14.4.1. Correlation by Clients . . . . . . . . . . . . . . . 202 12.4. Correlation
14.4.2. Correlation by Resource Servers . . . . . . . . . . 203 12.4.1. Correlation by Clients
14.4.3. Correlation by Authorization Servers . . . . . . . . 204 12.4.2. Correlation by Resource Servers
14.5. Disclosure in Shared References . . . . . . . . . . . . 204 12.4.3. Correlation by Authorization Servers
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 204 12.5. Disclosure in Shared References
15.1. Normative References . . . . . . . . . . . . . . . . . . 204 13. References
15.2. Informative References . . . . . . . . . . . . . . . . . 206 13.1. Normative References
Appendix A. Document History . . . . . . . . . . . . . . . . . . 209 13.2. Informative References
Appendix B. Compared to OAuth 2.0 . . . . . . . . . . . . . . . 215 Appendix A. Comparison with OAuth 2.0
Appendix C. Example Protocol Flows . . . . . . . . . . . . . . . 217 Appendix B. Example Protocol Flows
C.1. Redirect-Based User Interaction . . . . . . . . . . . . . 218 B.1. Redirect-Based User Interaction
C.2. Secondary Device Interaction . . . . . . . . . . . . . . 221 B.2. Secondary Device Interaction
C.3. No User Involvement . . . . . . . . . . . . . . . . . . . 224 B.3. No User Involvement
C.4. Asynchronous Authorization . . . . . . . . . . . . . . . 225 B.4. Asynchronous Authorization
C.5. Applying OAuth 2.0 Scopes and Client IDs . . . . . . . . 229 B.5. Applying OAuth 2.0 Scopes and Client IDs
Appendix D. Interoperability Profiles . . . . . . . . . . . . . 230 Appendix C. Interoperability Profiles
D.1. Web-based Redirection . . . . . . . . . . . . . . . . . . 231 C.1. Web-Based Redirection
D.2. Secondary Device . . . . . . . . . . . . . . . . . . . . 231 C.2. Secondary Device
Appendix E. Guidance for Extensions . . . . . . . . . . . . . . 232 Appendix D. Guidance for Extensions
Appendix F. JSON Structures and Polymorphism . . . . . . . . . . 233 Appendix E. JSON Structures and Polymorphism
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 234 Acknowledgements
Authors' Addresses
1. Introduction 1. Introduction
This protocol allows a piece of software, the client instance, to GNAP allows a piece of software, the client instance, to request
request delegated authorization to resource servers and subject delegated authorization to resource servers and subject information.
information. The delegated access to the resource server can be used The delegated access to the resource server can be used by the client
by the client instance to access resources and APIs on behalf a instance to access resources and APIs on behalf a resource owner, and
resource owner, and delegated access to subject information can in delegated access to subject information can in turn be used by the
turn be used by the client instance to make authentication decisions. client instance to make authentication decisions. This delegation is
This delegation is facilitated by an authorization server usually on facilitated by an authorization server, usually on behalf of a
behalf of a resource owner. The end user operating the software can resource owner. The end user operating the software can interact
interact with the authorization server to authenticate, provide with the authorization server to authenticate, provide consent, and
consent, and authorize the request as a resource owner. authorize the request as a resource owner.
The process by which the delegation happens is known as a grant, and The process by which the delegation happens is known as a grant, and
GNAP allows for the negotiation of the grant process over time by GNAP allows for the negotiation of the grant process over time by
multiple parties acting in distinct roles. multiple parties acting in distinct roles.
This specification focuses on the portions of the delegation process This specification focuses on the portions of the delegation process
facing the client instance. In particular, this specification facing the client instance. In particular, this specification
defines interoperable methods for a client instance to request, defines interoperable methods for a client instance to request,
negotiate, and receive access to information facilitated by the negotiate, and receive access to information facilitated by the
authorization server. This specification additionally defines authorization server. This specification additionally defines
methods for the client instance to access protected resources at a methods for the client instance to access protected resources at a
resource server. This specification also discusses discovery resource server. This specification also discusses discovery
mechanisms for the client instance to configure itself dynamically. mechanisms that enable the client instance to configure itself
The means for an authorization server and resource server to dynamically. The means for an authorization server and resource
interoperate are discussed in the companion document, server to interoperate are discussed in [GNAP-RS].
[I-D.ietf-gnap-resource-servers].
The focus of this protocol is to provide interoperability between the The focus of this protocol is to provide interoperability between the
different parties acting in each role, and is not to specify different parties acting in each role, not to specify implementation
implementation details of each. Where appropriate, GNAP may make details of each. Where appropriate, GNAP may make recommendations
recommendations about internal implementation details, but these about internal implementation details, but these recommendations are
recommendations are to ensure the security of the overall deployment to ensure the security of the overall deployment rather than to be
rather than to be prescriptive in the implementation. prescriptive in the implementation.
This protocol solves many of the same use cases as OAuth 2.0 This protocol solves many of the same use cases as OAuth 2.0
[RFC6749], OpenID Connect [OIDC], and the family of protocols that [RFC6749], OpenID Connect [OIDC], and the family of protocols that
have grown up around that ecosystem. However, GNAP is not an have grown up around that ecosystem. However, GNAP is not an
extension of OAuth 2.0 and is not intended to be directly compatible extension of OAuth 2.0 and is not intended to be directly compatible
with OAuth 2.0. GNAP seeks to provide functionality and solve use with OAuth 2.0. GNAP seeks to provide functionality and solve use
cases that OAuth 2.0 cannot easily or cleanly address. Appendix B cases that OAuth 2.0 cannot easily or cleanly address. Appendix A
further details the protocol rationale compared to OAuth 2.0. GNAP further details the protocol rationale compared to OAuth 2.0. GNAP
and OAuth 2.0 will likely exist in parallel for many deployments, and and OAuth 2.0 will likely exist in parallel for many deployments, and
considerations have been taken to facilitate the mapping and considerations have been taken to facilitate the mapping and
transition from existing OAuth 2.0 systems to GNAP. Some examples of transition from existing OAuth 2.0 systems to GNAP. Some examples of
these can be found in Appendix C.5. these can be found in Appendix B.5.
1.1. Terminology 1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This document contains non-normative examples of partial and complete This document contains non-normative examples of partial and complete
HTTP messages, JSON structures, URIs, query components, keys, and HTTP messages, JSON structures, URIs, query components, keys, and
other elements. Whenever possible, the document uses URI as a other elements. Whenever possible, the document uses URI as a
generic term, since it aligns with [RFC3986] recommendations and generic term, since it aligns with the recommendations in [RFC3986]
matches better with the intent that the identifier may be reachable and better matches the intent that the identifier may be reachable
through various/generic means (compared to URLs). Some examples use through various/generic means (compared to URLs). Some examples use
a single trailing backslash \ to indicate line wrapping for long a single trailing backslash (\) to indicate line wrapping for long
values, as per [RFC8792]. The \ character and leading spaces on values, as per [RFC8792]. The \ character and leading spaces on
wrapped lines are not part of the value. wrapped lines are not part of the value.
This document uses the term "mutual TLS" as defined by [RFC8705]. This document uses the term "mutual TLS" as defined by [RFC8705].
The shortened form "MTLS" is used to mean the same thing. The shortened form "MTLS" is used to mean the same thing.
For brevity, the term "signature" on its own is used in this document For brevity, the term "signature" on its own is used in this document
to refer to both digital signatures (which use asymmetric to refer to both digital signatures (which use asymmetric
cryptography) and keyed MACs (which use symmetric cryptography). cryptography) and keyed Message Authentication Codes (MACs) (which
Similarly, the verb "sign" refers to the generation of either a use symmetric cryptography). Similarly, the verb "sign" refers to
digital signature or keyed MAC over a given signature base. The the generation of either a digital signature or a keyed MAC over a
qualified term "digital signature" refers specifically to the output given signature base. The qualified term "digital signature" refers
of an asymmetric cryptographic signing operation. specifically to the output of an asymmetric cryptographic signing
operation.
1.2. Roles 1.2. Roles
The parties in GNAP perform actions under different roles. Roles are The parties in GNAP perform actions under different roles. Roles are
defined by the actions taken and the expectations leveraged on the defined by the actions taken and the expectations leveraged on the
role by the overall protocol. role by the overall protocol.
+-------------+ +------------+ +-------------+ +------------+
| | | | | | | |
|Authorization| | Resource | |Authorization| | Resource |
skipping to change at page 8, line 30 skipping to change at line 355
║ | Instance | ║ | Instance |
║ +----+-----+ ║ +----+-----+
║ ║ ║ ║
.----+----. ║ .----------. .----+----. ║ .----------.
| | +=====+ | | | +=====+ |
| Resource | | End | | Resource | | End |
| Owner | ~ ~ ~ ~ ~ ~ | User | | Owner | ~ ~ ~ ~ ~ ~ | User |
| | | | | | | |
`---------` `----------` `---------` `----------`
Legend Legend:
===== indicates interaction between a human and computer ===== indicates interaction between a human and computer
----- indicates interaction between two pieces of software ----- indicates interaction between two pieces of software
~ ~ ~ indicates a potential equivalence or out-of-band ~ ~ ~ indicates a potential equivalence or out-of-band
communication between roles communication between roles
Figure 1: Figure 1: Roles in GNAP Figure 1: Roles in GNAP
Authorization Server (AS): server that grants delegated privileges Authorization Server (AS): Server that grants delegated privileges
to a particular instance of client software in the form of access to a particular instance of client software in the form of access
tokens or other information (such as subject information). The AS tokens or other information (such as subject information). The AS
is uniquely defined by the _grant endpoint URI_, which is the is uniquely defined by the grant endpoint URI, which is the
absolute URI where grant requests are started by clients. absolute URI where grant requests are started by clients.
Client: application that consumes resources from one or several RSs, Client: Application that consumes resources from one or several
possibly requiring access privileges from one or several ASs. The resource servers, possibly requiring access privileges from one or
client is operated by the end user or it runs autonomously on several ASes. The client is operated by the end user, or it runs
behalf of a resource owner. autonomously on behalf of a resource owner.
Example: a client can be a mobile application, a web application, For example, a client can be a mobile application, a web
a back-end data processor, etc. application, a backend data processor, etc.
Note: this specification differentiates between a specific Note: This specification differentiates between a specific
instance (the client instance, identified by its unique key) and instance (the client instance, identified by its unique key) and
the software running the instance (the client software). For some the software running the instance (the client software). For some
kinds of client software, there could be many instances of that kinds of client software, there could be many instances of that
software, each instance with a different key. software, each instance with a different key.
Resource Server (RS): server that provides an API on protected Resource Server (RS): Server that provides an API on protected
resources, where operations on the API require a valid access resources, where operations on the API require a valid access
token issued by a trusted AS. token issued by a trusted AS.
Resource Owner (RO): subject entity that may grant or deny Resource Owner (RO): Subject entity that may grant or deny
operations on resources it has authority upon. operations on resources it has authority upon.
Note: the act of granting or denying an operation may be manual Note: The act of granting or denying an operation may be manual
(i.e. through an interaction with a physical person) or automatic (i.e., through an interaction with a physical person) or automatic
(i.e. through predefined organizational rules). (i.e., through predefined organizational rules).
End user: natural person that operates a client instance. End user: Natural person that operates a client instance.
Note: that natural person may or may not be the same entity as the Note: That natural person may or may not be the same entity as the
RO. RO.
The design of GNAP does not assume any one deployment architecture, The design of GNAP does not assume any one deployment architecture
but instead attempts to define roles that can be fulfilled in a but instead attempts to define roles that can be fulfilled in a
number of different ways for different use cases. As long as a given number of different ways for different use cases. As long as a given
role fulfills all of its obligations and behaviors as defined by the role fulfills all of its obligations and behaviors as defined by the
protocol, GNAP does not make additional requirements on its structure protocol, GNAP does not make additional requirements on its structure
or setup. or setup.
Multiple roles can be fulfilled by the same party, and a given party Multiple roles can be fulfilled by the same party, and a given party
can switch roles in different instances of the protocol. For can switch roles in different instances of the protocol. For
example, the RO and end user in many instances are the same person, example, in many instances, the RO and end user are the same person,
where a user is authorizing the client instance to act on their own where a user authorizes the client instance to act on their own
behalf at the RS. In this case, one party fulfills both of the RO behalf at the RS. In this case, one party fulfills the roles of both
and end-user roles, but the roles themselves are still defined RO and end user, but the roles themselves are still defined
separately from each other to allow for other use cases where they separately from each other to allow for other use cases where they
are fulfilled by different parties. are fulfilled by different parties.
For another example, in some complex scenarios, an RS receiving As another example, in some complex scenarios, an RS receiving
requests from one client instance can act as a client instance for a requests from one client instance can act as a client instance for a
downstream secondary RS in order to fulfill the original request. In downstream secondary RS in order to fulfill the original request. In
this case, one piece of software is both an RS and a client instance this case, one piece of software is both an RS and a client instance
from different perspectives, and it fulfills these roles separately from different perspectives, and it fulfills these roles separately
as far as the overall protocol is concerned. as far as the overall protocol is concerned.
A single role need not be deployed as a monolithic service. For A single role need not be deployed as a monolithic service. For
example, a client instance could have front-end components that are example, a client instance could have frontend components that are
installed on the end user's device as well as a back-end system that installed on the end user's device as well as a backend system that
the front-end communicates with. If both of these components the frontend communicates with. If both of these components
participate in the delegation protocol, they are both considered part participate in the delegation protocol, they are both considered part
of the client instance. If there are several copies of the client of the client instance. If there are several copies of the client
software that run separately but all share the same key material, software that run separately but all share the same key material,
such as a deployed cluster, then this cluster is considered a single such as a deployed cluster, then this cluster is considered a single
client instance. In these cases, the distinct components of what is client instance. In these cases, the distinct components of what is
considered a GNAP client instance may use any number of different considered a GNAP client instance may use any number of different
communication mechanisms between them, all of which would be communication mechanisms between them, all of which would be
considered an implementation detail of the client instances and out considered an implementation detail of the client instances and out
of scope of GNAP. of scope of GNAP.
For another example, an AS could likewise be built out of many As another example, an AS could likewise be built out of many
constituent components in a distributed architecture. The component constituent components in a distributed architecture. The component
that the client instance calls directly could be different from the that the client instance calls directly could be different from the
component that the RO interacts with to drive consent, since API component that the RO interacts with to drive consent, since API
calls and user interaction have different security considerations in calls and user interaction have different security considerations in
many environments. Furthermore, the AS could need to collect many environments. Furthermore, the AS could need to collect
identity claims about the RO from one system that deals with user identity claims about the RO from one system that deals with user
attributes while generating access tokens at another system that attributes while generating access tokens at another system that
deals with security rights. From the perspective of GNAP, all of deals with security rights. From the perspective of GNAP, all of
these are pieces of the AS and together fulfill the role of the AS as these are pieces of the AS and together fulfill the role of the AS as
defined by the protocol. These pieces may have their own internal defined by the protocol. These pieces may have their own internal
communications mechanisms which are considered out of scope of GNAP. communications mechanisms, which are considered out of scope of GNAP.
1.3. Elements 1.3. Elements
In addition to the roles above, the protocol also involves several In addition to the roles above, the protocol also involves several
elements that are acted upon by the roles throughout the process. elements that are acted upon by the roles throughout the process.
Access Token: a data artifact representing a set of rights and/or Access Token: A data artifact representing a set of rights and/or
attributes. attributes.
Note: an access token can be first issued to a client instance Note: An access token can be first issued to a client instance
(requiring authorization by the RO) and subsequently rotated. (requiring authorization by the RO) and subsequently rotated.
Grant: (verb): to permit an instance of client software to receive Grant: (verb): To permit an instance of client software to receive
some attributes at a specific time and valid for a specific some attributes at a specific time and with a specific duration of
duration and/or to exercise some set of delegated rights to access validity and/or to exercise some set of delegated rights to access
a protected resource; a protected resource.
(noun): the act of granting permission to a client instance. (noun): The act of granting permission to a client instance.
Privilege: right or attribute associated with a subject. Privilege: Right or attribute associated with a subject.
Note: the RO defines and maintains the rights and attributes Note: The RO defines and maintains the rights and attributes
associated to the protected resource, and might temporarily associated to the protected resource and might temporarily
delegate some set of those privileges to an end user. This delegate some set of those privileges to an end user. This
process is refered to as privilege delegation. process is referred to as "privilege delegation".
Protected Resource: protected API (Application Programming Protected Resource: Protected API that is served by an RS and that
Interface) served by an RS and that can be accessed by a client, can be accessed by a client, if and only if a valid and sufficient
if and only if a valid and sufficient access token is provided. access token is provided.
Note: to avoid complex sentences, the specification document may Note: To avoid complex sentences, the specification document may
simply refer to "resource" instead of "protected resource". simply refer to "resource" instead of "protected resource".
Right: ability given to a subject to perform a given operation on a Right: Ability given to a subject to perform a given operation on a
resource under the control of an RS. resource under the control of an RS.
Subject: person or organization. The subject decides whether and Subject: Person or organization. The subject decides whether and
under which conditions its attributes can be disclosed to other under which conditions its attributes can be disclosed to other
parties. parties.
Subject Information: set of statements and attributes asserted by an Subject Information: Set of statements and attributes asserted by an
AS about a subject. These statements can be used by the client AS about a subject. These statements can be used by the client
instance as part of an authentication decision. instance as part of an authentication decision.
1.4. Trust relationships 1.4. Trust Relationships
GNAP defines its trust objective as: "the RO trusts the AS to ensure GNAP defines its trust objective as follows: the RO trusts the AS to
access validation and delegation of protected resources to end users, ensure access validation and delegation of protected resources to end
through third party clients." users, through third party clients.
This trust objective can be decomposed into trust relationships This trust objective can be decomposed into trust relationships
between software elements and roles, especially the pairs end user/ between software elements and roles, especially the pairs end user/
RO, end user/client, client/AS, RS/RO, AS/RO, AS/RS. Trust of an RO, end user/client, client/AS, RS/RO, AS/RO, and AS/RS. Trust of an
agent by its pair can exist if the pair is informed that the agent agent by its pair can exist if the pair is informed that the agent
has made a promise to follow the protocol in the past (e.g. pre- has made a promise to follow the protocol in the past (e.g., pre-
registration, uncompromised cryptographic components) or if the pair registration and uncompromised cryptographic components) or if the
is able to infer by indirect means that the agent has made such a pair is able to infer by indirect means that the agent has made such
promise (e.g. a compliant client request). Each agent defines its a promise (e.g., a compliant client request). Each agent defines its
own valuation function of promises given or received. Examples of own valuation function of promises given or received. Examples of
such valuations can be the benefits from interacting with other such valuations can be the benefits from interacting with other
agents (e.g. safety in client access, interoperability with identity agents (e.g., safety in client access and interoperability with
standards), the cost of following the protocol (including its identity standards), the cost of following the protocol (including
security and privacy requirements and recommendations), a ranking of its security and privacy requirements and recommendations), a ranking
promise importance (e.g. a policy decision made by the AS), the of promise importance (e.g., a policy decision made by the AS), the
assessment of one's vulnerability or risk of not being able to defend assessment of one's vulnerability or risk of not being able to defend
against threats, etc. Those valuations may depend on the context of against threats, etc. Those valuations may depend on the context of
the request. For instance, the AS may decide to either take into the request. For instance, depending on the specific case in which
account or discard hints provided by the client, the RS may refuse GNAP is used, the AS may decide to either take into account or
bearer tokens, etc. depending on the specific case in which GNAP is discard hints provided by the client, or the RS may refuse bearer
used. Some promises can be affected by previous interactions (e.g., tokens. Some promises can be affected by previous interactions
repeated requests). (e.g., repeated requests).
Looking back on each trust relationship: Below are details of each trust relationship:
* end user/RO: this relationship exists only when the end user and end user/RO: This relationship exists only when the end user and the
the RO are different, in which case the end user needs some out of RO are different, in which case the end user needs some out-of-
band mechanism of getting the RO consent (see Section 4). GNAP band mechanism of getting the RO consent (see Section 4). GNAP
generally assumes that humans can be authenticated thanks to generally assumes that humans can be authenticated, thanks to
identity protocols (for instance, through an id_token assertion in identity protocols (for instance, through an id_token assertion as
Section 2.2). described in Section 2.2).
* end user/client: the client acts as a user agent. Depending on end user/client: The client acts as a user agent. Depending on the
the technology used (browser, SPA, mobile application, IoT device, technology used (browser, single-page application (SPA), mobile
etc.), some interactions may or may not be possible (as described application, Internet of Things (IoT) device, etc.), some
in Section 2.5.1). Client developers implement requirements and interactions may or may not be possible (as described in
Section 2.5.1). Client developers implement requirements and
generally some recommendations or best practices, so that the end generally some recommendations or best practices, so that the end
users may confidently use their software. However, end users users may confidently use their software. However, end users
might also be facing an attacker's client software or a poorly- might also face an attacker's client software or a poorly
implemented client, without even realizing it. implemented client without even realizing it.
* end user/AS: when the client supports the interaction feature (see end user/AS: When the client supports the interaction feature (see
Section 3.3), the end user interacts with the AS through an AS- Section 3.3), the end user interacts with the AS through an AS-
provided interface. In many cases, this happens through a front- provided interface. In many cases, this happens through a front-
channel interaction through the end user's browser. See channel interaction through the end user's browser. See
Section 13.29 for some considerations in trusting these Section 11.29 for some considerations in trusting these
interactions. interactions.
* client/AS: An honest AS may be facing an attacker's client (as client/AS: An honest AS may face an attacker's client (as discussed
discussed just above), or the reverse, and GNAP aims at making just above), or the reverse, and GNAP aims to make common attacks
common attacks impractical. The core specification makes access impractical. This specification makes access tokens opaque to the
tokens opaque to the client and defines the request/response client and defines the request/response scheme in detail,
scheme in detail, therefore avoiding extra trust hypotheses from therefore avoiding extra trust hypotheses from this critical piece
this critical piece of software. Yet the AS may further define of software. Yet, the AS may further define cryptographic
cryptographic attestations or optional rules to simplify the attestations or optional rules to simplify the access of clients
access of clients it already trusts, due to past behavior or it already trusts, due to past behavior or organizational policies
organizational policies (see Section 2.3). (see Section 2.3).
* RS/RO: the RS promises it protects its resources on behalf of the RS/RO: On behalf of the RO, the RS promises to protect its resources
RO from unauthorized access, and only accepts valid access tokens from unauthorized access and only accepts valid access tokens
issued by a trusted AS. In case tokens are key bound, proper issued by a trusted AS. In case tokens are key bound, proper
validation of the proof method is expected from the RS. validation of the proofing method is expected from the RS.
* AS/RO: the AS is expected to follow the decisions made by the RO, AS/RO: The AS is expected to follow the decisions made by the RO,
either through interactive consent requests, repeated through either interactive consent requests, repeated
interactions, or automated rules (as described in Section 1.6). interactions, or automated rules (as described in Section 1.6).
Privacy considerations aim to reduce the risk of an honest but Privacy considerations aim to reduce the risk of an honest but
too-curious AS, or the consequences of an unexpected user data too-curious AS or the consequences of an unexpected user data
exposure. exposure.
* AS/RS: the AS promises to issue valid access tokens to legitimate AS/RS: The AS promises to issue valid access tokens to legitimate
client requests (i.e. after carrying out appropriate due client requests (i.e., after carrying out appropriate due
diligence, as defined in the GNAP protocol). Some optional diligence, as defined in the GNAP). Some optional configurations
configurations are covered by [I-D.ietf-gnap-resource-servers]. are covered by [GNAP-RS].
A global assumption made by GNAP is that authorization requests are A global assumption made by GNAP is that authorization requests are
security and privacy sensitive, and appropriate measures are security and privacy sensitive, and appropriate measures are detailed
respectively detailed in Section 13 and Section 14. in Sections 11 and 12, respectively.
A formal trust model is out of scope of this specification, but one A formal trust model is out of scope of this specification, but one
could be developed using techniques such as [promise-theory]. could be developed using techniques such as the Promise Theory
[promise-theory].
1.5. Protocol Flow 1.5. Protocol Flow
GNAP is fundamentally designed to allow delegated access to APIs and GNAP is fundamentally designed to allow delegated access to APIs and
other information, such as subject information, using a multi-stage, other information, such as subject information, using a multi-stage,
stateful process. This process allows different parties to provide stateful process. This process allows different parties to provide
information into the system to alter and augment the state of the information into the system to alter and augment the state of the
delegated access and its artifacts. delegated access and its artifacts.
The underlying requested grant moves through several states as The underlying requested grant moves through several states as
different actions take place during the protocol: different actions take place during the protocol, as shown in
Figure 2.
.-----. .-----.
| | | |
+------+--+ | Continue +------+--+ | Continue
.---Need Interaction---->| | | .---Need Interaction---->| | |
/ | Pending |<--` / | Pending |<--`
/ .--Finish Interaction--+ | / .--Finish Interaction--+ |
/ / (approve/deny) +----+----+ / / (approve/deny) +----+----+
/ / | / / |
/ / | Cancel / / | Cancel
skipping to change at page 14, line 5 skipping to change at line 619
\ \ | Revoke or \ \ | Revoke or
\ \ | Finalize \ \ | Finalize
\ \ +-----+----+ \ \ +-----+----+
\ `-----Update---------+ | \ `-----Update---------+ |
\ | Approved |<--. \ | Approved |<--.
`-----No Interaction--->| | | `-----No Interaction--->| | |
+-------+--+ | Continue +-------+--+ | Continue
| | | |
`-----` `-----`
Figure 2: Figure 2: State diagram of a grant request throughout GNAP Figure 2: State Diagram of a Grant Request in GNAP
The state of the grant request is defined and managed by the AS, The state of the grant request is defined and managed by the AS,
though the client instance also needs to manage its view of the grant though the client instance also needs to manage its view of the grant
request over time. The means by which these roles manage their state request over time. The means by which these roles manage their state
is outside the scope of this specification. are outside the scope of this specification.
_Processing_: When a request for access (Section 2) is received by _Processing_: When a request for access (Section 2) is received by
the AS, a new grant request is created and placed in the the AS, a new grant request is created and placed in the
_processing_ state by the AS. This state is also entered when an _processing_ state by the AS. This state is also entered when an
existing grant request is updated by the client instance and when existing grant request is updated by the client instance and when
interaction is completed. In this state, the AS processes the interaction is completed. In this state, the AS processes the
context of the grant request to determine whether interaction with context of the grant request to determine whether interaction with
the end user or RO is required for approval of the request. The the end user or RO is required for approval of the request. The
grant request has to exit this state before a response can be grant request has to exit this state before a response can be
returned to the client instance. If approval is required, the returned to the client instance. If approval is required, the
request moves to the _pending_ state and the AS returns a continue request moves to the _pending_ state, and the AS returns a
response (Section 3.1) along with any appropriate interaction continuation response (Section 3.1) along with any appropriate
responses (Section 3.3). If no such approval is required, such as interaction responses (Section 3.3). If no such approval is
when the client instance is acting on its own behalf or the AS can required, such as when the client instance is acting on its own
determine that access has been fulfilled, the request moves to the behalf or the AS can determine that access has been fulfilled, the
_approved_ state where access tokens for API access (Section 3.2) request moves to the _approved_ state where access tokens for API
and subject information (Section 3.4) can be issued to the client access (Section 3.2) and subject information (Section 3.4) can be
instance. If the AS determines that no additional processing can issued to the client instance. If the AS determines that no
occur (such as a timeout or an unrecoverable error), the grant additional processing can occur (such as a timeout or an
request is moved to the _finalized_ state and is terminated. unrecoverable error), the grant request is moved to the
_finalized_ state and is terminated.
_Pending_: When a request needs to be approved by a RO, or _Pending_: When a request needs to be approved by an RO, or
interaction with the end user is required, the grant request interaction with the end user is required, the grant request
enters a state of _pending_. In this state, no access tokens can enters a state of _pending_. In this state, no access tokens can
be granted and no subject information can be released to the be granted, and no subject information can be released to the
client instance. While a grant request is in this state, the AS client instance. While a grant request is in this state, the AS
seeks to gather the required consent and authorization (Section 4) seeks to gather the required consent and authorization (Section 4)
for the requested access. A grant request in this state is always for the requested access. A grant request in this state is always
associated with a _continuation access token_ bound to the client associated with a continuation access token bound to the client
instance's key (see Section 3.1 for details of the continuation instance's key (see Section 3.1 for details of the continuation
access token). If no interaction finish method (Section 2.5.2) is access token). If no interaction finish method (Section 2.5.2) is
associated with this request, the client instance can send a associated with this request, the client instance can send a
polling continue request (Section 5.2) to the AS. This returns a polling continuation request (Section 5.2) to the AS. This
continue response (Section 3.1) while the grant request remains in returns a continuation response (Section 3.1) while the grant
this state, allowing the client instance to continue to check the request remains in this state, allowing the client instance to
state of the pending grant request. If an interaction finish continue to check the state of the pending grant request. If an
method (Section 2.5.2) is specified in the grant request, the interaction finish method (Section 2.5.2) is specified in the
client instance can continue the request after interaction grant request, the client instance can continue the request after
(Section 5.1) to the AS to move this request to the _processing_ interaction (Section 5.1) to the AS to move this request to the
state to be re-evaluated by the AS. Note that this occurs whether _processing_ state to be re-evaluated by the AS. Note that this
the grant request has been approved or denied by the RO, since the occurs whether the grant request has been approved or denied by
AS needs to take into account the full context of the request the RO, since the AS needs to take into account the full context
before determining the next step for the grant request. When of the request before determining the next step for the grant
other information is made available in the context of the grant request. When other information is made available in the context
request, such as through the asynchronous actions of the RO, the of the grant request, such as through the asynchronous actions of
AS moves this request to the _processing_ state to be re- the RO, the AS moves this request to the _processing_ state to be
evaluated. If the AS determines that no additional interaction re-evaluated. If the AS determines that no additional interaction
can occur, such as all the interaction methods have timed out or a can occur, e.g., all the interaction methods have timed out or a
revocation request (Section 5.4) is received from the client revocation request (Section 5.4) is received from the client
instance, the grant request can be moved to the _finalized_ state. instance, the grant request can be moved to the _finalized_ state.
_Approved_: When a request has been approved by an RO and no further _Approved_: When a request has been approved by an RO and no further
interaction with the end user is required, the grant request interaction with the end user is required, the grant request
enters a state of _approved_. In this state, responses to the enters a state of _approved_. In this state, responses to the
client instance can include access tokens for API access client instance can include access tokens for API access
(Section 3.2) and subject information (Section 3.4). If (Section 3.2) and subject information (Section 3.4). If
continuation and updates are allowed for this grant request, the continuation and updates are allowed for this grant request, the
AS can include the continuation response (Section 3.1). In this AS can include the continuation response (Section 3.1). In this
state, post-interaction continuation requests (Section 5.1) are state, post-interaction continuation requests (Section 5.1) are
not allowed and will result in an error, since all interaction is not allowed and will result in an error, since all interaction is
assumed to have been completed. If the client instance sends a assumed to have been completed. If the client instance sends a
polling continue request (Section 5.2) while the request is in polling continuation request (Section 5.2) while the request is in
this state, new access tokens (Section 3.2) can be issued in the this state, new access tokens (Section 3.2) can be issued in the
response. Note that this always creates a new access token, but response. Note that this always creates a new access token, but
any existing access tokens could be rotated and revoked using the any existing access tokens could be rotated and revoked using the
token management API (Section 6). The client instance can send an token management API (Section 6). The client instance can send an
update continuation request (Section 5.3) to modify the requested update continuation request (Section 5.3) to modify the requested
access, causing the AS to move the request back to the access, causing the AS to move the request back to the
_processing_ state for re-evaluation. If the AS determines that _processing_ state for re-evaluation. If the AS determines that
no additional tokens can be issued, and that no additional updates no additional tokens can be issued and that no additional updates
are to be accepted (such as the continuation access tokens have are to be accepted (e.g., the continuation access tokens have
expired), the grant is moved to the _finalized_ state. expired), the grant is moved to the _finalized_ state.
_Finalized_: After the access tokens are issued, if the AS does not _Finalized_: After the access tokens are issued, if the AS does not
allow any additional updates on the grant request, the grant allow any additional updates on the grant request, the grant
request enters the _finalized_ state. This state is also entered request enters the _finalized_ state. This state is also entered
when an existing grant request is revoked by the client instance when an existing grant request is revoked by the client instance
(Section 5.4) or otherwise revoked by the AS (such as through out- (Section 5.4) or otherwise revoked by the AS (such as through out-
of-band action by the RO). This state can also be entered if the of-band action by the RO). This state can also be entered if the
AS determines that no additional processing is possible, for AS determines that no additional processing is possible, for
example if the RO has denied the requested access or if example, if the RO has denied the requested access or if
interaction is required but no compatible interaction methods are interaction is required but no compatible interaction methods are
available. Once in this state, no new access tokens can be available. Once in this state, no new access tokens can be
issued, no subject information can be returned, and no issued, no subject information can be returned, and no
interactions can take place. Once in this state, the grant interactions can take place. Once in this state, the grant
request is dead and cannot be revived. If future access is request is dead and cannot be revived. If future access is
desired by the client instance, a new grant request can be desired by the client instance, a new grant request can be
created, unrelated to this grant request. created, unrelated to this grant request.
While it is possible to deploy an AS in a stateless environment, GNAP While it is possible to deploy an AS in a stateless environment, GNAP
is a stateful protocol and such deployments will need a way to manage is a stateful protocol, and such deployments will need a way to
the current state of the grant request in a secure and deterministic manage the current state of the grant request in a secure and
fashion without relying on other components, such as the client deterministic fashion without relying on other components, such as
software, to keep track of the current state. the client software, to keep track of the current state.
1.6. Sequences 1.6. Sequences
GNAP can be used in a variety of ways to allow the core delegation GNAP can be used in a variety of ways to allow the core delegation
process to take place. Many portions of this process are process to take place. Many portions of this process are
conditionally present depending on the context of the deployments, conditionally present depending on the context of the deployments,
and not every step in this overview will happen in all circumstances. and not every step in this overview will happen in all circumstances.
Note that a connection between roles in this process does not Note that a connection between roles in this process does not
necessarily indicate that a specific protocol message is sent across necessarily indicate that a specific protocol message is sent across
the wire between the components fulfilling the roles in question, or the wire between the components fulfilling the roles in question or
that a particular step is required every time. For example, for a that a particular step is required every time. For example, for a
client instance interested in only getting subject information client instance interested in only getting subject information
directly, and not calling an RS, all steps involving the RS below do directly and not calling an RS, all steps involving the RS below do
not apply. not apply.
In some circumstances, the information needed at a given stage is In some circumstances, the information needed at a given stage is
communicated out of band or is preconfigured between the components communicated out of band or is pre-configured between the components
or entities performing the roles. For example, one entity can or entities performing the roles. For example, one entity can
fulfill multiple roles, and so explicit communication between the fulfill multiple roles, so explicit communication between the roles
roles is not necessary within the protocol flow. Additionally some is not necessary within the protocol flow. Additionally, some
components may not be involved in all use cases. For example, a components may not be involved in all use cases. For example, a
client instance could be calling the AS just to get direct user client instance could be calling the AS just to get direct user
information and have no need to get an access token to call an RS. information and have no need to get an access token to call an RS.
1.6.1. Overall Protocol Sequence 1.6.1. Overall Protocol Sequence
The following diagram provides a general overview of GNAP, including The following diagram provides a general overview of GNAP, including
many different optional phases and connections. The diagrams in the many different optional phases and connections. The diagrams in the
following sections provide views of GNAP under more specific following sections provide views of GNAP under more specific
circumstances. These additional diagrams use the same conventions as circumstances. These additional diagrams use the same conventions as
skipping to change at page 17, line 37 skipping to change at line 785
| | | | | | | | | | | |
| +--(9)-->| | | | | +--(9)-->| | | |
| |<-(10)--+ | | | | |<-(10)--+ | | |
| | | | | | | | | | | |
| +---------------(11)------------>| | | +---------------(11)------------>| |
| | | | (12) | | | | | | (12) | |
| +--(13)->| | | | | +--(13)->| | | |
| | | | | | | | | | | |
+--------+ +---------------+ +------------+ +--------+ +---------------+ +------------+
Legend Legend:
===== indicates a possible interaction with a human ===== indicates a possible interaction with a human
----- indicates an interaction between protocol roles ----- indicates an interaction between protocol roles
~ ~ ~ indicates a potential equivalence or out-of-band ~ ~ ~ indicates a potential equivalence or out-of-band
communication between roles communication between roles
Figure 3: Figure 3: Overall sequence of GNAP Figure 3: Overall Sequence of GNAP
* (A) The end user interacts with the client instance to indicate a * (A) The end user interacts with the client instance to indicate a
need for resources on behalf of the RO. This could identify the need for resources on behalf of the RO. This could identify the
RS the client instance needs to call, the resources needed, or the RS that the client instance needs to call, the resources needed,
RO that is needed to approve the request. Note that the RO and or the RO that is needed to approve the request. Note that the RO
end user are often the same entity in practice, but GNAP makes no and end user are often the same entity in practice, but GNAP makes
general assumption that they are. no general assumption that they are.
* (1) The client instance determines what access is needed and which * (1) The client instance determines what access is needed and which
AS to approach for access. Note that for most situations, the AS to approach for access. Note that for most situations, the
client instance is pre-configured with which AS to talk to and client instance is pre-configured with which AS to talk to and
which kinds of access it needs, but some more dynamic processes which kinds of access it needs, but some more dynamic processes
are discussed in Section 9.1. are discussed in Section 9.1.
* (2) The client instance requests access at the AS (Section 2). * (2) The client instance requests access at the AS (Section 2).
* (3) The AS processes the request and determines what is needed to * (3) The AS processes the request and determines what is needed to
fulfill the request (See Section 4). The AS sends its response to fulfill the request (see Section 4). The AS sends its response to
the client instance (Section 3). the client instance (Section 3).
* (B) If interaction is required, the AS interacts with the RO * (B) If interaction is required, the AS interacts with the RO
(Section 4) to gather authorization. The interactive component of (Section 4) to gather authorization. The interactive component of
the AS can function using a variety of possible mechanisms the AS can function using a variety of possible mechanisms,
including web page redirects, applications, challenge/response including web page redirects, applications, challenge/response
protocols, or other methods. The RO approves the request for the protocols, or other methods. The RO approves the request for the
client instance being operated by the end user. Note that the RO client instance being operated by the end user. Note that the RO
and end user are often the same entity in practice, and many of and end user are often the same entity in practice, and many of
GNAP's interaction methods allow the client instance to facilitate GNAP's interaction methods allow the client instance to facilitate
the end user interacting with the AS in order to fulfill the role the end user interacting with the AS in order to fulfill the role
of the RO. of the RO.
* (4) The client instance continues the grant at the AS (Section 5). * (4) The client instance continues the grant at the AS (Section 5).
This action could occur in response to receiving a signal that This action could occur in response to receiving a signal that
interaction has finished (Section 4.2) or through a periodic interaction has finished (Section 4.2) or through a periodic
polling mechanism, depending on the interaction capabilities of polling mechanism, depending on the interaction capabilities of
the client software and the options active in the grant request. the client software and the options active in the grant request.
* (5) If the AS determines that access can be granted, it returns a * (5) If the AS determines that access can be granted, it returns a
response to the client instance (Section 3) including an access response to the client instance (Section 3), including an access
token (Section 3.2) for calling the RS and any directly returned token (Section 3.2) for calling the RS and any directly returned
information (Section 3.4) about the RO. information (Section 3.4) about the RO.
* (6) The client instance uses the access token (Section 7.2) to * (6) The client instance uses the access token (Section 7.2) to
call the RS. call the RS.
* (7) The RS determines if the token is sufficient for the request * (7) The RS determines if the token is sufficient for the request
by examining the token. The means of the RS determining this by examining the token. The means of the RS determining this
access are out of scope of this specification, but some options access are out of scope of this specification, but some options
are discussed in [I-D.ietf-gnap-resource-servers]. are discussed in [GNAP-RS].
* (8) The client instance calls the RS (Section 7.2) using the * (8) The client instance calls the RS (Section 7.2) using the
access token until the RS or client instance determine that the access token until the RS or client instance determines that the
token is no longer valid. token is no longer valid.
* (9) When the token no longer works, the client instance rotates * (9) When the token no longer works, the client instance rotates
the access token (Section 6.1). the access token (Section 6.1).
* (10) The AS issues a new access token (Section 3.2) to the client * (10) The AS issues a new access token (Section 3.2) to the client
instance with the same rights as the original access token instance with the same rights as the original access token
returned in (5). returned in (5).
* (11) The client instance uses the new access token (Section 7.2) * (11) The client instance uses the new access token (Section 7.2)
to call the RS. to call the RS.
* (12) The RS determines if the new token is sufficient for the * (12) The RS determines if the new token is sufficient for the
request, as in (7). request, as in (7).
* (13) The client instance disposes of the token (Section 6.2) once * (13) The client instance disposes of the token (Section 6.2) once
the client instance has completed its access of the RS and no the client instance has completed its access of the RS and no
longer needs the token. longer needs the token.
The following sections and Appendix C contain specific guidance on The following sections and Appendix B contain specific guidance on
how to use GNAP in different situations and deployments. For how to use GNAP in different situations and deployments. For
example, it is possible for the client instance to never request an example, it is possible for the client instance to never request an
access token and never call an RS, just as it is possible to have no access token and never call an RS, just as it is possible to have no
end user involved in the delegation process. end user involved in the delegation process.
1.6.2. Redirect-based Interaction 1.6.2. Redirect-Based Interaction
In this example flow, the client instance is a web application that In this example flow, the client instance is a web application that
wants access to resources on behalf of the current user, who acts as wants access to resources on behalf of the current user, who acts as
both the end user and the resource owner (RO). Since the client both the end user and the RO. Since the client instance is capable
instance is capable of directing the user to an arbitrary URI and of directing the user to an arbitrary URI and receiving responses
receiving responses from the user's browser, interaction here is from the user's browser, interaction here is handled through front-
handled through front-channel redirects using the user's browser. channel redirects using the user's browser. The redirection URI used
The redirection URI used for interaction is a service hosted by the for interaction is a service hosted by the AS in this example. The
AS in this example. The client instance uses a persistent session client instance uses a persistent session with the user to ensure the
with the user to ensure the same user that is starting the same user that is starting the interaction is the user that returns
interaction is the user that returns from the interaction. from the interaction.
+--------+ +--------+ .----. +--------+ +--------+ .----.
| Client | | AS | | End | | Client | | AS | | End |
|Instance| | | | User | |Instance| | | | User |
| |<=(1)== Start Session ===============================+ | | |<=(1)== Start Session ===============================+ |
| | | | | | | | | | | |
| +--(2)--- Request Access --------->| | | | | +--(2)--- Request Access --------->| | | |
| | | | | | | | | | | |
| |<-(3)-- Interaction Needed -------+ | | | | |<-(3)-- Interaction Needed -------+ | | |
| | | | | | | | | | | |
skipping to change at page 20, line 35 skipping to change at line 912
| | | | | | | |
| |<-(9)----- Grant Access ----------+ | | |<-(9)----- Grant Access ----------+ |
| | | | | | | |
| | | | +--------+ | | | | +--------+
| +--(10)-- Access API ---------------------------->| RS | | +--(10)-- Access API ---------------------------->| RS |
| | | | | | | | | | | |
| |<-(11)-- API Response ---------------------------| | | |<-(11)-- API Response ---------------------------| |
| | | | +--------+ | | | | +--------+
+--------+ +--------+ +--------+ +--------+
Figure 4: Figure 4: Diagram of a redirect-based interaction Figure 4: Diagram of a Redirect-Based Interaction
1. The client instance establishes a session with the user, in the * (1) The client instance establishes a session with the user, in
role of the end user. the role of the end user.
2. The client instance requests access to the resource (Section 2). * (2) The client instance requests access to the resource
The client instance indicates that it can redirect to an (Section 2). The client instance indicates that it can redirect
arbitrary URI (Section 2.5.1.1) and receive a redirect from the to an arbitrary URI (Section 2.5.1.1) and receive a redirect from
browser (Section 2.5.2.1). The client instance stores the browser (Section 2.5.2.1). The client instance stores
verification information for its redirect in the session created verification information for its redirect in the session created
in (1). in (1).
3. The AS determines that interaction is needed and responds * (3) The AS determines that interaction is needed and responds
(Section 3) with a URI to send the user to (Section 3.3.1) and (Section 3) with a URI to send the user to (Section 3.3.1) and
information needed to verify the redirect (Section 3.3.5) in information needed to verify the redirect (Section 3.3.5) in (7).
(7). The AS also includes information the client instance will The AS also includes information the client instance will need to
need to continue the request (Section 3.1) in (8). The AS continue the request (Section 3.1) in (8). The AS associates this
associates this continuation information with an ongoing request continuation information with an ongoing request that will be
that will be referenced in (4), (6), and (8). referenced in (4), (6), and (8).
4. The client instance stores the verification and continuation * (4) The client instance stores the verification and continuation
information from (3) in the session from (1). The client information from (3) in the session from (1). The client instance
instance then redirects the user to the URI (Section 4.1.1) then redirects the user to the URI (Section 4.1.1) given by the AS
given by the AS in (3). The user's browser loads the in (3). The user's browser loads the interaction redirect URI.
interaction redirect URI. The AS loads the pending request The AS loads the pending request based on the incoming URI
based on the incoming URI generated in (3). generated in (3).
5. The user authenticates at the AS, taking on the role of the RO. * (5) The user authenticates at the AS, taking on the role of the
RO.
6. As the RO, the user authorizes the pending request from the * (6) As the RO, the user authorizes the pending request from the
client instance. client instance.
7. When the AS is done interacting with the user, the AS redirects * (7) When the AS is done interacting with the user, the AS
the user back (Section 4.2.1) to the client instance using the redirects the user back (Section 4.2.1) to the client instance
redirect URI provided in (2). The redirect URI is augmented using the redirect URI provided in (2). The redirect URI is
with an interaction reference that the AS associates with the augmented with an interaction reference that the AS associates
ongoing request created in (2) and referenced in (4). The with the ongoing request created in (2) and referenced in (4).
redirect URI is also augmented with a hash of the security The redirect URI is also augmented with a hash of the security
information provided in (2) and (3). The client instance loads information provided in (2) and (3). The client instance loads
the verification information from (2) and (3) from the session the verification information from (2) and (3) from the session
created in (1). The client instance calculates a hash created in (1). The client instance calculates a hash
(Section 4.2.3) based on this information and continues only if (Section 4.2.3) based on this information and continues only if
the hash validates. Note that the client instance needs to the hash validates. Note that the client instance needs to ensure
ensure that the parameters for the incoming request match those that the parameters for the incoming request match those that it
that it is expecting from the session created in (1). The is expecting from the session created in (1). The client instance
client instance also needs to be prepared for the end user never also needs to be prepared for the end user never being returned to
being returned to the client instance and handle timeouts the client instance and handle timeouts appropriately.
appropriately.
8. The client instance loads the continuation information from (3) * (8) The client instance loads the continuation information from
and sends the interaction reference from (7) in a request to (3) and sends the interaction reference from (7) in a request to
continue the request (Section 5.1). The AS validates the continue the request (Section 5.1). The AS validates the
interaction reference ensuring that the reference is associated interaction reference, ensuring that the reference is associated
with the request being continued. with the request being continued.
9. If the request has been authorized, the AS grants access to the * (9) If the request has been authorized, the AS grants access to
information in the form of access tokens (Section 3.2) and the information in the form of access tokens (Section 3.2) and
direct subject information (Section 3.4) to the client instance. direct subject information (Section 3.4) to the client instance.
10. The client instance uses the access token (Section 7.2) to call * (10) The client instance uses the access token (Section 7.2) to
the RS. call the RS.
11. The RS validates the access token and returns an appropriate * (11) The RS validates the access token and returns an appropriate
response for the API. response for the API.
An example set of protocol messages for this method can be found in An example set of protocol messages for this method can be found in
Appendix C.1. Appendix B.1.
1.6.3. User-code Interaction 1.6.3. User Code Interaction
In this example flow, the client instance is a device that is capable In this example flow, the client instance is a device that is capable
of presenting a short, human-readable code to the user and directing of presenting a short, human-readable code to the user and directing
the user to enter that code at a known URI. The user enters the code the user to enter that code at a known URI. The user enters the code
at a URI that is an interactive service hosted by the AS in this at a URI that is an interactive service hosted by the AS in this
example. The client instance is not capable of presenting an example. The client instance is not capable of presenting an
arbitrary URI to the user, nor is it capable of accepting incoming arbitrary URI to the user, nor is it capable of accepting incoming
HTTP requests from the user's browser. The client instance polls the HTTP requests from the user's browser. The client instance polls the
AS while it is waiting for the RO to authorize the request. The AS while it is waiting for the RO to authorize the request. The
user's interaction is assumed to occur on a secondary device. In user's interaction is assumed to occur on a secondary device. In
this example it is assumed that the user is both the end user and RO. this example, it is assumed that the user is both the end user and
Note that since the user is not assumed to be interacting with the RO. Note that since the user is not assumed to be interacting with
client instance through the same web browser used for interaction at the client instance through the same web browser used for interaction
the AS, the user is not shown as being connected to the client at the AS, the user is not shown as being connected to the client
instance in this diagram. instance in this diagram.
+--------+ +--------+ .----. +--------+ +--------+ .----.
| Client | | AS | | End | | Client | | AS | | End |
|Instance+--(1)--- Request Access --------->| | | User | |Instance+--(1)--- Request Access --------->| | | User |
| | | | | | | | | | | |
| |<-(2)-- Interaction Needed -------+ | | | | |<-(2)-- Interaction Needed -------+ | | |
| | | | | | | | | | | |
| +==(3)==== Display User Code ========================>| | | +==(3)==== Display User Code ========================>| |
| | | | | | | | | | | |
skipping to change at page 23, line 39 skipping to change at line 1031
| | | | | User | | | | | | User |
| |<-(12)----- Grant Access ---------+ | `----` | |<-(12)----- Grant Access ---------+ | `----`
| | | | | | | |
| | | | +--------+ | | | | +--------+
| +--(13)-- Access API ---------------------------->| RS | | +--(13)-- Access API ---------------------------->| RS |
| | | | | | | | | | | |
| |<-(14)-- API Response ---------------------------+ | | |<-(14)-- API Response ---------------------------+ |
| | | | +--------+ | | | | +--------+
+--------+ +--------+ +--------+ +--------+
Figure 5: Figure 5: Diagram of a user-code-based interaction Figure 5: Diagram of a User-Code-Based Interaction
1. The client instance requests access to the resource (Section 2). * (1) The client instance requests access to the resource
The client instance indicates that it can display a user code (Section 2). The client instance indicates that it can display a
(Section 2.5.1.3). user code (Section 2.5.1.3).
2. The AS determines that interaction is needed and responds * (2) The AS determines that interaction is needed and responds
(Section 3) with a user code to communicate to the user (Section 3) with a user code to communicate to the user
(Section 3.3.3). The AS also includes information the client (Section 3.3.3). The AS also includes information the client
instance will need to continue the request (Section 3.1) in (8) instance will need to continue the request (Section 3.1) in (8)
and (10). The AS associates this continuation information with and (10). The AS associates this continuation information with an
an ongoing request that will be referenced in (4), (6), (8), and ongoing request that will be referenced in (4), (6), (8), and
(10). (10).
3. The client instance stores the continuation information from (2) * (3) The client instance stores the continuation information from
for use in (8) and (10). The client instance then communicates (2) for use in (8) and (10). The client instance then
the code to the user (Section 4.1.2) given by the AS in (2). communicates the code to the user (Section 4.1.2) given by the AS
in (2).
4. The users directs their browser to the user code URI. This URI * (4) The user directs their browser to the user code URI. This URI
is stable and can be communicated via the client software's is stable and can be communicated via the client software's
documentation, the AS documentation, or the client software documentation, the AS documentation, or the client software
itself. Since it is assumed that the RO will interact with the itself. Since it is assumed that the RO will interact with the AS
AS through a secondary device, the client instance does not through a secondary device, the client instance does not provide a
provide a mechanism to launch the RO's browser at this URI. mechanism to launch the RO's browser at this URI.
5. The end user authenticates at the AS, taking on the role of the * (5) The end user authenticates at the AS, taking on the role of
RO. the RO.
6. The RO enters the code communicated in (3) to the AS. The AS * (6) The RO enters the code communicated in (3) to the AS. The AS
validates this code against a current request in process. validates this code against a current request in process.
7. As the RO, the user authorizes the pending request from the * (7) As the RO, the user authorizes the pending request from the
client instance. client instance.
8. When the AS is done interacting with the user, the AS indicates * (8) When the AS is done interacting with the user, the AS
to the RO that the request has been completed. indicates to the RO that the request has been completed.
9. Meanwhile, the client instance loads the continuation * (9) Meanwhile, the client instance loads the continuation
information stored at (3) and continues the request (Section 5). information stored at (3) and continues the request (Section 5).
The AS determines which ongoing access request is referenced The AS determines which ongoing access request is referenced here
here and checks its state. and checks its state.
10. If the access request has not yet been authorized by the RO in * (10) If the access request has not yet been authorized by the RO
(6), the AS responds to the client instance to continue the in (6), the AS responds to the client instance to continue the
request (Section 3.1) at a future time through additional polled request (Section 3.1) at a future time through additional polled
continuation requests. This response can include updated continuation requests. This response can include updated
continuation information as well as information regarding how continuation information as well as information regarding how long
long the client instance should wait before calling again. The the client instance should wait before calling again. The client
client instance replaces its stored continuation information instance replaces its stored continuation information from the
from the previous response (2). Note that the AS may need to previous response (2). Note that the AS may need to determine
determine that the RO has not approved the request in a that the RO has not approved the request in a sufficient amount of
sufficient amount of time and return an appropriate error to the time and return an appropriate error to the client instance.
client instance.
11. The client instance continues to poll the AS (Section 5.2) with * (11) The client instance continues to poll the AS (Section 5.2)
the new continuation information in (9). with the new continuation information in (9).
12. If the request has been authorized, the AS grants access to the * (12) If the request has been authorized, the AS grants access to
information in the form of access tokens (Section 3.2) and the information in the form of access tokens (Section 3.2) and
direct subject information (Section 3.4) to the client instance. direct subject information (Section 3.4) to the client instance.
13. The client instance uses the access token (Section 7.2) to call * (13) The client instance uses the access token (Section 7.2) to
the RS. call the RS.
14. The RS validates the access token and returns an appropriate * (14) The RS validates the access token and returns an appropriate
response for the API. response for the API.
An example set of protocol messages for this method can be found in An example set of protocol messages for this method can be found in
Appendix C.2. Appendix B.2.
1.6.4. Asynchronous Authorization 1.6.4. Asynchronous Authorization
In this example flow, the end user and RO roles are fulfilled by In this example flow, the end user and RO roles are fulfilled by
different parties, and the RO does not interact with the client different parties, and the RO does not interact with the client
instance. The AS reaches out asynchronously to the RO during the instance. The AS reaches out asynchronously to the RO during the
request process to gather the RO's authorization for the client request process to gather the RO's authorization for the client
instance's request. The client instance polls the AS while it is instance's request. The client instance polls the AS while it is
waiting for the RO to authorize the request. waiting for the RO to authorize the request.
skipping to change at page 25, line 48 skipping to change at line 1135
| | | | | | | |
| |<-(9)------ Grant Access ---------+ | | |<-(9)------ Grant Access ---------+ |
| | | | | | | |
| | | | +--------+ | | | | +--------+
| +--(10)-- Access API ---------------------------->| RS | | +--(10)-- Access API ---------------------------->| RS |
| | | | | | | | | | | |
| |<-(11)-- API Response ---------------------------+ | | |<-(11)-- API Response ---------------------------+ |
| | | | +--------+ | | | | +--------+
+--------+ +--------+ +--------+ +--------+
Figure 6: Figure 6: Diagram of an asynchronous authorization Figure 6: Diagram of an Asynchronous Authorization Process, with
process, with no end user interaction No End-User Interaction
1. The client instance requests access to the resource (Section 2). * (1) The client instance requests access to the resource
The client instance does not send any interaction modes to the (Section 2). The client instance does not send any interaction
server, indicating that it does not expect to interact with the modes to the server, indicating that it does not expect to
RO. The client instance can also signal which RO it requires interact with the RO. The client instance can also signal which
authorization from, if known, by using the subject request RO it requires authorization from, if known, by using the subject
(Section 2.2) and user request (Section 2.4) sections. It's request field (Section 2.2) and user request field (Section 2.4).
also possible for the AS to determine which RO needs to be It's also possible for the AS to determine which RO needs to be
contacted by the nature of what access is being requested. contacted by the nature of what access is being requested.
2. The AS determines that interaction is needed, but the client * (2) The AS determines that interaction is needed, but the client
instance cannot interact with the RO. The AS responds instance cannot interact with the RO. The AS responds (Section 3)
(Section 3) with the information the client instance will need with the information the client instance will need to continue the
to continue the request (Section 3.1) in (6) and (8), including request (Section 3.1) in (6) and (8), including a signal that the
a signal that the client instance should wait before checking client instance should wait before checking the status of the
the status of the request again. The AS associates this request again. The AS associates this continuation information
continuation information with an ongoing request that will be with an ongoing request that will be referenced in (3), (4), (5),
referenced in (3), (4), (5), (6), and (8). (6), and (8).
3. The AS determines which RO to contact based on the request in * (3) The AS determines which RO to contact based on the request in
(1), through a combination of the user request (Section 2.4), (1), through a combination of the user request (Section 2.4), the
the subject request (Section 2.2), the access request subject request (Section 2.2), the access request (Section 2.1),
(Section 2.1), and other policy information. The AS contacts and other policy information. The AS contacts the RO and
the RO and authenticates them. authenticates them.
4. The RO authorizes the pending request from the client instance. * (4) The RO authorizes the pending request from the client
instance.
5. When the AS is done interacting with the RO, the AS indicates to * (5) When the AS is done interacting with the RO, the AS indicates
the RO that the request has been completed. to the RO that the request has been completed.
6. Meanwhile, the client instance loads the continuation * (6) Meanwhile, the client instance loads the continuation
information stored at (2) and continues the request (Section 5). information stored at (2) and continues the request (Section 5).
The AS determines which ongoing access request is referenced The AS determines which ongoing access request is referenced here
here and checks its state. and checks its state.
7. If the access request has not yet been authorized by the RO in * (7) If the access request has not yet been authorized by the RO in
(6), the AS responds to the client instance to continue the (6), the AS responds to the client instance to continue the
request (Section 3.1) at a future time through additional request (Section 3.1) at a future time through additional polling.
polling. Note that this response is not an error message, since Note that this response is not an error message, since no error
no error has yet occurred. This response can include refreshed has yet occurred. This response can include refreshed credentials
credentials as well as information regarding how long the client as well as information regarding how long the client instance
instance should wait before calling again. The client instance should wait before calling again. The client instance replaces
replaces its stored continuation information from the previous its stored continuation information from the previous response
response (2). Note that the AS may need to determine that the (2). Note that the AS may need to determine that the RO has not
RO has not approved the request in a sufficient amount of time approved the request in a sufficient amount of time and return an
and return an appropriate error to the client instance. appropriate error to the client instance.
8. The client instance continues to poll the AS (Section 5.2) with * (8) The client instance continues to poll the AS (Section 5.2)
the new continuation information from (7). with the new continuation information from (7).
9. If the request has been authorized, the AS grants access to the * (9) If the request has been authorized, the AS grants access to
information in the form of access tokens (Section 3.2) and the information in the form of access tokens (Section 3.2) and
direct subject information (Section 3.4) to the client instance. direct subject information (Section 3.4) to the client instance.
10. The client instance uses the access token (Section 7.2) to call * (10) The client instance uses the access token (Section 7.2) to
the RS. call the RS.
11. The RS validates the access token and returns an appropriate * (11) The RS validates the access token and returns an appropriate
response for the API. response for the API.
An example set of protocol messages for this method can be found in An example set of protocol messages for this method can be found in
Appendix C.4. Appendix B.4.
Additional considerations for asynchronous interactions like this are Additional considerations for asynchronous interactions like this are
discussed in Section 13.36. discussed in Section 11.36.
1.6.5. Software-only Authorization 1.6.5. Software-Only Authorization
In this example flow, the AS policy allows the client instance to In this example flow, the AS policy allows the client instance to
make a call on its own behalf, without the need for an RO to be make a call on its own behalf, without the need for an RO to be
involved at runtime to approve the decision. Since there is no involved at runtime to approve the decision. Since there is no
explicit RO, the client instance does not interact with an RO. explicit RO, the client instance does not interact with an RO.
+--------+ +--------+ +--------+ +--------+
| Client | | AS | | Client | | AS |
|Instance+--(1)--- Request Access --->| | |Instance+--(1)--- Request Access --->| |
| | | | | | | |
| |<-(2)---- Grant Access -----+ | | |<-(2)---- Grant Access -----+ |
| | | | +--------+ | | | | +--------+
| +--(3)--- Access API ------------------->| RS | | +--(3)--- Access API ------------------->| RS |
| | | | | | | | | | | |
| |<-(4)--- API Response ------------------+ | | |<-(4)--- API Response ------------------+ |
| | | | +--------+ | | | | +--------+
+--------+ +--------+ +--------+ +--------+
Figure 7: Figure 7: Diagram of a software-only authorization, Figure 7: Diagram of a Software-Only Authorization, with No End
with no end user or explicit resource owner User or Explicit Resource Owner
1. The client instance requests access to the resource (Section 2). * (1) The client instance requests access to the resource
The client instance does not send any interaction modes to the (Section 2). The client instance does not send any interaction
server. modes to the server.
2. The AS determines that the request has been authorized based on * (2) The AS determines that the request has been authorized based
the identity of the client instance making the request and the on the identity of the client instance making the request and the
access requested (Section 2.1). The AS grants access to the access requested (Section 2.1). The AS grants access to the
resource in the form of access tokens (Section 3.2) to the client resource in the form of access tokens (Section 3.2) to the client
instance. Note that direct subject information (Section 3.4) is instance. Note that direct subject information (Section 3.4) is
not generally applicable in this use case, as there is no user not generally applicable in this use case, as there is no user
involved. involved.
3. The client instance uses the access token (Section 7.2) to call * (3) The client instance uses the access token (Section 7.2) to
the RS. call the RS.
4. The RS validates the access token and returns an appropriate * (4) The RS validates the access token and returns an appropriate
response for the API. response for the API.
An example set of protocol messages for this method can be found in An example set of protocol messages for this method can be found in
Appendix C.3. Appendix B.3.
1.6.6. Refreshing an Expired Access Token 1.6.6. Refreshing an Expired Access Token
In this example flow, the client instance receives an access token to In this example flow, the client instance receives an access token to
access a resource server through some valid GNAP process. The client access an RS through some valid GNAP process. The client instance
instance uses that token at the RS for some time, but eventually the uses that token at the RS for some time, but eventually the access
access token expires. The client instance then gets a refreshed token expires. The client instance then gets a refreshed access
access token by rotating the expired access token's value at the AS token by rotating the expired access token's value at the AS using
using the token management API. the token management API.
+--------+ +--------+ +--------+ +--------+
| Client | | AS | | Client | | AS |
|Instance+--(1)--- Request Access ----------------->| | |Instance+--(1)--- Request Access ----------------->| |
| | | | | | | |
| |<-(2)--- Grant Access --------------------+ | | |<-(2)--- Grant Access --------------------+ |
| | | | | | | |
| | +--------+ | | | | +--------+ | |
| +--(3)--- Access Resource --->| RS | | | | +--(3)--- Access Resource --->| RS | | |
| | | | | | | | | | | |
skipping to change at page 29, line 29 skipping to change at line 1280
| | | | | | | | | | | |
| |<-(6)--- Error Response -----+ | | | | |<-(6)--- Error Response -----+ | | |
| | +--------+ | | | | +--------+ | |
| | | | | | | |
| +--(7)--- Rotate Token ------------------->| | | +--(7)--- Rotate Token ------------------->| |
| | | | | | | |
| |<-(8)--- Rotated Token -------------------+ | | |<-(8)--- Rotated Token -------------------+ |
| | | | | | | |
+--------+ +--------+ +--------+ +--------+
Figure 8: Figure 8: Diagram of the process of refreshing an Figure 8: Diagram of the Process of Refreshing an Expired Access
access token Token
1. The client instance requests access to the resource (Section 2). * (1) The client instance requests access to the resource
(Section 2).
2. The AS grants access to the resource (Section 3) with an access * (2) The AS grants access to the resource (Section 3) with an
token (Section 3.2) usable at the RS. The access token response access token (Section 3.2) usable at the RS. The access token
includes a token management URI. response includes a token management URI.
3. The client instance uses the access token (Section 7.2) to call * (3) The client instance uses the access token (Section 7.2) to
the RS. call the RS.
4. The RS validates the access token and returns an appropriate * (4) The RS validates the access token and returns an appropriate
response for the API. response for the API.
5. Time passes and the client instance uses the access token to call * (5) Time passes and the client instance uses the access token to
the RS again. call the RS again.
6. The RS validates the access token and determines that the access * (6) The RS validates the access token and determines that the
token is expired. The RS responds to the client instance with an access token is expired. The RS responds to the client instance
error. with an error.
7. The client instance calls the token management URI returned in * (7) The client instance calls the token management URI returned in
(2) to rotate the access token (Section 6.1). The client (2) to rotate the access token (Section 6.1). The client instance
instance uses the access token (Section 7.2) in this call as well uses the access token (Section 7.2) in this call as well as the
as the appropriate key, see the token rotation section for appropriate key; see Section 6.1 for details.
details.
8. The AS validates the rotation request including the signature and * (8) The AS validates the rotation request, including the signature
keys presented in (7) and refreshes the access token and keys presented in (7), and refreshes the access token
(Section 3.2.1). The response includes a new version of the (Section 3.2.1). The response includes a new version of the
access token and can also include updated token management access token and can also include updated token management
information, which the client instance will store in place of the information, which the client instance will store in place of the
values returned in (2). values returned in (2).
1.6.7. Requesting Subject Information Only 1.6.7. Requesting Subject Information Only
In this scenario, the client instance does not call an RS and does In this scenario, the client instance does not call an RS and does
not request an access token. Instead, the client instance only not request an access token. Instead, the client instance only
requests and is returned direct subject information (Section 3.4). requests and is returned direct subject information (Section 3.4).
Many different interaction modes can be used in this scenario, so Many different interaction modes can be used in this scenario, so
these are shown only in the abstract as functions of the AS here. these are shown only in the abstract as functions of the AS here.
+--------+ +--------+ .----. +--------+ +--------+ .----.
skipping to change at page 30, line 49 skipping to change at line 1346
| | | | AuthZ +------+ | | | | AuthZ +------+
| | | | | End | | | | | | End |
| |<=(6)== Signal Continuation =========================+ User | | |<=(6)== Signal Continuation =========================+ User |
| | | | `----` | | | | `----`
| +--(7)--- Continue Request ------->| | | +--(7)--- Continue Request ------->| |
| | | | | | | |
| |<-(8)----- Grant Access ----------+ | | |<-(8)----- Grant Access ----------+ |
| | | | | | | |
+--------+ +--------+ +--------+ +--------+
Figure 9: Figure 9: Diagram of the process of requesting and Figure 9: Diagram of the Process of Requesting and Releasing Subject
releasing subject information apart from access tokens Information apart from Access Tokens
1. The client instance requests access to subject information * (1) The client instance requests access to subject information
(Section 2). (Section 2).
2. The AS determines that interaction is needed and responds * (2) The AS determines that interaction is needed and responds
(Section 3) with appropriate information for facilitating user (Section 3) with appropriate information for facilitating user
interaction (Section 3.3). interaction (Section 3.3).
3. The client instance facilitates the user interacting with the AS * (3) The client instance facilitates the user interacting with the
(Section 4) as directed in (2). AS (Section 4) as directed in (2).
4. The user authenticates at the AS, taking on the role of the RO. * (4) The user authenticates at the AS, taking on the role of the
RO.
5. As the RO, the user authorizes the pending request from the * (5) As the RO, the user authorizes the pending request from the
client instance. client instance.
6. When the AS is done interacting with the user, the AS returns the * (6) When the AS is done interacting with the user, the AS returns
user to the client instance and signals continuation. the user to the client instance and signals continuation.
7. The client instance loads the continuation information from (2) * (7) The client instance loads the continuation information from
and calls the AS to continue the request (Section 5). (2) and calls the AS to continue the request (Section 5).
8. If the request has been authorized, the AS grants access to the * (8) If the request has been authorized, the AS grants access to
requested direct subject information (Section 3.4) to the client the requested direct subject information (Section 3.4) to the
instance. At this stage, the user is generally considered client instance. At this stage, the user is generally considered
"logged in" to the client instance based on the identifiers and "logged in" to the client instance based on the identifiers and
assertions provided by the AS. Note that the AS can restrict the assertions provided by the AS. Note that the AS can restrict the
subject information returned and it might not match what the subject information returned, and it might not match what the
client instance requested, see the section on subject information client instance requested; see Section 3.4 for details.
for details.
1.6.8. Cross-User Authentication 1.6.8. Cross-User Authentication
In this scenario, the end user and resource owner are two different In this scenario, the end user and RO are two different people.
people. Here, the client instance already knows who the end user is, Here, the client instance already knows who the end user is, likely
likely through a separate authentication process. The end user, through a separate authentication process. The end user, operating
operating the client instance, needs to get subject information about the client instance, needs to get subject information about another
another person in the system, the RO. The RO is given an opportunity person in the system, the RO. The RO is given an opportunity to
to release this information using an asynchronous interaction method release this information using an asynchronous interaction method
with the AS. This scenario would apply, for instance, when the end with the AS. This scenario would apply, for instance, when the end
user is an agent in a call-center and the resource owner is a user is an agent in a call center and the RO is a customer
customer authorizing the call center agent to access their account on authorizing the call-center agent to access their account on their
their behalf. behalf.
.----. .----. .----. .----.
| End | | RO | | End | | RO |
| User |<=================(1)== Identify RO ==================>| | | User |<=================(1)== Identify RO ==================>| |
| | | | | | | |
| | +--------+ +--------+ | | | | +--------+ +--------+ | |
| +==(2)==>| Client | | AS | | | | +==(2)==>| Client | | AS | | |
| | RO ID |Instance| | | | | | | RO ID |Instance| | | | |
| | | | | | | | | | | | | | | |
| | | +--(3)-- Req. ---->| | | | | | | +--(3)-- Req. ---->| | | |
skipping to change at page 32, line 34 skipping to change at line 1421
| | | | | | | | | | | | | | | |
| | | +--(9)--- Cont. -->| | | | | | | +--(9)--- Cont. -->| | | |
| | | | | | | | | | | | | | | |
| | | |<-(10)-- Subj. ---+ | | | | | | |<-(10)-- Subj. ---+ | | |
| |<=(11)==+ | Info | | | | | |<=(11)==+ | Info | | | |
| | Return | | | | | | | | Return | | | | | |
| | RO | | | | | | | | RO | | | | | |
| | Info | | | | | | | | Info | | | | | |
`----` +--------+ +--------+ `----` `----` +--------+ +--------+ `----`
Figure 10: Figure 10: Diagram of cross-user authorization, where Figure 10: Diagram of Cross-User Authorization, Where the End
the end user and RO are different User and RO Are Different
Precondition: The end user is authenticated to the client instance, Precondition: The end user is authenticated to the client instance,
and the client instance has an identifier representing the end user and the client instance has an identifier representing the end user
that it can present to the AS. This identifier should be unique to that it can present to the AS. This identifier should be unique to
the particular session with the client instance and the AS. The the particular session with the client instance and the AS. The
client instance is also known to the AS and allowed to access this client instance is also known to the AS and allowed to access this
advanced functionality where the information of someone other than advanced functionality where the information of someone other than
the end user is returned to the client instance. the end user is returned to the client instance.
1. The RO communicates a human-readable identifier to the end user, * (1) The RO communicates a human-readable identifier to the end
such as an email address or account number. This communication user, such as an email address or account number. This
happens out of band from the protocol, such as over the phone communication happens out of band from the protocol, such as over
between parties. Note that the RO is not interacting with the the phone between parties. Note that the RO is not interacting
client instance. with the client instance.
2. The end user communicates the identifier to the client instance. * (2) The end user communicates the identifier to the client
The means by which the identifier is communicated to the client instance. The means by which the identifier is communicated to
instance is out of scope for this specification. the client instance are out of scope for this specification.
3. The client instance requests access to subject information * (3) The client instance requests access to subject information
(Section 2). The request includes the RO's identifier in the (Section 2). The request includes the RO's identifier in the
subject information request (Section 2.2) sub_ids field, and the sub_ids field of the subject information request (Section 2.2) and
end user's identifier in the user information field the end user's identifier in the user field (Section 2.4). The
(Section 2.4) of the request. The request includes no request includes no interaction start methods, since the end user
interaction start methods, since the end user is not expected to is not expected to be the one interacting with the AS. The
be the one interacting with the AS. The request does include request does include the push-based interaction finish method
the push based interaction finish method (Section 2.5.2.2) to (Section 2.5.2.2) to allow the AS to signal to the client instance
allow the AS to signal to the client instance when the when the interaction with the RO has concluded.
interaction with the RO has concluded.
4. The AS sees that the identifier for the end user and subject * (4) The AS sees that the identifiers for the end user and subject
being requested are different. The AS determines that it can being requested are different. The AS determines that it can
reach out to the RO asynchronously for approval. While it is reach out to the RO asynchronously for approval. While it is
doing so, the AS returns a continuation response (Section 3.1) doing so, the AS returns a continuation response (Section 3.1)
with a finish nonce to allow the client instance to continue the with a finish nonce to allow the client instance to continue the
grant request after interaction with the RO has concluded. grant request after interaction with the RO has concluded.
5. The AS contacts the RO and has them authenticate to the system. * (5) The AS contacts the RO and has them authenticate to the
The means for doing this are outside the scope of this system. The means for doing this are outside the scope of this
specification, but the identity of the RO is known from the specification, but the identity of the RO is known from the
subject identifier sent in (3). Subject Identifier sent in (3).
6. The RO is prompted to authorize the end user's request via the * (6) The RO is prompted to authorize the end user's request via the
client instance. Since the end user was identified in (3) via client instance. Since the end user was identified in (3) via the
the user field, the AS can show this information to the RO user field, the AS can show this information to the RO during the
during the authorization request. authorization request.
7. The RO completes the authorization with the AS. The AS marks * (7) The RO completes the authorization with the AS. The AS marks
the request as _approved_. the request as _approved_.
8. The RO pushes the interaction finish message (Section 4.2.2) to * (8) The RO pushes the interaction finish message (Section 4.2.2)
the client instance. Note that in the case the RO cannot be to the client instance. Note that in the case the RO cannot be
reached or the RO denies the request, the AS still sends the reached or the RO denies the request, the AS still sends the
interaction finish message to the client instance, after which interaction finish message to the client instance, after which the
the client instance can negotiate next steps if possible. client instance can negotiate next steps if possible.
9. The client instance validates the interaction finish message and * (9) The client instance validates the interaction finish message
continues the grant request (Section 5.1). and continues the grant request (Section 5.1).
10. The AS returns the RO's subject information (Section 3.4) to the * (10) The AS returns the RO's subject information (Section 3.4) to
client instance. the client instance.
11. The client instance can display or otherwise utilize the RO's * (11) The client instance can display or otherwise utilize the RO's
user information in its session with the end user. Note that user information in its session with the end user. Note that
since the client instance requested different sets of user since the client instance requested different sets of user
information in (3), the client instance does not conflate the information in (3), the client instance does not conflate the end
end user with the RO. user with the RO.
Additional considerations for asynchronous interactions like this are Additional considerations for asynchronous interactions like this are
discussed in Section 13.36. discussed in Section 11.36.
2. Requesting Access 2. Requesting Access
To start a request, the client instance sends an HTTP POST with a To start a request, the client instance sends an HTTP POST with a
JSON [RFC8259] document to the grant endpoint of the AS. The grant JSON [RFC8259] document to the grant endpoint of the AS. The grant
endpoint is a URI that uniquely identifies the AS to client instances endpoint is a URI that uniquely identifies the AS to client instances
and serves as the identifier for the AS. The document is a JSON and serves as the identifier for the AS. The document is a JSON
object where each field represents a different aspect of the client object where each field represents a different aspect of the client
instance's request. Each field is described in detail in a section instance's request. Each field is described in detail in a
below. subsection below.
access_token (object / array of objects): Describes the rights and access_token (object / array of objects): Describes the rights and
properties associated with the requested access token. REQUIRED properties associated with the requested access token. REQUIRED
if requesting an access token. See Section 2.1. if requesting an access token. See Section 2.1.
subject (object): Describes the information about the RO that the subject (object): Describes the information about the RO that the
client instance is requesting to be returned directly in the client instance is requesting to be returned directly in the
response from the AS. REQUIRED if requesting subject information. response from the AS. REQUIRED if requesting subject information.
See Section 2.2. See Section 2.2.
client (object / string): Describes the client instance that is client (object / string): Describes the client instance that is
making this request, including the key that the client instance making this request, including the key that the client instance
will use to protect this request and any continuation requests at will use to protect this request, any continuation requests at the
the AS and any user-facing information about the client instance AS, and any user-facing information about the client instance used
used in interactions. REQUIRED. See Section 2.3. in interactions. REQUIRED. See Section 2.3.
user (object / string): Identifies the end user to the AS in a user (object / string): Identifies the end user to the AS in a
manner that the AS can verify, either directly or by interacting manner that the AS can verify, either directly or by interacting
with the end user to determine their status as the RO. OPTIONAL. with the end user to determine their status as the RO. OPTIONAL.
See Section 2.4. See Section 2.4.
interact (object): Describes the modes that the client instance interact (object): Describes the modes that the client instance
supports for allowing the RO to interact with the AS and modes for supports for allowing the RO to interact with the AS and modes for
the client instance to receive updates when interaction is the client instance to receive updates when interaction is
complete. REQUIRED if interaction is supported. See Section 2.5. complete. REQUIRED if interaction is supported. See Section 2.5.
Additional members of this request object can be defined by Additional members of this request object can be defined by
extensions using the GNAP Grant Request Parameters Registry extensions using the "GNAP Grant Request Parameters" registry
(Section 11.3). (Section 10.3).
A non-normative example of a grant request is below: A non-normative example of a grant request is below:
{ {
"access_token": { "access_token": {
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read", "read",
skipping to change at page 36, line 13 skipping to change at line 1589
}, },
"subject": { "subject": {
"sub_id_formats": ["iss_sub", "opaque"], "sub_id_formats": ["iss_sub", "opaque"],
"assertion_formats": ["id_token"] "assertion_formats": ["id_token"]
} }
} }
Sending a request to the grant endpoint creates a grant request in Sending a request to the grant endpoint creates a grant request in
the _processing_ state. The AS processes this request to determine the _processing_ state. The AS processes this request to determine
whether interaction or authorization are necessary (moving to the whether interaction or authorization are necessary (moving to the
_pending_ state), or if access can be granted immediately (moving to _pending_ state) or if access can be granted immediately (moving to
the _approved_ state). the _approved_ state).
The request MUST be sent as a JSON object in the content of the HTTP The request MUST be sent as a JSON object in the content of the HTTP
POST request with Content-Type application/json. A key proofing POST request with Content-Type application/json. A key proofing
mechanism MAY define an alternative content type, as long as the mechanism MAY define an alternative content type, as long as the
content is formed from the JSON object. For example, the attached content is formed from the JSON object. For example, the attached
JWS key proofing mechanism (see Section 7.3.4) places the JSON object JSON Web Signature (JWS) key proofing mechanism (see Section 7.3.4)
into the payload of a JWS wrapper, which is in turn sent as the places the JSON object into the payload of a JWS wrapper, which is in
message content. turn sent as the message content.
2.1. Requesting Access to Resources 2.1. Requesting Access to Resources
If the client instance is requesting one or more access tokens for If the client instance is requesting one or more access tokens for
the purpose of accessing an API, the client instance MUST include an the purpose of accessing an API, the client instance MUST include an
access_token field. This field MUST be an object (for a single access_token field. This field MUST be an object (for a single
access token (Section 2.1.1)) or an array of these objects (for access token (Section 2.1.1)) or an array of these objects (for
multiple access tokens (Section 2.1.2)), as described in the multiple access tokens (Section 2.1.2)), as described in the
following sections. following subsections.
2.1.1. Requesting a Single Access Token 2.1.1. Requesting a Single Access Token
To request a single access token, the client instance sends an To request a single access token, the client instance sends an
access_token object composed of the following fields. access_token object composed of the following fields.
access (array of objects/strings): Describes the rights that the access (array of objects/strings): Describes the rights that the
client instance is requesting for the access token to be used at client instance is requesting for the access token to be used at
the RS. REQUIRED. See Section 8. the RS. REQUIRED. See Section 8.
label (string): A unique name chosen by the client instance to refer label (string): A unique name chosen by the client instance to refer
to the resulting access token. The value of this field is opaque to the resulting access token. The value of this field is opaque
to the AS and is not intended to be exposed to or used by the end to the AS and is not intended to be exposed to or used by the end
user. If this field is included in the request, the AS MUST user. If this field is included in the request, the AS MUST
include the same label in the token response (Section 3.2). include the same label in the token response (Section 3.2).
REQUIRED if used as part of a multiple access token request REQUIRED if used as part of a request for multiple access tokens
(Section 2.1.2), OPTIONAL otherwise. (Section 2.1.2); OPTIONAL otherwise.
flags (array of strings): A set of flags that indicate desired flags (array of strings): A set of flags that indicate desired
attributes or behavior to be attached to the access token by the attributes or behavior to be attached to the access token by the
AS. OPTIONAL. AS. OPTIONAL.
The values of the flags field defined by this specification are as The values of the flags field defined by this specification are as
follows: follows:
"bearer": If this flag is included, the access token being requested "bearer": If this flag is included, the access token being requested
is a bearer token. If this flag is omitted, the access token is is a bearer token. If this flag is omitted, the access token is
bound to the key used by the client instance in this request (or bound to the key used by the client instance in this request (or
that key's most recent rotation) and the access token MUST be that key's most recent rotation), and the access token MUST be
presented using the same key and proofing method. Methods for presented using the same key and proofing method. Methods for
presenting bound and bearer access tokens are described in presenting bound and bearer access tokens are described in
Section 7.2. See Section 13.9 for additional considerations on Section 7.2. See Section 11.9 for additional considerations on
the use of bearer tokens. the use of bearer tokens.
Flag values MUST NOT be included more than once. If the request Flag values MUST NOT be included more than once. If the request
includes a flag value multiple times, the AS MUST return an includes a flag value multiple times, the AS MUST return an
invalid_flag error defined in Section 3.6. invalid_flag error defined in Section 3.6.
Additional flags can be defined by extensions using the GNAP Access Additional flags can be defined by extensions using the "GNAP Access
Token Flags Registry (Section 11.4). Token Flags" registry (Section 10.4).
In the following non-normative example, the client instance is In the following non-normative example, the client instance is
requesting access to a complex resource described by a pair of access requesting access to a complex resource described by a pair of access
request object. request object.
"access_token": { "access_token": {
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
skipping to change at page 38, line 43 skipping to change at line 1691
"data", "data",
"pictures", "pictures",
"walrus whiskers" "walrus whiskers"
] ]
} }
], ],
"label": "token1-23" "label": "token1-23"
} }
If access is approved, the resulting access token is valid for the If access is approved, the resulting access token is valid for the
described resource. Since the "bearer" flag is not provided in this described resource. Since the bearer flag is not provided in this
example, the token is bound to the client instance's key (or its most example, the token is bound to the client instance's key (or its most
recent rotation). The token is labeled "token1-23". The token recent rotation). The token is labeled "token1-23". The token
response structure is described in Section 3.2.1. response structure is described in Section 3.2.1.
2.1.2. Requesting Multiple Access Tokens 2.1.2. Requesting Multiple Access Tokens
To request multiple access tokens to be returned in a single To request that multiple access tokens be returned in a single
response, the client instance sends an array of objects as the value response, the client instance sends an array of objects as the value
of the access_token parameter. Each object MUST conform to the of the access_token parameter. Each object MUST conform to the
request format for a single access token request, as specified in request format for a single access token request, as specified in
requesting a single access token (Section 2.1.1). Additionally, each Section 2.1.1. Additionally, each object in the array MUST include
object in the array MUST include the label field, and all values of the label field, and all values of these fields MUST be unique within
these fields MUST be unique within the request. If the client the request. If the client instance does not include a label value
instance does not include a label value for any entry in the array, for any entry in the array or the values of the label field are not
or the values of the label field are not unique within the array, the unique within the array, the AS MUST return an "invalid_request"
AS MUST return an "invalid_request" error (Section 3.6). error (Section 3.6).
The following non-normative example shows a request for two separate The following non-normative example shows a request for two separate
access tokens, token1 and token2. access tokens: token1 and token2.
"access_token": [ "access_token": [
{ {
"label": "token1", "label": "token1",
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read", "read",
"write", "write",
skipping to change at page 41, line 4 skipping to change at line 1757
"datatypes": [ "datatypes": [
"data", "data",
"pictures", "pictures",
"walrus whiskers" "walrus whiskers"
] ]
} }
], ],
"flags": [ "bearer" ] "flags": [ "bearer" ]
} }
] ]
All approved access requests are returned in the multiple access
token response (Section 3.2.2) structure using the values of the All approved access requests are returned in the response structure
for multiple access tokens (Section 3.2.2) using the values of the
label fields in the request. label fields in the request.
2.2. Requesting Subject Information 2.2. Requesting Subject Information
If the client instance is requesting information about the RO from If the client instance is requesting information about the RO from
the AS, it sends a subject field as a JSON object. This object MAY the AS, it sends a subject field as a JSON object. This object MAY
contain the following fields. contain the following fields.
sub_id_formats (array of strings): An array of subject identifier sub_id_formats (array of strings): An array of Subject Identifier
subject formats requested for the RO, as defined by [RFC9493]. subject formats requested for the RO, as defined by [RFC9493].
REQUIRED if subject identifiers are requested. REQUIRED if Subject Identifiers are requested.
assertion_formats (array of strings): An array of requested assertion_formats (array of strings): An array of requested
assertion formats. Possible values include id_token for an OpenID assertion formats. Possible values include id_token for an OpenID
Connect ID Token ([OIDC]) and saml2 for a SAML 2 assertion Connect ID Token [OIDC] and saml2 for a Security Assertion Markup
([SAML2]). Additional assertion formats are defined by the GNAP Language (SAML) 2 assertion [SAML2]. Additional assertion formats
Assertion Formats Registry (Section 11.6). REQUIRED if assertions can be defined in the "GNAP Assertion Formats" registry
are requested. (Section 10.6). REQUIRED if assertions are requested.
sub_ids (array of objects): An array of subject identifiers sub_ids (array of objects): An array of Subject Identifiers
representing the subject for which information is being requested. representing the subject for which information is being requested.
Each object is a subject identifier as defined by [RFC9493]. All Each object is a Subject Identifier as defined by [RFC9493]. All
identifiers in the sub_ids array MUST identify the same subject. identifiers in the sub_ids array MUST identify the same subject.
If omitted, the AS SHOULD assume that subject information requests If omitted, the AS SHOULD assume that subject information requests
are about the current user and SHOULD require direct interaction are about the current user and SHOULD require direct interaction
or proof of presence before releasing information. OPTIONAL. or proof of presence before releasing information. OPTIONAL.
Additional fields are defined in the GNAP Subject Information Request Additional fields can be defined in the "GNAP Subject Information
Fields Registry (Section 11.5). Request Fields" registry (Section 10.5).
"subject": { "subject": {
"sub_id_formats": [ "iss_sub", "opaque" ], "sub_id_formats": [ "iss_sub", "opaque" ],
"assertion_formats": [ "id_token", "saml2" ] "assertion_formats": [ "id_token", "saml2" ]
} }
The AS can determine the RO's identity and permission for releasing The AS can determine the RO's identity and permission for releasing
this information through interaction with the RO (Section 4), AS this information through interaction with the RO (Section 4), AS
policies, or assertions presented by the client instance policies, or assertions presented by the client instance
(Section 2.4). If this is determined positively, the AS MAY return (Section 2.4). If this is determined positively, the AS MAY return
the RO's information in its response (Section 3.4) as requested. the RO's information in its response (Section 3.4) as requested.
Subject identifier types requested by the client instance serve only Subject Identifier types requested by the client instance serve only
to identify the RO in the context of the AS and can't be used as to identify the RO in the context of the AS and can't be used as
communication channels by the client instance, as discussed in communication channels by the client instance, as discussed in
Section 3.4. Section 3.4.
2.3. Identifying the Client Instance 2.3. Identifying the Client Instance
When sending new grant request to the AS, the client instance MUST When sending a new grant request to the AS, the client instance MUST
identify itself by including its client information in the client identify itself by including its client information in the client
field of the request and by signing the request with its unique key field of the request and by signing the request with its unique key
as described in Section 7.3. Note that once a grant has been created as described in Section 7.3. Note that once a grant has been created
and is in the _pending_ or _accepted_ states, the AS can determine and is in either the _pending_ or the _approved_ state, the AS can
which client is associated with the grant by dereferencing the determine which client is associated with the grant by dereferencing
continuation access token sent in the continuation request the continuation access token sent in the continuation request
(Section 5). As a consequence, the client field is not sent or (Section 5). As a consequence, the client field is not sent or
accepted for continuation requests. accepted for continuation requests.
Client information is sent by value as an object or by reference as a Client information is sent by value as an object or by reference as a
string (see Section 2.3.1). string (see Section 2.3.1).
When client instance information is sent by value, the client field When client instance information is sent by value, the client field
of the request consists of a JSON object with the following fields. of the request consists of a JSON object with the following fields.
key (object / string): The public key of the client instance to be key (object / string): The public key of the client instance to be
used in this request as described in Section 7.1 or a reference to used in this request as described in Section 7.1 or a reference to
a key as described in Section 7.1.1. REQUIRED. a key as described in Section 7.1.1. REQUIRED.
class_id (string): An identifier string that the AS can use to class_id (string): An identifier string that the AS can use to
identify the client software comprising this client instance. The identify the client software comprising this client instance. The
contents and format of this field are up to the AS. OPTIONAL. contents and format of this field are up to the AS. OPTIONAL.
display (object): An object containing additional information that display (object): An object containing additional information that
the AS MAY display to the RO during interaction, authorization, the AS MAY display to the RO during interaction, authorization,
and management. OPTIONAL. (Section 2.3.2) and management. OPTIONAL. See Section 2.3.2.
"client": { "client": {
"key": { "key": {
"proof": "httpsig", "proof": "httpsig",
"jwk": { "jwk": {
"kty": "RSA", "kty": "RSA",
"e": "AQAB", "e": "AQAB",
"kid": "xyz-1", "kid": "xyz-1",
"alg": "RS256", "alg": "RS256",
"n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8..." "n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8..."
} }
}, },
"class_id": "web-server-1234", "class_id": "web-server-1234",
"display": { "display": {
"name": "My Client Display Name", "name": "My Client Display Name",
"uri": "https://example.net/client" "uri": "https://example.net/client"
} }
} }
Additional fields are defined in the GNAP Client Instance Fields
Registry (Section 11.7). Additional fields can be defined in the "GNAP Client Instance Fields"
registry (Section 10.7).
Absent additional attestations, profiles, or trust mechanisms, both Absent additional attestations, profiles, or trust mechanisms, both
the display and class_id fields are self-declarative, presented by the display and class_id fields are self-declarative, presented by
the client instance. The AS needs to exercise caution in their the client instance. The AS needs to exercise caution in their
interpretation, taking them as a hint but not as absolute truth. The interpretation, taking them as a hint but not as absolute truth. The
class_id field can be used in a variety of ways to help the AS make class_id field can be used in a variety of ways to help the AS make
sense of the particular context in which the client instance is sense of the particular context in which the client instance is
operating. In corporate environments, for example, different levels operating. In corporate environments, for example, different levels
of trust might apply depending on security policies. This field aims of trust might apply depending on security policies. This field aims
to help the AS adjust its own access decisions for different classes to help the AS adjust its own access decisions for different classes
of client software. It is possible to configure a set of values and of client software. It is possible to configure a set of values and
rules during a pre-registration, and then have the client instances rules during a pre-registration and then have the client instances
provide them later in runtime as a hint to the AS. In other cases, provide them later in runtime as a hint to the AS. In other cases,
the client runs with a specific AS in mind, so a single hardcoded the client runs with a specific AS in mind, so a single hardcoded
value would acceptable (for instance, a set top box with a class_id value would be acceptable (for instance, a set-top box with a
claiming to be "FooBarTV version 4"). While the client instance may class_id claiming to be "FooBarTV version 4"). While the client
not have contacted the AS yet, the value of this class_id field can instance may not have contacted the AS yet, the value of this
be evaluated by the AS according to a broader context of dynamic use, class_id field can be evaluated by the AS according to a broader
alongside other related information available elsewhere (for context of dynamic use, alongside other related information available
instance, corresponding fields in a certificate). If the AS is not elsewhere (for instance, corresponding fields in a certificate). If
able to interpret or validate the class_id field, it MUST either the AS is not able to interpret or validate the class_id field, it
return an invalid_client error (Section 3.6) or interpret the request MUST either return an invalid_client error (Section 3.6) or interpret
as if the class_id were not present. See additional discussion of the request as if the class_id were not present. See additional
client instance impersonation in Section 13.15. discussion of client instance impersonation in Section 11.15.
The client instance MUST prove possession of any presented key by the The client instance MUST prove possession of any presented key by the
proof mechanism associated with the key in the request. Key proofing proofing mechanism associated with the key in the request. Key
methods are defined in the GNAP Key Proofing Methods Registry proofing methods are defined in the "GNAP Key Proofing Methods"
(Section 11.16) and an initial set of methods is described in registry (Section 10.16), and an initial set of methods is described
Section 7.3. in Section 7.3.
If the same public key is sent by value on different access requests, If the same public key is sent by value on different access requests,
the AS MUST treat these requests as coming from the same client the AS MUST treat these requests as coming from the same client
instance for purposes of identification, authentication, and policy instance for purposes of identification, authentication, and policy
application. application.
If the AS does not know the client instance's public key ahead of If the AS does not know the client instance's public key ahead of
time, the AS can choose how to process the unknown key. Common time, the AS can choose how to process the unknown key. Common
approaches include: approaches include:
skipping to change at page 44, line 11 skipping to change at line 1908
* Limiting the client's requested access to only certain APIs and * Limiting the client's requested access to only certain APIs and
information information
* Denying the request entirely by returning an invalid_client error * Denying the request entirely by returning an invalid_client error
(Section 3.6) (Section 3.6)
The client instance MUST NOT send a symmetric key by value in the key The client instance MUST NOT send a symmetric key by value in the key
field of the request, as doing so would expose the key directly field of the request, as doing so would expose the key directly
instead of simply proving possession of it. See considerations on instead of simply proving possession of it. See considerations on
symmetric keys in Section 13.7. To use symmetric keys, the client symmetric keys in Section 11.7. To use symmetric keys, the client
instance can send the key by reference (Section 7.1.1) or send the instance can send the key by reference (Section 7.1.1) or send the
entire client identity by reference (Section 2.3.1). entire client identity by reference (Section 2.3.1).
The client instance's key can be pre-registered with the AS ahead of The client instance's key can be pre-registered with the AS ahead of
time and associated with a set of policies and allowable actions time and associated with a set of policies and allowable actions
pertaining to that client. If this pre-registration includes other pertaining to that client. If this pre-registration includes other
fields that can occur in the client request object described in this fields that can occur in the client request object described in this
section, such as class_id or display, the pre-registered values MUST section, such as class_id or display, the pre-registered values MUST
take precedence over any values given at runtime. Additional fields take precedence over any values given at runtime. Additional fields
sent during a request but not present in a pre-registered client sent during a request but not present in a pre-registered client
instance record at the AS SHOULD NOT be added to the client's pre- instance record at the AS SHOULD NOT be added to the client's pre-
registered record. See additional considerations regarding client registered record. See additional considerations regarding client
instance impersonation in Section 13.15. instance impersonation in Section 11.15.
A client instance that is capable of talking to multiple AS's SHOULD A client instance that is capable of talking to multiple ASes SHOULD
use a different key for each AS to prevent a class of mix-up attacks use a different key for each AS to prevent a class of mix-up attacks
as described in Section 13.31 unless other mechanisms can be used to as described in Section 11.31, unless other mechanisms can be used to
assure the identity of the AS for a given request. assure the identity of the AS for a given request.
2.3.1. Identifying the Client Instance by Reference 2.3.1. Identifying the Client Instance by Reference
If the client instance has an instance identifier that the AS can use If the client instance has an instance identifier that the AS can use
to determine appropriate key information, the client instance can to determine appropriate key information, the client instance can
send this instance identifier as a direct reference value in lieu of send this instance identifier as a direct reference value in lieu of
the client object. The instance identifier MAY be assigned to a the client object. The instance identifier MAY be assigned to a
client instance at runtime through a grant response (Section 3.5) or client instance at runtime through a grant response (Section 3.5) or
MAY be obtained in another fashion, such as a static registration MAY be obtained in another fashion, such as a static registration
skipping to change at page 45, line 17 skipping to change at line 1959
If the client instance has additional information to display to the If the client instance has additional information to display to the
RO during any interactions at the AS, it MAY send that information in RO during any interactions at the AS, it MAY send that information in
the "display" field. This field is a JSON object that declares the "display" field. This field is a JSON object that declares
information to present to the RO during any interactive sequences. information to present to the RO during any interactive sequences.
name (string): Display name of the client software. RECOMMENDED. name (string): Display name of the client software. RECOMMENDED.
uri (string): User-facing information about the client software, uri (string): User-facing information about the client software,
such as a web page. This URI MUST be an absolute URI. OPTIONAL. such as a web page. This URI MUST be an absolute URI. OPTIONAL.
logo_uri (string) Display image to represent the client software. logo_uri (string): Display image to represent the client software.
This URI MUST be an absolute URI. The logo MAY be passed by value This URI MUST be an absolute URI. The logo MAY be passed by value
by using a data: URI [RFC2397] referencing an image mediatype. by using a data: URI [RFC2397] referencing an image media type.
OPTIONAL. OPTIONAL.
"display": { "display": {
"name": "My Client Display Name", "name": "My Client Display Name",
"uri": "https://example.net/client", "uri": "https://example.net/client",
"logo_uri": "data:image/png;base64,Eeww...=" "logo_uri": "data:image/png;base64,Eeww...="
} }
Additional display fields are defined by the GNAP Client Instance Additional display fields can be defined in the "GNAP Client Instance
Display Fields Registry (Section 11.8). Display Fields" registry (Section 10.8).
The AS SHOULD use these values during interaction with the RO. The The AS SHOULD use these values during interaction with the RO. The
values are for informational purposes only and MUST NOT be taken as values are for informational purposes only and MUST NOT be taken as
authentic proof of the client instance's identity or source. The AS authentic proof of the client instance's identity or source. The AS
MAY restrict display values to specific client instances, as MAY restrict display values to specific client instances, as
identified by their keys in Section 2.3. See additional identified by their keys in Section 2.3. See additional
considerations for displayed client information in Section 13.15 and considerations for displayed client information in Section 11.15 and
for the logo_uri in particular in Section 13.16. for the logo_uri in particular in Section 11.16.
2.3.3. Authenticating the Client Instance 2.3.3. Authenticating the Client Instance
If the presented key is known to the AS and is associated with a If the presented key is known to the AS and is associated with a
single instance of the client software, the process of presenting a single instance of the client software, the process of presenting a
key and proving possession of that key is sufficient to authenticate key and proving possession of that key is sufficient to authenticate
the client instance to the AS. The AS MAY associate policies with the client instance to the AS. The AS MAY associate policies with
the client instance identified by this key, such as limiting which the client instance identified by this key, such as limiting which
resources can be requested and which interaction methods can be used. resources can be requested and which interaction methods can be used.
For example, only specific client instances with certain known keys For example, only specific client instances with certain known keys
might be trusted with access tokens without the AS interacting might be trusted with access tokens without the AS interacting
directly with the RO as in Appendix C.3. directly with the RO, as in Appendix B.3.
The presentation of a key allows the AS to strongly associate The presentation of a key allows the AS to strongly associate
multiple successive requests from the same client instance with each multiple successive requests from the same client instance with each
other. This is true when the AS knows the key ahead of time and can other. This is true when the AS knows the key ahead of time and can
use the key to authenticate the client instance, but also if the key use the key to authenticate the client instance, but it is also true
is ephemeral and created just for this series of requests. As such if the key is ephemeral and created just for this series of requests.
the AS MAY allow for client instances to make requests with unknown As such, the AS MAY allow for client instances to make requests with
keys. This pattern allows for ephemeral client instances, such as unknown keys. This pattern allows for ephemeral client instances
single-page applications, and client software with many individual (such as single-page applications) and client software with many
long-lived instances, such as mobile applications, to generate key individual long-lived instances (such as mobile applications) to
pairs per instance and use the keys within the protocol without generate key pairs per instance and use the keys within the protocol
having to go through a separate registration step. The AS MAY limit without having to go through a separate registration step. The AS
which capabilities are made available to client instances with MAY limit which capabilities are made available to client instances
unknown keys. For example, the AS could have a policy saying that with unknown keys. For example, the AS could have a policy saying
only previously-registered client instances can request particular that only previously registered client instances can request
resources, or that all client instances with unknown keys have to be particular resources or that all client instances with unknown keys
interactively approved by an RO. have to be interactively approved by an RO.
2.4. Identifying the User 2.4. Identifying the User
If the client instance knows the identity of the end user through one If the client instance knows the identity of the end user through one
or more identifiers or assertions, the client instance MAY send that or more identifiers or assertions, the client instance MAY send that
information to the AS in the "user" field. The client instance MAY information to the AS in the user field. The client instance MAY
pass this information by value or by reference (See Section 2.4.1). pass this information by value or by reference (see Section 2.4.1).
sub_ids (array of objects): An array of subject identifiers for the sub_ids (array of objects): An array of Subject Identifiers for the
end user, as defined by [RFC9493]. OPTIONAL. end user, as defined by [RFC9493]. OPTIONAL.
assertions (array of objects) An array containing assertions as assertions (array of objects): An array containing assertions as
objects each containing the assertion format and the assertion objects, each containing the assertion format and the assertion
value as the JSON string serialization of the assertion, as value as the JSON string serialization of the assertion, as
defined in Section 3.4. OPTIONAL. defined in Section 3.4. OPTIONAL.
"user": { "user": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
} ], } ],
"assertions": [ { "assertions": [ {
"format": "id_token", "format": "id_token",
"value": "eyj..." "value": "eyj..."
} ] } ]
} }
Subject identifiers are hints to the AS in determining the RO and Subject Identifiers are hints to the AS in determining the RO and
MUST NOT be taken as authoritative statements that a particular RO is MUST NOT be taken as authoritative statements that a particular RO is
present at the client instance and acting as the end user. present at the client instance and acting as the end user.
Assertions presented by the client instance SHOULD be validated by Assertions presented by the client instance SHOULD be validated by
the AS. While the details of such validation are outside the scope the AS. While the details of such validation are outside the scope
of this specification, common validation steps include verifying the of this specification, common validation steps include verifying the
signature of the assertion against a trusted signing key, verifying signature of the assertion against a trusted signing key, verifying
the audience and issuer of the assertion map to expected values, and the audience and issuer of the assertion map to expected values, and
verifying the time window for the assertion itself. However, note verifying the time window for the assertion itself. However, note
that in many use cases, some of these common steps are relaxed. For that in many use cases, some of these common steps are relaxed. For
example, an AS acting as an identity provider (IdP) could expect that example, an AS acting as an identity provider (IdP) could expect that
assertions being presented using this mechanism were issued by the AS assertions being presented using this mechanism were issued by the AS
to the client software. The AS would verify that the AS is the to the client software. The AS would verify that the AS is the
issuer of the assertion, not the audience, and that the client issuer of the assertion, not the audience, and that the client
instance is instead the audience of the assertion. Similarly, an AS instance is instead the audience of the assertion. Similarly, an AS
might accept a recently-expired assertion in order to help bootstrap might accept a recently expired assertion in order to help bootstrap
a new session with a specific end user. a new session with a specific end user.
If the identified end user does not match the RO present at the AS If the identified end user does not match the RO present at the AS
during an interaction step, and the AS is not explicitly allowing a during an interaction step and the AS is not explicitly allowing a
cross-user authorization, the AS SHOULD reject the request with an cross-user authorization, the AS SHOULD reject the request with an
unknown_user error (Section 3.6). unknown_user error (Section 3.6).
If the AS trusts the client instance to present verifiable assertions If the AS trusts the client instance to present verifiable assertions
or known subject identifiers, such as an opaque identifier issued by or known Subject Identifiers, such as an opaque identifier issued by
the AS for this specific client instance, the AS MAY decide, based on the AS for this specific client instance, the AS MAY decide, based on
its policy, to skip interaction with the RO, even if the client its policy, to skip interaction with the RO, even if the client
instance provides one or more interaction modes in its request. instance provides one or more interaction modes in its request.
See Section 13.30 for considerations that the AS has to make when See Section 11.30 for considerations for the AS when accepting and
accepting and processing assertions from the client instance. processing assertions from the client instance.
2.4.1. Identifying the User by Reference 2.4.1. Identifying the User by Reference
The AS can identify the current end user to the client instance with The AS can identify the current end user to the client instance with
a reference which can be used by the client instance to refer to the a reference that can be used by the client instance to refer to the
end user across multiple requests. If the client instance has a end user across multiple requests. If the client instance has a
reference for the end user at this AS, the client instance MAY pass reference for the end user at this AS, the client instance MAY pass
that reference as a string. The format of this string is opaque to that reference as a string. The format of this string is opaque to
the client instance. the client instance.
"user": "XUT2MFM1XBIKJKSDU8QM" "user": "XUT2MFM1XBIKJKSDU8QM"
One means of dynamically obtaining such a user reference is from the One means of dynamically obtaining such a user reference is from the
AS returning an opaque subject identifier as described in AS returning an opaque Subject Identifier as described in
Section 3.4. Other means of configuring a client instance with a Section 3.4. Other means of configuring a client instance with a
user identifier are out of scope of this specification. The lifetime user identifier are out of scope of this specification. The lifetime
and validity of these user references is determined by the AS and and validity of these user references are determined by the AS, and
this lifetime is not exposed to the client instance in GNAP. As this lifetime is not exposed to the client instance in GNAP. As
such, a client instance using such a user reference is likely to keep such, a client instance using such a user reference is likely to keep
using that reference until such a time as it stops working. using that reference until it stops working.
User reference identifiers are not intended to be human-readable user User reference identifiers are not intended to be human-readable user
identifiers or structured assertions. For the client instance to identifiers or structured assertions. For the client instance to
send either of these, the client can use the full user request object send either of these, the client can use the full user request object
(Section 2.4) instead. (Section 2.4) instead.
If the AS does not recognize the user reference, it MUST return an If the AS does not recognize the user reference, it MUST return an
unknown_user error (Section 3.6). unknown_user error (Section 3.6).
2.5. Interacting with the User 2.5. Interacting with the User
Often, the AS will require interaction with the RO (Section 4) in Often, the AS will require interaction with the RO (Section 4) in
order to approve a requested delegation to the client instance for order to approve a requested delegation to the client instance for
both access to resources and direct subject information. Many times both access to resources and direct subject information. Many times,
the end user using the client instance is the same person as the RO, the end user using the client instance is the same person as the RO,
and the client instance can directly drive interaction with the end and the client instance can directly drive interaction with the end
user by facilitating the process through means such as redirection to user by facilitating the process through means such as redirection to
a URI or launching an application. Other times, the client instance a URI or launching an application. Other times, the client instance
can provide information to start the RO's interaction on a secondary can provide information to start the RO's interaction on a secondary
device, or the client instance will wait for the RO to approve the device, or the client instance will wait for the RO to approve the
request asynchronously. The client instance could also be signaled request asynchronously. The client instance could also be signaled
that interaction has concluded through a callback mechanism. that interaction has concluded through a callback mechanism.
The client instance declares the parameters for interaction methods The client instance declares the parameters for interaction methods
skipping to change at page 48, line 41 skipping to change at line 2125
declare how the client can initiate and complete the request, as well declare how the client can initiate and complete the request, as well
as provide hints to the AS about user preferences such as locale. A as provide hints to the AS about user preferences such as locale. A
client instance MUST NOT declare an interaction mode it does not client instance MUST NOT declare an interaction mode it does not
support. The client instance MAY send multiple modes in the same support. The client instance MAY send multiple modes in the same
request. There is no preference order specified in this request. An request. There is no preference order specified in this request. An
AS MAY respond to any, all, or none of the presented interaction AS MAY respond to any, all, or none of the presented interaction
modes (Section 3.3) in a request, depending on its capabilities and modes (Section 3.3) in a request, depending on its capabilities and
what is allowed to fulfill the request. what is allowed to fulfill the request.
start (array of objects/strings): Indicates how the client instance start (array of objects/strings): Indicates how the client instance
can start an interaction. REQUIRED. (Section 2.5.1) can start an interaction. REQUIRED. See Section 2.5.1.
finish (object): Indicates how the client instance can receive an finish (object): Indicates how the client instance can receive an
indication that interaction has finished at the AS. OPTIONAL. indication that interaction has finished at the AS. OPTIONAL.
(Section 2.5.2) See Section 2.5.2.
hints (object): Provides additional information to inform the hints (object): Provides additional information to inform the
interaction process at the AS. OPTIONAL. (Section 2.5.3) interaction process at the AS. OPTIONAL. See Section 2.5.3.
In the following non-normative example, the client instance is In the following non-normative example, the client instance is
indicating that it can redirect (Section 2.5.1.1) the end user to an indicating that it can redirect (Section 2.5.1.1) the end user to an
arbitrary URI and can receive a redirect (Section 2.5.2.1) through a arbitrary URI and can receive a redirect (Section 2.5.2.1) through a
browser request. Note that the client instance does not accept a browser request. Note that the client instance does not accept a
push-style callback. The pattern of using a redirect for both push-style callback. The pattern of using a redirect for both
interaction start and finish is common for web-based client software. interaction start and finish is common for web-based client software.
"interact": { "interact": {
"start": ["redirect"], "start": ["redirect"],
"finish": { "finish": {
"method": "redirect", "method": "redirect",
"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
} }
In the following non-normative example, the client instance is In the following non-normative example, the client instance is
indicating that it can display a user code (Section 2.5.1.3) and indicating that it can display a user code (Section 2.5.1.3) and
direct the end user to an arbitrary URI (Section 2.5.1.1), but it direct the end user to an arbitrary URI (Section 2.5.1.1), but it
cannot accept a redirect or push callback. This pattern is common cannot accept a redirect or push-style callback. This pattern is
for devices with robust display capabilities but that expect the use common for devices that have robust display capabilities but expect
of a secondary device to facilitate end-user interaction with the AS, the use of a secondary device to facilitate end-user interaction with
such as a set-top box capable of displaying an interaction URL as a the AS, such as a set-top box capable of displaying an interaction
QR code. URL as a QR code.
"interact": { "interact": {
"start": ["redirect", "user_code"] "start": ["redirect", "user_code"]
} }
In the following non-normative example, the client instance is In the following non-normative example, the client instance is
indicating that it can not start any interaction with the end-user, indicating that it cannot start any interaction with the end user but
but that the AS can push an interaction finish message that the AS can push an interaction finish message (Section 2.5.2.2)
(Section 2.5.2.2) when authorization from the RO is received when authorization from the RO is received asynchronously. This
asynchronously. This pattern is common for scenarios where a service pattern is common for scenarios where a service needs to be
needs to be authorized, but the RO is able to be contacted separately authorized, but the RO is able to be contacted separately from the
from the GNAP transaction itself, such as through a push notification GNAP transaction itself, such as through a push notification or
or existing interactive session on a secondary device. existing interactive session on a secondary device.
"interact": { "interact": {
"start": [], "start": [],
"finish": { "finish": {
"method": "push", "method": "push",
"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
} }
If the client instance does not provide a suitable interaction
mechanism, the AS cannot contact the RO asynchronously, and the AS If all of the following conditions are true, the AS MUST return an
determines that interaction is required, then the AS MUST return an
invalid_interaction error (Section 3.6) since the client instance invalid_interaction error (Section 3.6) since the client instance
will be unable to complete the request without authorization. will be unable to complete the request without authorization:
* The client instance does not provide a suitable interaction
mechanism.
* The AS cannot contact the RO asynchronously.
* The AS determines that interaction is required.
2.5.1. Start Mode Definitions 2.5.1. Start Mode Definitions
If the client instance is capable of starting interaction with the If the client instance is capable of starting interaction with the
end user, the client instance indicates this by sending an array of end user, the client instance indicates this by sending an array of
start modes under the start key. Each interaction start modes has a start modes under the start key. Each interaction start mode has a
unique identifying name. Interaction start modes are specified in unique identifying name. Interaction start modes are specified in
the array either by a string, which consists of the start mode name the array either by a string, which consists of the start mode name
on its own, or by a JSON object with the required field mode: on its own, or by a JSON object with the required field mode:
mode: The interaction start mode. REQUIRED. mode: The interaction start mode. REQUIRED.
Interaction start modes defined as objects MAY define additional Interaction start modes defined as objects MAY define additional
parameters to be required in the object. parameters to be required in the object.
The start array can contain both string-type and object-type modes. The start array can contain both string-type and object-type modes.
This specification defines the following interaction start modes: This specification defines the following interaction start modes:
"redirect" (string): Indicates that the client instance can direct "redirect" (string): Indicates that the client instance can direct
the end user to an arbitrary URI for interaction. Section 2.5.1.1 the end user to an arbitrary URI for interaction. See
Section 2.5.1.1.
"app" (string): Indicates that the client instance can launch an "app" (string): Indicates that the client instance can launch an
application on the end user's device for interaction. application on the end user's device for interaction. See
Section 2.5.1.2 Section 2.5.1.2.
"user_code" (string): Indicates that the client instance can "user_code" (string): Indicates that the client instance can
communicate a human-readable short code to the end user for use communicate a short, human-readable code to the end user for use
with a stable URI. Section 2.5.1.3 with a stable URI. See Section 2.5.1.3.
"user_code_uri" (string): Indicates that the client instance can "user_code_uri" (string): Indicates that the client instance can
communicate a human-readable short code to the end user for use communicate a short, human-readable code to the end user for use
with a short, dynamic URI. Section 2.5.1.4 with a short, dynamic URI. See Section 2.5.1.4.
Additional start modes are defined in the GNAP Interaction Start Additional start modes can be defined in the "GNAP Interaction Start
Modes Registry (Section 11.9). Modes" registry (Section 10.9).
2.5.1.1. Redirect to an Arbitrary URI 2.5.1.1. Redirect to an Arbitrary URI
If the client instance is capable of directing the end user to a URI If the client instance is capable of directing the end user to a URI
defined by the AS at runtime, the client instance indicates this by defined by the AS at runtime, the client instance indicates this by
including redirect in the array under the start key. The means by including redirect in the array under the start key. The means by
which the client instance will activate this URI is out of scope of which the client instance will activate this URI are out of scope of
this specification, but common methods include an HTTP redirect, this specification, but common methods include an HTTP redirect,
launching a browser on the end user's device, providing a scannable launching a browser on the end user's device, providing a scannable
image encoding, and printing out a URI to an interactive console. image encoding, and printing out a URI to an interactive console.
While this URI is generally hosted at the AS, the client instance can While this URI is generally hosted at the AS, the client instance can
make no assumptions about its contents, composition, or relationship make no assumptions about its contents, composition, or relationship
to the grant endpoint URI. to the grant endpoint URI.
"interact": { "interact": {
"start": ["redirect"] "start": ["redirect"]
} }
If this interaction mode is supported for this client instance and If this interaction mode is supported for this client instance and
request, the AS returns a redirect interaction response request, the AS returns a redirect interaction response
Section 3.3.1. The client instance manages this interaction method (Section 3.3.1). The client instance manages this interaction method
as described in Section 4.1.1. as described in Section 4.1.1.
See Section 13.29 for more considerations regarding the use of front- See Section 11.29 for more considerations regarding the use of front-
channel communication techniques. channel communication techniques.
2.5.1.2. Open an Application-specific URI 2.5.1.2. Open an Application-Specific URI
If the client instance can open a URI associated with an application If the client instance can open a URI associated with an application
on the end user's device, the client instance indicates this by on the end user's device, the client instance indicates this by
including app in the array under the start key. The means by which including app in the array under the start key. The means by which
the client instance determines the application to open with this URI the client instance determines the application to open with this URI
are out of scope of this specification. are out of scope of this specification.
"interact": { "interact": {
"start": ["app"] "start": ["app"]
} }
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payload (Section 3.3.2). The client instance manages this payload (Section 3.3.2). The client instance manages this
interaction method as described in Section 4.1.4. interaction method as described in Section 4.1.4.
2.5.1.3. Display a Short User Code 2.5.1.3. Display a Short User Code
If the client instance is capable of displaying or otherwise If the client instance is capable of displaying or otherwise
communicating a short, human-entered code to the RO, the client communicating a short, human-entered code to the RO, the client
instance indicates this by including user_code in the array under the instance indicates this by including user_code in the array under the
start key. This code is to be entered at a static URI that does not start key. This code is to be entered at a static URI that does not
change at runtime. The client instance has no reasonable means to change at runtime. The client instance has no reasonable means to
communicate a dynamic URI to the RO, and so this URI is usually communicate a dynamic URI to the RO, so this URI is usually
communicated out of band to the RO through documentation or other communicated out of band to the RO through documentation or other
messaging outside of GNAP. While this URI is generally hosted at the messaging outside of GNAP. While this URI is generally hosted at the
AS, the client instance can make no assumptions about its contents, AS, the client instance can make no assumptions about its contents,
composition, or relationship to the grant endpoint URI. composition, or relationship to the grant endpoint URI.
"interact": { "interact": {
"start": ["user_code"] "start": ["user_code"]
} }
If this interaction mode is supported for this client instance and If this interaction mode is supported for this client instance and
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2.5.2. Interaction Finish Methods 2.5.2. Interaction Finish Methods
If the client instance is capable of receiving a message from the AS If the client instance is capable of receiving a message from the AS
indicating that the RO has completed their interaction, the client indicating that the RO has completed their interaction, the client
instance indicates this by sending the following members of an object instance indicates this by sending the following members of an object
under the finish key. under the finish key.
method (string): The callback method that the AS will use to contact method (string): The callback method that the AS will use to contact
the client instance. REQUIRED. the client instance. REQUIRED.
uri (string): Indicates the URI that the AS will either send the RO uri (string): Indicates the URI that the AS will use to signal the
to after interaction or send an HTTP POST request. This URI MAY client instance that interaction has completed. This URI MAY be
be unique per request and MUST be hosted by or accessible by the unique per request and MUST be hosted by or accessible to the
client instance. This URI MUST be an absolute URI, and MUST NOT client instance. This URI MUST be an absolute URI and MUST NOT
contain any fragment component. If the client instance needs any contain any fragment component. If the client instance needs any
state information to tie to the front channel interaction state information to tie to the front-channel interaction
response, it MUST use a unique callback URI to link to that response, it MUST use a unique callback URI to link to that
ongoing state. The allowable URIs and URI patterns MAY be ongoing state. The allowable URIs and URI patterns MAY be
restricted by the AS based on the client instance's presented key restricted by the AS based on the client instance's presented key
information. The callback URI SHOULD be presented to the RO information. The callback URI SHOULD be presented to the RO
during the interaction phase before redirect. REQUIRED for during the interaction phase before redirect. REQUIRED for
redirect and push methods. redirect and push methods.
nonce (string): Unique ASCII string value to be used in the nonce (string): Unique ASCII string value to be used in the
calculation of the "hash" query parameter sent to the callback calculation of the "hash" query parameter sent to the callback
URI, must be sufficiently random to be unguessable by an attacker. URI. It must be sufficiently random to be unguessable by an
MUST be generated by the client instance as a unique value for attacker. It MUST be generated by the client instance as a unique
this request. REQUIRED. value for this request. REQUIRED.
hash_method (string): An identifier of a hash calculation mechanism hash_method (string): An identifier of a hash calculation mechanism
to be used for the callback hash in Section 4.2.3, as defined in to be used for the callback hash in Section 4.2.3, as defined in
the IANA Named Information Hash Algorithm Registry [HASH-ALG]. If the IANA "Named Information Hash Algorithm Registry" [HASH-ALG].
absent, the default value is sha-256. OPTIONAL. If absent, the default value is sha-256. OPTIONAL.
This specification defines the following values for the method This specification defines the following values for the method
parameter, with other values defined by the GNAP Interaction Finish parameter; additional values can be defined in the "GNAP Interaction
Methods Registry (Section 11.10): Finish Methods" registry (Section 10.10):
"redirect": Indicates that the client instance can receive a "redirect": Indicates that the client instance can receive a
redirect from the end user's device after interaction with the RO redirect from the end user's device after interaction with the RO
has concluded. Section 2.5.2.1 has concluded. See Section 2.5.2.1.
"push": Indicates that the client instance can receive an HTTP POST "push": Indicates that the client instance can receive an HTTP POST
request from the AS after interaction with the RO has concluded. request from the AS after interaction with the RO has concluded.
Section 2.5.2.2 See Section 2.5.2.2.
If interaction finishing is supported for this client instance and If interaction finishing is supported for this client instance and
request, the AS will return a nonce (Section 3.3.5) used by the request, the AS will return a nonce (Section 3.3.5) used by the
client instance to validate the callback. All interaction finish client instance to validate the callback. All interaction finish
methods MUST use this nonce to allow the client to verify the methods MUST use this nonce to allow the client to verify the
connection between the pending interaction request and the callback. connection between the pending interaction request and the callback.
GNAP does this through the use of the interaction hash, defined in GNAP does this through the use of the interaction hash, defined in
Section 4.2.3. All requests to the callback URI MUST be processed as Section 4.2.3. All requests to the callback URI MUST be processed as
described in Section 4.2. described in Section 4.2.
All interaction finish methods MUST require presentation of an All interaction finish methods MUST require presentation of an
interaction reference for continuing this grant request. This means interaction reference for continuing this grant request. This means
that the interaction reference MUST be returned by the AS and MUST be that the interaction reference MUST be returned by the AS and MUST be
presented by the client as described in Section 5.1. The means by presented by the client as described in Section 5.1. The means by
which the interaction reference is returned to the client instance is which the interaction reference is returned to the client instance
specific to the interaction finish method. are specific to the interaction finish method.
2.5.2.1. Receive an HTTP Callback Through the Browser 2.5.2.1. Receive an HTTP Callback through the Browser
A finish method value of redirect indicates that the client instance A finish method value of redirect indicates that the client instance
will expect a request from the RO's browser using the HTTP method GET will expect a request from the RO's browser using the HTTP method GET
as described in Section 4.2.1. as described in Section 4.2.1.
The client instance's URI MUST be protected by HTTPS, be hosted on a The client instance's URI MUST be protected by HTTPS, be hosted on a
server local to the RO's browser ("localhost"), or use an server local to the RO's browser ("localhost"), or use an
application-specific URI scheme that is loaded on the end user's application-specific URI scheme that is loaded on the end user's
device. device.
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"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
} }
Requests to the callback URI MUST be processed by the client instance Requests to the callback URI MUST be processed by the client instance
as described in Section 4.2.1. as described in Section 4.2.1.
Since the incoming request to the callback URI is from the RO's Since the incoming request to the callback URI is from the RO's
browser, this method is usually used when the RO and end user are the browser, this method is usually used when the RO and end user are the
same entity. See Section 13.24 for considerations on ensuring the same entity. See Section 11.24 for considerations on ensuring the
incoming HTTP message matches the expected context of the request. incoming HTTP message matches the expected context of the request.
See Section 13.29 for more considerations regarding the use of front- See Section 11.29 for more considerations regarding the use of front-
channel communication techniques. channel communication techniques.
2.5.2.2. Receive an HTTP Direct Callback 2.5.2.2. Receive an HTTP Direct Callback
A finish method value of push indicates that the client instance will A finish method value of push indicates that the client instance will
expect a request from the AS directly using the HTTP method POST as expect a request from the AS directly using the HTTP method POST as
described in Section 4.2.2. described in Section 4.2.2.
The client instance's URI MUST be protected by HTTPS, be hosted on a The client instance's URI MUST be protected by HTTPS, be hosted on a
server local to the RO's browser ("localhost"), or use an server local to the RO's browser ("localhost"), or use an
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"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
} }
Requests to the callback URI MUST be processed by the client instance Requests to the callback URI MUST be processed by the client instance
as described in Section 4.2.2. as described in Section 4.2.2.
Since the incoming request to the callback URI is from the AS and not Since the incoming request to the callback URI is from the AS and not
from the RO's browser, this request is not expected to have any from the RO's browser, this request is not expected to have any
shared session information from the start method. See Section 13.24 shared session information from the start method. See Sections 11.24
and Section 13.23 for more considerations regarding the use of back- and 11.23 for more considerations regarding the use of back-channel
channel and polling mechanisms like this. and polling mechanisms like this.
2.5.3. Hints 2.5.3. Hints
The hints key is an object describing one or more suggestions from The hints key is an object describing one or more suggestions from
the client instance that the AS can use to help drive user the client instance that the AS can use to help drive user
interaction. interaction.
This specification defines the following properties under the hints This specification defines the following property under the hints
key: key:
ui_locales (array of strings): Indicates the end user's preferred ui_locales (array of strings): Indicates the end user's preferred
locales that the AS can use during interaction, particularly locales that the AS can use during interaction, particularly
before the RO has authenticated. OPTIONAL. Section 2.5.3.1 before the RO has authenticated. OPTIONAL. Section 2.5.3.1
The following sections detail requests for interaction hints. The following subsection details requests for interaction hints.
Additional interaction hints are defined in the GNAP Interaction Additional interaction hints can be defined in the "GNAP Interaction
Hints Registry (Section 11.11). Hints" registry (Section 10.11).
2.5.3.1. Indicate Desired Interaction Locales 2.5.3.1. Indicate Desired Interaction Locales
If the client instance knows the end user's locale and language If the client instance knows the end user's locale and language
preferences, the client instance can send this information to the AS preferences, the client instance can send this information to the AS
using the ui_locales field with an array of locale strings as defined using the ui_locales field with an array of locale strings as defined
by [RFC5646]. by [RFC5646].
"interact": { "interact": {
"hints": { "hints": {
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If the client instance knows the end user's locale and language If the client instance knows the end user's locale and language
preferences, the client instance can send this information to the AS preferences, the client instance can send this information to the AS
using the ui_locales field with an array of locale strings as defined using the ui_locales field with an array of locale strings as defined
by [RFC5646]. by [RFC5646].
"interact": { "interact": {
"hints": { "hints": {
"ui_locales": ["en-US", "fr-CA"] "ui_locales": ["en-US", "fr-CA"]
} }
} }
If possible, the AS SHOULD use one of the locales in the array, with If possible, the AS SHOULD use one of the locales in the array, with
preference to the first item in the array supported by the AS. If preference to the first item in the array supported by the AS. If
none of the given locales are supported, the AS MAY use a default none of the given locales are supported, the AS MAY use a default
locale. locale.
3. Grant Response 3. Grant Response
In response to a client instance's request, the AS responds with a In response to a client instance's request, the AS responds with a
JSON object as the HTTP content. Each possible field is detailed in JSON object as the HTTP content. Each possible field is detailed in
the sections below. the subsections below.
continue (object): Indicates that the client instance can continue continue (object): Indicates that the client instance can continue
the request by making one or more continuation requests. REQUIRED the request by making one or more continuation requests. REQUIRED
if continuation calls are allowed for this client instance on this if continuation calls are allowed for this client instance on this
grant request. See Section 3.1. grant request. See Section 3.1.
access_token (object / array of objects): A single access token or access_token (object / array of objects): A single access token or
set of access tokens that the client instance can use to call the set of access tokens that the client instance can use to call the
RS on behalf of the RO. REQUIRED if an access token is included. RS on behalf of the RO. REQUIRED if an access token is included.
See Section 3.2. See Section 3.2.
skipping to change at page 56, line 41 skipping to change at line 2499
Section 3.4. Section 3.4.
instance_id (string): An identifier this client instance can use to instance_id (string): An identifier this client instance can use to
identify itself when making future requests. OPTIONAL. See identify itself when making future requests. OPTIONAL. See
Section 3.5. Section 3.5.
error (object or string): An error code indicating that something error (object or string): An error code indicating that something
has gone wrong. REQUIRED for an error condition. See has gone wrong. REQUIRED for an error condition. See
Section 3.6. Section 3.6.
Additional fields can be defined by extensions to GNAP in the GNAP Additional fields can be defined by extensions to GNAP in the "GNAP
Grant Response Parameters Registry (Section 11.12). Grant Response Parameters" registry (Section 10.12).
In the following non-normative example, the AS is returning an In the following non-normative example, the AS is returning an
interaction URI (Section 3.3.1), a callback nonce (Section 3.3.5), interaction URI (Section 3.3.1), a callback nonce (Section 3.3.5),
and a continuation response (Section 3.1). and a continuation response (Section 3.1).
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
{ {
"interact": { "interact": {
"redirect": "https://server.example.com/interact/4CF492ML\ "redirect": "https://server.example.com/interact/4CF492ML\
skipping to change at page 57, line 22 skipping to change at line 2523
}, },
"continue": { "continue": {
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU", "value": "80UPRY5NM33OMUKMKSKU",
}, },
"uri": "https://server.example.com/tx" "uri": "https://server.example.com/tx"
} }
} }
In the following non-normative example, the AS is returning a bearer In the following non-normative example, the AS is returning a bearer
access token (Section 3.2.1) with a management URI and a subject access token (Section 3.2.1) with a management URI and a Subject
identifier (Section 3.4) in the form of an opaque identifier. Identifier (Section 3.4) in the form of an opaque identifier.
{ {
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"flags": ["bearer"], "flags": ["bearer"],
"manage": { "manage": {
"uri": "https://server.example.com/token/PRY5NM33O", "uri": "https://server.example.com/token/PRY5NM33O",
"access_token": { "access_token": {
"value": "B8CDFONP21-4TB8N6.BW7ONM" "value": "B8CDFONP21-4TB8N6.BW7ONM"
} }
} }
}, },
"subject": { "subject": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
} ] } ]
} }
} }
In following non-normative example, the AS is returning set of In the following non-normative example, the AS is returning set of
subject identifiers (Section 3.4), simultaneously as an opaque Subject Identifiers (Section 3.4), simultaneously as an opaque
identifier, an email address, and a decentralized identifier (DID), identifier, an email address, and a decentralized identifier (DID),
formatted as a set of Subject Identifiers defined in [RFC9493]. formatted as a set of Subject Identifiers as defined in [RFC9493].
{ {
"subject": { "subject": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
}, { }, {
"format": "email", "format": "email",
"email": "user@example.com" "email": "user@example.com"
}, { }, {
skipping to change at page 58, line 25 skipping to change at line 2570
"url": "did:example:123456" "url": "did:example:123456"
} ] } ]
} }
} }
The response MUST be sent as a JSON object in the content of the HTTP The response MUST be sent as a JSON object in the content of the HTTP
response with Content-Type application/json, unless otherwise response with Content-Type application/json, unless otherwise
specified by the specific response (e.g., an empty response with no specified by the specific response (e.g., an empty response with no
Content-Type). Content-Type).
The authorization server MUST include the HTTP Cache-Control response The AS MUST include the HTTP Cache-Control response header field
header field [RFC9111] with a value set to "no-store". [RFC9111] with a value set to "no-store".
3.1. Request Continuation 3.1. Request Continuation
If the AS determines that the grant request can be continued by the If the AS determines that the grant request can be continued by the
client instance, the AS responds with the continue field. This field client instance, the AS responds with the continue field. This field
contains a JSON object with the following properties. contains a JSON object with the following properties.
uri (string): The URI at which the client instance can make uri (string): The URI at which the client instance can make
continuation requests. This URI MAY vary per request, or MAY be continuation requests. This URI MAY vary per request or MAY be
stable at the AS. This URI MUST be an absolute URI. The client stable at the AS. This URI MUST be an absolute URI. The client
instance MUST use this value exactly as given when making a instance MUST use this value exactly as given when making a
continuation request (Section 5). REQUIRED. continuation request (Section 5). REQUIRED.
wait (integer): The amount of time in integer seconds the client wait (integer): The amount of time in integer seconds the client
instance MUST wait after receiving this request continuation instance MUST wait after receiving this request continuation
response and calling the continuation URI. The value SHOULD NOT response and calling the continuation URI. The value SHOULD NOT
be less than five seconds, and omission of the value MUST be be less than five seconds, and omission of the value MUST be
interpreted as five seconds. RECOMMENDED. interpreted as five seconds. RECOMMENDED.
access_token (object): A unique access token for continuing the access_token (object): A unique access token for continuing the
request, called the "continuation access token". The value of request, called the "continuation access token". The value of
this property MUST be an object in the format specified in this property MUST be an object in the format specified in
Section 3.2.1. This access token MUST be bound to the client Section 3.2.1. This access token MUST be bound to the client
instance's key used in the request and MUST NOT be a bearer token. instance's key used in the request and MUST NOT be a bearer token.
As a consequence, the flags array of this access token MUST NOT As a consequence, the flags array of this access token MUST NOT
contain the string bearer and the key field MUST be omitted. This contain the string bearer, and the key field MUST be omitted.
access token MUST NOT have a manage field. The client instance This access token MUST NOT have a manage field. The client
MUST present the continuation access token in all requests to the instance MUST present the continuation access token in all
continuation URI as described in Section 7.2. REQUIRED. requests to the continuation URI as described in Section 7.2.
REQUIRED.
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU" "value": "80UPRY5NM33OMUKMKSKU"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 60 "wait": 60
} }
} }
This field is REQUIRED if the grant request is in the _pending_ This field is REQUIRED if the grant request is in the _pending_
state, as the field contains the information needed by the client state, as the field contains the information needed by the client
request to continue the request as described in Section 5. Note that request to continue the request as described in Section 5. Note that
the continuation access token is bound to the client instance's key, the continuation access token is bound to the client instance's key;
and therefore the client instance MUST sign all continuation requests therefore, the client instance MUST sign all continuation requests
with its key as described in Section 7.3 and MUST present the with its key as described in Section 7.3 and MUST present the
continuation access token in its continuation request. continuation access token in its continuation request.
3.2. Access Tokens 3.2. Access Tokens
If the AS has successfully granted one or more access tokens to the If the AS has successfully granted one or more access tokens to the
client instance, the AS responds with the access_token field. This client instance, the AS responds with the access_token field. This
field contains either a single access token as described in field contains either a single access token as described in
Section 3.2.1 or an array of access tokens as described in Section 3.2.1 or an array of access tokens as described in
Section 3.2.2. Section 3.2.2.
skipping to change at page 60, line 8 skipping to change at line 2651
value (string): The value of the access token as a string. The value (string): The value of the access token as a string. The
value is opaque to the client instance. The value MUST be limited value is opaque to the client instance. The value MUST be limited
to the token68 character set defined in Section 11.2 of [HTTP] to to the token68 character set defined in Section 11.2 of [HTTP] to
facilitate transmission over HTTP headers and within other facilitate transmission over HTTP headers and within other
protocols without requiring additional encoding. REQUIRED. protocols without requiring additional encoding. REQUIRED.
label (string): The value of the label the client instance provided label (string): The value of the label the client instance provided
in the associated token request (Section 2.1), if present. in the associated token request (Section 2.1), if present.
REQUIRED for multiple access tokens or if a label was included in REQUIRED for multiple access tokens or if a label was included in
the single access token request, OPTIONAL for a single access the single access token request; OPTIONAL for a single access
token where no label was included in the request. token where no label was included in the request.
manage (object): Access information for the token management API for manage (object): Access information for the token management API for
this access token. The management URI for this access token. If this access token. If provided, the client instance MAY manage
provided, the client instance MAY manage its access token as its access token as described in Section 6. This management API
described in Section 6. This management API is a function of the is a function of the AS and is separate from the RS the client
AS and is separate from the RS the client instance is requesting instance is requesting access to. OPTIONAL.
access to. OPTIONAL.
access (array of objects/strings): A description of the rights access (array of objects/strings): A description of the rights
associated with this access token, as defined in Section 8. If associated with this access token, as defined in Section 8. If
included, this MUST reflect the rights associated with the issued included, this MUST reflect the rights associated with the issued
access token. These rights MAY vary from what was requested by access token. These rights MAY vary from what was requested by
the client instance. REQUIRED. the client instance. REQUIRED.
expires_in (integer): The number of seconds in which the access will expires_in (integer): The number of seconds in which the access will
expire. The client instance MUST NOT use the access token past expire. The client instance MUST NOT use the access token past
this time. Note that the access token MAY be revoked by the AS or this time. Note that the access token MAY be revoked by the AS or
RS at any point prior to its expiration. OPTIONAL. RS at any point prior to its expiration. OPTIONAL.
key (object / string): The key that the token is bound to, if key (object / string): The key that the token is bound to, if
different from the client instance's presented key. The key MUST different from the client instance's presented key. The key MUST
be an object or string in a format described in Section 7.1. The be an object or string in a format described in Section 7.1. The
client instance MUST be able to dereference or process the key client instance MUST be able to dereference or process the key
information in order to be able to sign subsequent requests using information in order to be able to sign subsequent requests using
the access token (Section 7.2). When the key is provided by value the access token (Section 7.2). When the key is provided by value
from the AS, the token shares some security properties with bearer from the AS, the token shares some security properties with bearer
tokens as discussed in Section 13.38. It is RECOMMENDED that keys tokens as discussed in Section 11.38. It is RECOMMENDED that keys
returned for use with access tokens be key references as described returned for use with access tokens be key references as described
in Section 7.1.1 that the client instance can correlate to its in Section 7.1.1 that the client instance can correlate to its
known keys. OPTIONAL. known keys. OPTIONAL.
flags (array of strings): A set of flags that represent attributes flags (array of strings): A set of flags that represent attributes
or behaviors of the access token issued by the AS. OPTIONAL. or behaviors of the access token issued by the AS. OPTIONAL.
The value of the manage field is an object with the following The value of the manage field is an object with the following
properties: properties:
uri (string): The URI of the token management API for this access uri (string): The URI of the token management API for this access
token. This URI MUST be an absolute URI. This URI MUST NOT include token. This URI MUST be an absolute URI. This URI MUST NOT
the access token value and SHOULD be different for each access token include the value of the access token being managed or the value
issued in a request and MUST NOT include the value of the access of the access token used to protect the URI. This URI SHOULD be
token being managed. REQUIRED. different for each access token issued in a request. REQUIRED.
access_token (object): A unique access token for continuing the access_token (object): A unique access token for continuing the
request, called the "token management access token". The value of request, called the "token management access token". The value of
this property MUST be an object in the format specified in this property MUST be an object in the format specified in
Section 3.2.1. This access token MUST be bound to the client Section 3.2.1. This access token MUST be bound to the client
instance's key used in the request (or its most recent rotation) instance's key used in the request (or its most recent rotation)
and MUST NOT be a bearer token. As a consequence, the flags array and MUST NOT be a bearer token. As a consequence, the flags array
of this access token MUST NOT contain the string bearer and the of this access token MUST NOT contain the string bearer, and the
key field MUST be omitted. This access token MUST NOT have a key field MUST be omitted. This access token MUST NOT have a
manage field. This access token MUST NOT have the same value as manage field. This access token MUST NOT have the same value as
the token it is managing. The client instance MUST present the the token it is managing. The client instance MUST present the
continuation access token in all requests to the continuation URI continuation access token in all requests to the continuation URI
as described in Section 7.2. REQUIRED. as described in Section 7.2. REQUIRED.
The values of the flags field defined by this specification are as The values of the flags field defined by this specification are as
follows: follows:
"bearer": This flag indicates whether the token is a bearer token, "bearer": Flag indicating whether the token is a bearer token, not
not bound to a key and proofing mechanism. If the bearer flag is bound to a key and proofing mechanism. If the bearer flag is
present, the access token is a bearer token, and the key field in present, the access token is a bearer token, and the key field in
this response MUST be omitted. See Section 13.9 for additional this response MUST be omitted. See Section 11.9 for additional
considerations on the use of bearer tokens. considerations on the use of bearer tokens.
"durable": Flag indicating a hint of AS behavior on token rotation. "durable": Flag indicating a hint of AS behavior on token rotation.
If this flag is present, then the client instance can expect a If this flag is present, then the client instance can expect a
previously-issued access token to continue to work after it has previously issued access token to continue to work after it has
been rotated (Section 6.1) or the underlying grant request has been rotated (Section 6.1) or the underlying grant request has
been modified (Section 5.3), resulting in the issuance of new been modified (Section 5.3), resulting in the issuance of new
access tokens. If this flag is omitted, the client instance can access tokens. If this flag is omitted, the client instance can
anticipate a given access token could stop working after token anticipate a given access token could stop working after token
rotation or grant request modification. Note that a token flagged rotation or grant request modification. Note that a token flagged
as durable can still expire or be revoked through any normal as durable can still expire or be revoked through any normal
means. means.
Flag values MUST NOT be included more than once. Flag values MUST NOT be included more than once.
Additional flags can be defined by extensions using the GNAP Access Additional flags can be defined by extensions using the "GNAP Access
Token Fields Registry (Section 11.4). Token Flags" registry (Section 10.4).
If the bearer flag and the key field in this response are omitted, If the bearer flag and the key field in this response are omitted,
the token is bound the key used by the client instance (Section 2.3) the token is bound to the key used by the client instance
in its request for access. If the bearer flag is omitted, and the (Section 2.3) in its request for access. If the bearer flag is
key field is present, the token is bound to the key and proofing omitted and the key field is present, the token is bound to the key
mechanism indicated in the key field. The means by which the AS and proofing mechanism indicated in the key field. The means by
determines how to bind an access token to a key other than that which the AS determines how to bind an access token to a key other
presented by the client instance is out of scope for this than that presented by the client instance are out of scope for this
specification, but common practices include pre-registering specific specification, but common practices include pre-registering specific
keys in a static fashion. keys in a static fashion.
The client software MUST reject any access token where the flags The client software MUST reject any access token where the flags
field contains the bearer flag and the key field is present with any field contains the bearer flag and the key field is present with any
value. value.
The following non-normative example shows a single access token bound The following non-normative example shows a single access token bound
to the client instance's key used in the initial request, with a to the client instance's key used in the initial request. The access
management URI, and that has access to three described resources (one token has a management URI and has access to three described
using an object and two described by reference strings). resources (one using an object and two described by reference
strings).
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"manage": { "manage": {
"uri": "https://server.example.com/token/PRY5NM33O", "uri": "https://server.example.com/token/PRY5NM33O",
"access_token": { "access_token": {
"value": "B8CDFONP21-4TB8N6.BW7ONM" "value": "B8CDFONP21-4TB8N6.BW7ONM"
} }
skipping to change at page 63, line 14 skipping to change at line 2796
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"flags": ["bearer"], "flags": ["bearer"],
"access": [ "access": [
"finance", "medical" "finance", "medical"
] ]
} }
If the client instance requested a single access token If the client instance requested a single access token
(Section 2.1.1), the AS MUST NOT respond with the multiple access (Section 2.1.1), the AS MUST NOT respond with the structure for
token structure. multiple access tokens.
3.2.2. Multiple Access Tokens 3.2.2. Multiple Access Tokens
If the client instance has requested multiple access tokens and the If the client instance has requested multiple access tokens and the
AS has granted at least one of them, the AS responds with the AS has granted at least one of them, the AS responds with the
"access_token" field. The value of this field is a JSON array, the "access_token" field. The value of this field is a JSON array, the
members of which are distinct access tokens as described in members of which are distinct access tokens as described in
Section 3.2.1. Each object MUST have a unique label field, Section 3.2.1. Each object MUST have a unique label field,
corresponding to the token labels chosen by the client instance in corresponding to the token labels chosen by the client instance in
the multiple access token request (Section 2.1.2). the request for multiple access tokens (Section 2.1.2).
In the following non-normative example, two tokens are issued under In the following non-normative example, two tokens are issued under
the names token1 and token2, and only the first token has a the names token1 and token2, and only the first token has a
management URI associated with it. management URI associated with it.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
"access_token": [ "access_token": [
{ {
"label": "token1", "label": "token1",
skipping to change at page 64, line 4 skipping to change at line 2833
} }
}, },
"access": [ "finance" ] "access": [ "finance" ]
}, },
{ {
"label": "token2", "label": "token2",
"value": "UFGLO2FDAFG7VGZZPJ3IZEMN21EVU71FHCARP4J1", "value": "UFGLO2FDAFG7VGZZPJ3IZEMN21EVU71FHCARP4J1",
"access": [ "medical" ] "access": [ "medical" ]
} }
} }
Each access token corresponds to one of the objects in the Each access token corresponds to one of the objects in the
access_token array of the client instance's request (Section 2.1.2). access_token array of the client instance's request (Section 2.1.2).
The AS MAY refuse to issue one or more of the requested access The AS MAY refuse to issue one or more of the requested access tokens
tokens, for any reason. In such cases the refused token is omitted for any reason. In such cases, the refused token is omitted from the
from the response and all of the other issued access tokens are response, and all of the other issued access tokens are included in
included in the response under their respective requested labels. If the response under their respective requested labels. If the client
the client instance requested multiple access tokens (Section 2.1.2), instance requested multiple access tokens (Section 2.1.2), the AS
the AS MUST NOT respond with a single access token structure, even if MUST NOT respond with a single access token structure, even if only a
only a single access token is granted. In such cases, the AS MUST single access token is granted. In such cases, the AS MUST respond
respond with a multiple access token structure containing one access with a structure for multiple access tokens containing one access
token. token.
"access_token": [ "access_token": [
{ {
"label": "token2", "label": "token2",
"value": "8N6BW7OZB8CDFONP219-OS9M2PMHKUR64TBRP1LT0", "value": "8N6BW7OZB8CDFONP219-OS9M2PMHKUR64TBRP1LT0",
"manage": { "manage": {
"uri": "https://server.example.com/token/PRY5NM33O", "uri": "https://server.example.com/token/PRY5NM33O",
"access_token": { "access_token": {
"value": "B8CDFONP21-4TB8N6.BW7ONM" "value": "B8CDFONP21-4TB8N6.BW7ONM"
} }
}, },
"access": [ "fruits" ] "access": [ "fruits" ]
} }
] ]
The parameters of each access token are separate. For example, each The parameters of each access token are separate. For example, each
access token is expected to have a unique value and (if present) access token is expected to have a unique value and (if present)
label, and likely has different access rights associated with it. label, and each access token likely has different access rights
Each access token could also be bound to different keys with associated with it. Each access token could also be bound to
different proofing mechanisms. different keys with different proofing mechanisms.
3.3. Interaction Modes 3.3. Interaction Modes
If the client instance has indicated a capability to interact with If the client instance has indicated a capability to interact with
the RO in its request (Section 2.5), and the AS has determined that the RO in its request (Section 2.5) and the AS has determined that
interaction is both supported and necessary, the AS responds to the interaction is both supported and necessary, the AS responds to the
client instance with any of the following values in the interact client instance with any of the following values in the interact
field of the response. There is no preference order for interaction field of the response. There is no preference order for interaction
modes in the response, and it is up to the client instance to modes in the response, and it is up to the client instance to
determine which ones to use. All supported interaction methods are determine which ones to use. All supported interaction methods are
included in the same interact object. included in the same interact object.
redirect (string): Redirect to an arbitrary URI. REQUIRED if the redirect (string): Redirect to an arbitrary URI. REQUIRED if the
redirect interaction start mode is possible for this request. See redirect interaction start mode is possible for this request. See
Section 3.3.1. Section 3.3.1.
skipping to change at page 65, line 26 skipping to change at line 2903
finish (string): A unique ASCII string value provided by the AS as a finish (string): A unique ASCII string value provided by the AS as a
nonce. This is used by the client instance to verify the callback nonce. This is used by the client instance to verify the callback
after interaction is completed. REQUIRED if the interaction after interaction is completed. REQUIRED if the interaction
finish method requested by the client instance is possible for finish method requested by the client instance is possible for
this request. See Section 3.3.5. this request. See Section 3.3.5.
expires_in (integer): The number of integer seconds after which this expires_in (integer): The number of integer seconds after which this
set of interaction responses will expire and no longer be usable set of interaction responses will expire and no longer be usable
by the client instance. If the interaction methods expire, the by the client instance. If the interaction methods expire, the
client MAY re-start the interaction process for this grant request client MAY restart the interaction process for this grant request
by sending an update (Section 5.3) with a new interaction request by sending an update (Section 5.3) with a new interaction request
(Section 2.5) section. OPTIONAL. If omitted, the interaction field (Section 2.5). OPTIONAL. If omitted, the interaction
response modes returned do not expire but MAY be invalidated by response modes returned do not expire but MAY be invalidated by
the AS at any time. the AS at any time.
Additional interaction mode responses can be defined in the GNAP Additional interaction mode responses can be defined in the "GNAP
Interaction Mode Responses Registry (Section 11.13). Interaction Mode Responses" registry (Section 10.13).
The AS MUST NOT respond with any interaction mode that the client The AS MUST NOT respond with any interaction mode that the client
instance did not indicate in its request. The AS MUST NOT respond instance did not indicate in its request, and the AS MUST NOT respond
with any interaction mode that the AS does not support. Since with any interaction mode that the AS does not support. Since
interaction responses include secret or unique information, the AS interaction responses include secret or unique information, the AS
SHOULD respond to each interaction mode only once in an ongoing SHOULD respond to each interaction mode only once in an ongoing
request, particularly if the client instance modifies its request request, particularly if the client instance modifies its request
(Section 5.3). (Section 5.3).
The grant request MUST be in the _pending_ state to include this The grant request MUST be in the _pending_ state to include this
field in the response. field in the response.
3.3.1. Redirection to an arbitrary URI 3.3.1. Redirection to an Arbitrary URI
If the client instance indicates that it can redirect to an arbitrary If the client instance indicates that it can redirect to an arbitrary
URI (Section 2.5.1.1) and the AS supports this mode for the client URI (Section 2.5.1.1) and the AS supports this mode for the client
instance's request, the AS responds with the "redirect" field, which instance's request, the AS responds with the "redirect" field, which
is a string containing the URI for the end user to visit. This URI is a string containing the URI for the end user to visit. This URI
MUST be unique for the request and MUST NOT contain any security- MUST be unique for the request and MUST NOT contain any security-
sensitive information such as user identifiers or access tokens. sensitive information such as user identifiers or access tokens.
"interact": { "interact": {
"redirect": "https://interact.example.com/4CF492MLVMSW9MKMXKHQ" "redirect": "https://interact.example.com/4CF492MLVMSW9MKMXKHQ"
} }
The URI returned is a function of the AS, but the URI itself MAY be The URI returned is a function of the AS, but the URI itself MAY be
completely distinct from the grant endpoint URI that the client completely distinct from the grant endpoint URI that the client
instance uses to request access (Section 2), allowing an AS to instance uses to request access (Section 2), allowing an AS to
separate its user-interactive functionality from its back-end separate its user-interaction functionality from its backend security
security functionality. The AS will need to dereference the specific functionality. The AS will need to dereference the specific grant
grant request and its information from the URI alone. If the AS does request and its information from the URI alone. If the AS does not
not directly host the functionality accessed through the redirect directly host the functionality accessed through the redirect URI,
URI, then the means for the interaction functionality to communicate then the means for the interaction functionality to communicate with
with the rest of the AS are out of scope for this specification. the rest of the AS are out of scope for this specification.
The client instance sends the end user to the URI to interact with The client instance sends the end user to the URI to interact with
the AS. The client instance MUST NOT alter the URI in any way. The the AS. The client instance MUST NOT alter the URI in any way. The
means for the client instance to send the end user to this URI is out means for the client instance to send the end user to this URI are
of scope of this specification, but common methods include an HTTP out of scope of this specification, but common methods include an
redirect, launching the system browser, displaying a scannable code, HTTP redirect, launching the system browser, displaying a scannable
or printing out the URI in an interactive console. See details of code, or printing out the URI in an interactive console. See details
the interaction in Section 4.1.1. of the interaction in Section 4.1.1.
3.3.2. Launch of an application URI 3.3.2. Launch of an Application URI
If the client instance indicates that it can launch an application If the client instance indicates that it can launch an application
URI (Section 2.5.1.2) and the AS supports this mode for the client URI (Section 2.5.1.2) and the AS supports this mode for the client
instance's request, the AS responds with the "app" field, which is a instance's request, the AS responds with the "app" field, which is a
string containing the URI for the client instance to launch. This string containing the URI for the client instance to launch. This
URI MUST be unique for the request and MUST NOT contain any security- URI MUST be unique for the request and MUST NOT contain any security-
sensitive information such as user identifiers or access tokens. sensitive information such as user identifiers or access tokens.
"interact": { "interact": {
"app": "https://app.example.com/launch?tx=4CF492MLV" "app": "https://app.example.com/launch?tx=4CF492MLV"
} }
The means for the launched application to communicate with the AS are The means for the launched application to communicate with the AS are
out of scope for this specification. out of scope for this specification.
The client instance launches the URI as appropriate on its platform, The client instance launches the URI as appropriate on its platform;
and the means for the client instance to launch this URI is out of the means for the client instance to launch this URI are out of scope
scope of this specification. The client instance MUST NOT alter the of this specification. The client instance MUST NOT alter the URI in
URI in any way. The client instance MAY attempt to detect if an any way. The client instance MAY attempt to detect if an installed
installed application will service the URI being sent before application will service the URI being sent before attempting to
attempting to launch the application URI. See details of the launch the application URI. See details of the interaction in
interaction in Section 4.1.4. Section 4.1.4.
3.3.3. Display of a Short User Code 3.3.3. Display of a Short User Code
If the client instance indicates that it can display a short If the client instance indicates that it can display a short, user-
user-typeable code (Section 2.5.1.3) and the AS supports this mode typeable code (Section 2.5.1.3) and the AS supports this mode for the
for the client instance's request, the AS responds with a "user_code" client instance's request, the AS responds with a "user_code" field.
field. This field is string containing a unique short code that the This field is string containing a unique short code that the user can
user can type into a web page. To facilitate usability, this string type into a web page. To facilitate usability, this string MUST
MUST consist only of characters that can be easily typed by the end consist only of characters that can be easily typed by the end user
user (such as ASCII letters or numbers) and MUST be processed by the (such as ASCII letters or numbers) and MUST be processed by the AS in
AS in a case-insensitive manner (see Section 4.1.2). The string MUST a case-insensitive manner (see Section 4.1.2). The string MUST be
be randomly generated so as to be unguessable by an attacker within randomly generated so as to be unguessable by an attacker within the
the time it is accepted. The time in which this code will be time it is accepted. The time in which this code will be accepted
accepted SHOULD be short lived, such as several minutes. It is SHOULD be short lived, such as several minutes. It is RECOMMENDED
RECOMMENDED that this code be no more than eight characters in that this code be between six and eight characters in length.
length.
"interact": { "interact": {
"user_code": "A1BC3DFF" "user_code": "A1BC3DFF"
} }
The client instance MUST communicate the "user_code" value to the end The client instance MUST communicate the "user_code" value to the end
user in some fashion, such as displaying it on a screen or reading it user in some fashion, such as displaying it on a screen or reading it
out audibly. This code is used by the interaction component of the out audibly. This code is used by the interaction component of the
AS as a means of identifying the pending grant request and does not AS as a means of identifying the pending grant request and does not
function as an authentication factor for the RO. function as an authentication factor for the RO.
The URI that the end user is intended to enter the code into MUST be The URI that the end user is intended to enter the code into MUST be
stable, since the client instance is expected to have no means of stable, since the client instance is expected to have no means of
communicating a dynamic URI to the end user at runtime. communicating a dynamic URI to the end user at runtime.
As this interaction mode is designed to facilitate interaction via a As this interaction mode is designed to facilitate interaction via a
secondary device, it is not expected that the client instance secondary device, it is not expected that the client instance
redirect the end user to the URI where the code is entered. If the redirect the end user to the URI where the code is entered. If the
client instance is capable of communicating an short arbitrary URI to client instance is capable of communicating a short arbitrary URI to
the end user for use with the user code, the client instance SHOULD the end user for use with the user code, the client instance SHOULD
instead use the "user_code_uri" (Section 2.5.1.4) mode. If the instead use the "user_code_uri" mode (Section 2.5.1.4). If the
client instance is capable of communicating a long arbitrary URI to client instance is capable of communicating a long arbitrary URI to
the end user, such as through a scannable code, the client instance the end user, such as through a scannable code, the client instance
SHOULD use the "redirect" (Section 2.5.1.1) mode for this purpose SHOULD use the "redirect" mode (Section 2.5.1.1) for this purpose,
instead of or in addition to the user code mode. instead of or in addition to the user code mode.
See details of the interaction in Section 4.1.2. See details of the interaction in Section 4.1.2.
3.3.4. Display of a Short User Code and URI 3.3.4. Display of a Short User Code and URI
If the client instance indicates that it can display a short If the client instance indicates that it can display a short, user-
user-typeable code (Section 2.5.1.3) and the AS supports this mode typeable code (Section 2.5.1.3) and the AS supports this mode for the
for the client instance's request, the AS responds with a client instance's request, the AS responds with a "user_code_uri"
"user_code_uri" object that contains the following members. object that contains the following members.
code (string): A unique short code that the end user can type into a code (string): A unique short code that the end user can type into a
provided URI. To facilitate usability, this string MUST consist provided URI. To facilitate usability, this string MUST consist
only of characters that can be easily typed by the end user (such only of characters that can be easily typed by the end user (such
as ASCII letters or numbers) and MUST be processed by the AS in a as ASCII letters or numbers) and MUST be processed by the AS in a
case-insensitive manner (see Section 4.1.3). The string MUST be case-insensitive manner (see Section 4.1.3). The string MUST be
randomly generated so as to be unguessable by an attacker within randomly generated so as to be unguessable by an attacker within
the time it is accepted. The time in which this code will be the time it is accepted. The time in which this code will be
accepted SHOULD be short lived, such as several minutes. It is accepted SHOULD be short lived, such as several minutes. It is
RECOMMENDED that this code be no more than eight characters in RECOMMENDED that this code be between six and eight characters in
length. REQUIRED. length. REQUIRED.
uri (string): The interaction URI that the client instance will uri (string): The interaction URI that the client instance will
direct the RO to. This URI MUST be short enough to be direct the RO to. This URI MUST be short enough to be
communicated to the end user by the client instance. It is communicated to the end user by the client instance. It is
RECOMMENDED that this URI be short enough for an end user to type RECOMMENDED that this URI be short enough for an end user to type
in manually. The URI MUST NOT contain the code value. This URI in manually. The URI MUST NOT contain the code value. This URI
MUST be an absolute URI. REQUIRED. MUST be an absolute URI. REQUIRED.
"interact": { "interact": {
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function as an authentication factor for the RO. function as an authentication factor for the RO.
The client instance MUST also communicate the URI to the end user. The client instance MUST also communicate the URI to the end user.
Since it is expected that the end user will continue interaction on a Since it is expected that the end user will continue interaction on a
secondary device, the URI needs to be short enough to allow the end secondary device, the URI needs to be short enough to allow the end
user to type or copy it to a secondary device without mistakes. user to type or copy it to a secondary device without mistakes.
The URI returned is a function of the AS, but the URI itself MAY be The URI returned is a function of the AS, but the URI itself MAY be
completely distinct from the grant endpoint URI that the client completely distinct from the grant endpoint URI that the client
instance uses to request access (Section 2), allowing an AS to instance uses to request access (Section 2), allowing an AS to
separate its user-interactive functionality from its back-end separate its user-interaction functionality from its backend security
security functionality. If the AS does not directly host the functionality. If the AS does not directly host the functionality
functionality accessed through the given URI, then the means for the accessed through the given URI, then the means for the interaction
interaction functionality to communicate with the rest of the AS are functionality to communicate with the rest of the AS are out of scope
out of scope for this specification. for this specification.
See details of the interaction in Section 4.1.2. See details of the interaction in Section 4.1.2.
3.3.5. Interaction Finish 3.3.5. Interaction Finish
If the client instance indicates that it can receive a If the client instance indicates that it can receive a post-
post-interaction redirect or push at a URI (Section 2.5.2) and the AS interaction redirect or push at a URI (Section 2.5.2) and the AS
supports this mode for the client instance's request, the AS responds supports this mode for the client instance's request, the AS responds
with a finish field containing a nonce that the client instance will with a finish field containing a nonce that the client instance will
use in validating the callback as defined in Section 4.2. use in validating the callback as defined in Section 4.2.
"interact": { "interact": {
"finish": "MBDOFXG4Y5CVJCX821LH" "finish": "MBDOFXG4Y5CVJCX821LH"
} }
When the interaction is completed, the interaction component of the When the interaction is completed, the interaction component of the
AS MUST contact the client instance using the means defined by the AS MUST contact the client instance using the means defined by the
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If information about the RO is requested and the AS grants the client If information about the RO is requested and the AS grants the client
instance access to that data, the AS returns the approved information instance access to that data, the AS returns the approved information
in the "subject" response field. The AS MUST return the subject in the "subject" response field. The AS MUST return the subject
field only in cases where the AS is sure that the RO and the end user field only in cases where the AS is sure that the RO and the end user
are the same party. This can be accomplished through some forms of are the same party. This can be accomplished through some forms of
interaction with the RO (Section 4). interaction with the RO (Section 4).
This field is an object with the following properties. This field is an object with the following properties.
sub_ids (array of objects): An array of subject identifiers for the sub_ids (array of objects): An array of Subject Identifiers for the
RO, as defined by [RFC9493]. REQUIRED if returning subject RO, as defined by [RFC9493]. REQUIRED if returning Subject
identifiers. Identifiers.
assertions (array of objects): An array containing assertions as assertions (array of objects): An array containing assertions as
objects each containing the assertion object described below. objects, each containing the assertion object described below.
REQUIRED if returning assertions. REQUIRED if returning assertions.
updated_at (string): Timestamp as an [RFC3339] date string, updated_at (string): Timestamp as a date string as described in
indicating when the identified account was last updated. The [RFC3339], indicating when the identified account was last
client instance MAY use this value to determine if it needs to updated. The client instance MAY use this value to determine if
request updated profile information through an identity API. The it needs to request updated profile information through an
definition of such an identity API is out of scope for this identity API. The definition of such an identity API is out of
specification. RECOMMENDED. scope for this specification. RECOMMENDED.
Assertion objects contain the following fields: Assertion objects contain the following fields:
format (string): The assertion format. Possible formats are listed format (string): The assertion format. Possible formats are listed
in Section 3.4.1. Additional assertion formats are defined by the in Section 3.4.1. Additional assertion formats can be defined in
GNAP Assertion Formats Registry (Section 11.6). REQUIRED. the "GNAP Assertion Formats" registry (Section 10.6). REQUIRED.
value (string): The assertion value as the JSON string serialization value (string): The assertion value as the JSON string serialization
of the assertion. REQUIRED. of the assertion. REQUIRED.
The following non-normative example contains an opaque identifier and The following non-normative example contains an opaque identifier and
an OpenID Connect ID Token: an OpenID Connect ID Token:
"subject": { "subject": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "XUT2MFM1XBIKJKSDU8QM" "id": "XUT2MFM1XBIKJKSDU8QM"
} ], } ],
"assertions": [ { "assertions": [ {
"format": "id_token", "format": "id_token",
"value": "eyj..." "value": "eyj..."
} ] } ]
} }
Subject identifiers returned by the AS SHOULD uniquely identify the Subject Identifiers returned by the AS SHOULD uniquely identify the
RO at the AS. Some forms of subject identifier are opaque to the RO at the AS. Some forms of Subject Identifiers are opaque to the
client instance (such as the subject of an issuer and subject pair), client instance (such as the subject of an issuer and subject pair),
while others forms (such as email address and phone number) are while other forms (such as email address and phone number) are
intended to allow the client instance to correlate the identifier intended to allow the client instance to correlate the identifier
with other account information at the client instance. The client with other account information at the client instance. The client
instance MUST NOT request or use any returned subject identifiers for instance MUST NOT request or use any returned Subject Identifiers for
communication purposes (see Section 2.2). That is, a subject communication purposes (see Section 2.2). That is, a Subject
identifier returned in the format of an email address or a phone Identifier returned in the format of an email address or a phone
number only identifies the RO to the AS and does not indicate that number only identifies the RO to the AS and does not indicate that
the AS has validated that the represented email address or phone the AS has validated that the represented email address or phone
number in the identifier is suitable for communication with the number in the identifier is suitable for communication with the
current user. To get such information, the client instance MUST use current user. To get such information, the client instance MUST use
an identity protocol to request and receive additional identity an identity protocol to request and receive additional identity
claims. The details of an identity protocol and associated schema claims. The details of an identity protocol and associated schema
are outside the scope of this specification. are outside the scope of this specification.
The AS MUST ensure that the returned subject information represents The AS MUST ensure that the returned subject information represents
the RO. In most cases, the AS will also ensure that the returned the RO. In most cases, the AS will also ensure that the returned
subject information represents the end user authenticated subject information represents the end user authenticated
interactively at the AS. The AS SHOULD NOT re-use subject interactively at the AS. The AS SHOULD NOT reuse Subject Identifiers
identifiers for multiple different ROs. for multiple different ROs.
The "sub_ids" and "assertions" response fields are independent of The "sub_ids" and "assertions" response fields are independent of
each other. That is, a returned assertion MAY use a different each other. That is, a returned assertion MAY use a different
subject identifier than other assertions and subject identifiers in Subject Identifier than other assertions and Subject Identifiers in
the response. However, all subject identifiers and assertions the response. However, all Subject Identifiers and assertions
returned MUST refer to the same party. returned MUST refer to the same party.
The client instance MUST interpret all subject information in the The client instance MUST interpret all subject information in the
context of the AS from which the subject information is received, as context of the AS from which the subject information is received, as
is discussed in Section 6 of [SP80063C]. For example, one AS could is discussed in Section 6 of [SP80063C]. For example, one AS could
return an email identifier of "user@example.com" for one RO, and a return an email identifier of "user@example.com" for one RO, and a
different AS could return that same email identifier of different AS could return that same email identifier of
"user@example.com" for a completely different RO. A client instance "user@example.com" for a completely different RO. A client instance
talking to both AS's needs to differentiate between these two talking to both ASes needs to differentiate between these two
accounts by accounting for the AS source of each identifier and not accounts by accounting for the AS source of each identifier and not
assuming that either has a canonical claim on the identifier without assuming that either has a canonical claim on the identifier without
additional configuration and trust agreements. Otherwise, a rogue AS additional configuration and trust agreements. Otherwise, a rogue AS
could exploit this to take over a targeted account asserted by a could exploit this to take over a targeted account asserted by a
different AS. different AS.
Extensions to this specification MAY define additional response Extensions to this specification MAY define additional response
properties in the GNAP Subject Information Response Fields Registry properties in the "GNAP Subject Information Response Fields" registry
(Section 11.14). (Section 10.14).
The grant request MUST be in the _approved_ state to return this The grant request MUST be in the _approved_ state to return this
field in the response. field in the response.
See Section 13.30 for considerations that the client instance has to See Section 11.30 for considerations that the client instance has to
make when accepting and processing assertions from the AS. make when accepting and processing assertions from the AS.
3.4.1. Assertion Formats 3.4.1. Assertion Formats
The following assertion formats are defined in this specification: The following assertion formats are defined in this specification:
id_token: An OpenID Connect ID Token ([OIDC]), in JWT compact format id_token: An OpenID Connect ID Token [OIDC], in JSON Web Token (JWT)
as a single string. compact format as a single string.
saml2: A SAML 2 assertion ([SAML2]), encoded as a single base64url saml2: A SAML 2.0 assertion [SAML2], encoded as a single base64url
string with no padding. string with no padding.
3.5. Returning a Dynamically-bound Client Instance Identifier 3.5. Returning a Dynamically Bound Client Instance Identifier
Many parts of the client instance's request can be passed as either a Many parts of the client instance's request can be passed as either a
value or a reference. The use of a reference in place of a value value or a reference. The use of a reference in place of a value
allows for a client instance to optimize requests to the AS. allows for a client instance to optimize requests to the AS.
Some references, such as for the client instance's identity Some references, such as for the client instance's identity
(Section 2.3.1) or the requested resources (Section 8.1), can be (Section 2.3.1) or the requested resources (Section 8.1), can be
managed statically through an admin console or developer portal managed statically through an admin console or developer portal
provided by the AS or RS. The developer of the client software can provided by the AS or RS. The developer of the client software can
include these values in their code for a more efficient and compact include these values in their code for a more efficient and compact
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information that would compromise any party if revealed. Instance information that would compromise any party if revealed. Instance
identifier values are opaque to the client instance, and their identifier values are opaque to the client instance, and their
content is determined by the AS. The instance identifier MUST be content is determined by the AS. The instance identifier MUST be
unique per client instance at the AS. unique per client instance at the AS.
instance_id (string): A string value used to represent the instance_id (string): A string value used to represent the
information in the client object that the client instance can use information in the client object that the client instance can use
in a future request, as described in Section 2.3.1. OPTIONAL. in a future request, as described in Section 2.3.1. OPTIONAL.
The following non-normative example shows an instance identifier The following non-normative example shows an instance identifier
along side an issued access token. alongside an issued access token.
{ {
"instance_id": "7C7C4AZ9KHRS6X63AJAO", "instance_id": "7C7C4AZ9KHRS6X63AJAO",
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0" "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0"
} }
} }
3.6. Error Response 3.6. Error Response
If the AS determines that the request cannot be completed for any If the AS determines that the request cannot be completed for any
reason, it responds to the client instance with an error field in the reason, it responds to the client instance with an error field in the
response message. This field is either an object or a string. response message. This field is either an object or a string.
When returned as an object, the object contains the following fields: When returned as an object, the object contains the following fields:
code (string): A single ASCII error code defining the error. The code (string): A single ASCII error code defining the error. The
value MUST be defined in the GNAP Error Codes Registry value MUST be defined in the "GNAP Error Codes" registry
(Section 11.15). REQUIRED. (Section 10.15). REQUIRED.
description (string): A human-readable string description of the description (string): A human-readable string description of the
error intended for the developer of the client. The value is error intended for the developer of the client. The value is
chosen by the implementation. OPTIONAL. chosen by the implementation. OPTIONAL.
This specification defines the following code values: This specification defines the following code values:
"invalid_request": The request is missing a required parameter, "invalid_request": The request is missing a required parameter,
includes an invalid parameter value or is otherwise malformed. includes an invalid parameter value, or is otherwise malformed.
"invalid_client": The request was made from a client that was not "invalid_client": The request was made from a client that was not
recognized or allowed by the AS, or the client's signature recognized or allowed by the AS, or the client's signature
validation failed. validation failed.
"invalid_interaction" The client instance has provided an "invalid_interaction": The client instance has provided an
interaction reference that is incorrect for this request or the interaction reference that is incorrect for this request, or the
interaction modes in use have expired. interaction modes in use have expired.
"invalid_flag" The flag configuration is not valid. "invalid_flag": The flag configuration is not valid.
"invalid_rotation" The token rotation request is not valid. "invalid_rotation": The token rotation request is not valid.
"key_rotation_not_supported" The AS does not allow rotation of this "key_rotation_not_supported": The AS does not allow rotation of this
access token's key. access token's key.
"invalid_continuation": The continuation of the referenced grant "invalid_continuation": The continuation of the referenced grant
could not be processed. could not be processed.
"user_denied": The RO denied the request. "user_denied": The RO denied the request.
"request_denied": The request was denied for an unspecified reason. "request_denied": The request was denied for an unspecified reason.
"unknown_user": The user presented in the request is not known to "unknown_user": The user presented in the request is not known to
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"unknown_interaction": The interaction integrity could not be "unknown_interaction": The interaction integrity could not be
established. established.
"too_fast": The client instance did not respect the timeout in the "too_fast": The client instance did not respect the timeout in the
wait response before the next call. wait response before the next call.
"too_many_attempts": A limit has been reached in the total number of "too_many_attempts": A limit has been reached in the total number of
reasonable attempts. This number is either defined statically or reasonable attempts. This number is either defined statically or
adjusted based on runtime conditions by the AS. adjusted based on runtime conditions by the AS.
Additional error codes can be defined in the GNAP Error Codes Additional error codes can be defined in the "GNAP Error Codes"
Registry (Section 11.15). registry (Section 10.15).
For example, if the RO denied the request while interacting with the For example, if the RO denied the request while interacting with the
AS, the AS would return the following error when the client instance AS, the AS would return the following error when the client instance
tries to continue the grant request: tries to continue the grant request:
{ {
"error": { "error": {
"code": "user_denied", "code": "user_denied",
"description": "The RO denied the request" "description": "The RO denied the request"
} }
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considered functionally equivalent to the previous example for the considered functionally equivalent to the previous example for the
purposes of the client software's understanding: purposes of the client software's understanding:
{ {
"error": "user_denied" "error": "user_denied"
} }
If an error state is reached but the grant is in the _pending_ state If an error state is reached but the grant is in the _pending_ state
(and therefore the client instance can continue), the AS MAY include (and therefore the client instance can continue), the AS MAY include
the continue field in the response along with the error, as defined the continue field in the response along with the error, as defined
Section 3.1. This allows the client instance to modify its request in Section 3.1. This allows the client instance to modify its
for access, potentially leading to prompting the RO again. Other request for access, potentially leading to prompting the RO again.
fields MUST NOT be included in the response. Other fields MUST NOT be included in the response.
4. Determining Authorization and Consent 4. Determining Authorization and Consent
When the client instance makes its initial request (Section 2) to the When the client instance makes its initial request (Section 2) to the
AS for delegated access, it is capable of asking for several AS for delegated access, it is capable of asking for several
different kinds of information in response: different kinds of information in response:
* the access being requested, in the access_token request parameter * the access being requested, in the access_token request parameter
* the subject information being requested, in the subject request * the subject information being requested, in the subject request
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When the grant request is in the _processing_ state, the AS When the grant request is in the _processing_ state, the AS
determines what authorizations and consents are required to fulfill determines what authorizations and consents are required to fulfill
this requested delegation. The details of how the AS makes this this requested delegation. The details of how the AS makes this
determination are out of scope for this document. However, there are determination are out of scope for this document. However, there are
several common patterns defined and supported by GNAP for fulfilling several common patterns defined and supported by GNAP for fulfilling
these requirements, including information sent by the client these requirements, including information sent by the client
instance, information gathered through the interaction process, and instance, information gathered through the interaction process, and
information supplied by external parties. An individual AS can information supplied by external parties. An individual AS can
define its own policies and processes for deciding when and how to define its own policies and processes for deciding when and how to
gather the necessary authorizations and consent, and how those are gather the necessary authorizations and consent and how those are
applied to the grant request. applied to the grant request.
To facilitate the AS fulfilling this request, the client instance To facilitate the AS fulfilling this request, the client instance
sends information about the actions the client software can take, sends information about the actions the client software can take,
including: including:
* starting interaction with the end user, in the interact request * starting interaction with the end user, in the interact request
parameter parameter
* receiving notification that interaction with the RO has concluded, * receiving notification that interaction with the RO has concluded,
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determines that the information presented in the initial request is determines that the information presented in the initial request is
sufficient for granting the requested access, the AS MAY move the sufficient for granting the requested access, the AS MAY move the
grant request to the _approved_ state and return results immediately grant request to the _approved_ state and return results immediately
in its response (Section 3) with access tokens and subject in its response (Section 3) with access tokens and subject
information. information.
If the AS determines that additional runtime authorization is If the AS determines that additional runtime authorization is
required, the AS can either deny the request outright (if there is no required, the AS can either deny the request outright (if there is no
possible recovery) or move the grant request to the _pending_ state possible recovery) or move the grant request to the _pending_ state
and use a number of means at its disposal to gather that and use a number of means at its disposal to gather that
authorization from the appropriate ROs, including for example: authorization from the appropriate ROs, including:
* starting interaction with the end user facilitated by the client * starting interaction with the end user facilitated by the client
software, such as a redirection or user code software, such as a redirection or user code
* challenging the client instance through a challenge-response * challenging the client instance through a challenge-response
mechanism mechanism
* requesting that the client instance present specific additional * requesting that the client instance present specific additional
information, such as a user's credential or an assertion information, such as a user's credential or an assertion
* contacting an RO through an out-of-band mechanism, such as a push * contacting an RO through an out-of-band mechanism, such as a push
notification notification
* executing an auxiliary software process through an out-of-band * executing an auxiliary software process through an out-of-band
mechanism, such as querying a digital wallet mechanism, such as querying a digital wallet
The authorization and consent gathering process in GNAP is left The process of gathering authorization and consent in GNAP is left
deliberately flexible to allow for a wide variety of different deliberately flexible to allow for a wide variety of different
deployments, interactions, and methodologies. In this process, the deployments, interactions, and methodologies. In this process, the
AS can gather consent from the RO or apply the RO's policy as AS can gather consent from the RO or apply the RO's policy as
necessitated by the access that has been requested. The AS can necessitated by the access that has been requested. The AS can
sometimes determine which RO needs to prompt for consent based on sometimes determine which RO needs to prompt for consent based on
what has been requested by the client instance, such as a specific RS what has been requested by the client instance, such as a specific RS
record, an identified subject, or a request requiring specific access record, an identified subject, or a request requiring specific access
such as approval by an administrator. In other cases, the request is such as approval by an administrator. In other cases, the request is
applied to whichever RO is present at the time of consent gathering. applied to whichever RO is present at the time of consent gathering.
This pattern is especially prevalent when the end user is sent to the This pattern is especially prevalent when the end user is sent to the
AS for an interactive session, during which the end user takes on the AS for an interactive session, during which the end user takes on the
role of the RO. In these cases, the end user is delegating their own role of the RO. In these cases, the end user is delegating their own
access as RO to the client instance. access as RO to the client instance.
The client instance can indicate that it is capable of facilitating The client instance can indicate that it is capable of facilitating
interaction with the end user, another party, or another piece of interaction with the end user, another party, or another piece of
software through its interaction start (Section 2.5.1) request. software through its interaction start request (Section 2.5.1).
Here, the AS usually needs to interact directly with the end user to Here, the AS usually needs to interact directly with the end user to
determine their identity, determine their status as an RO, and determine their identity, determine their status as an RO, and
collect their consent. If the AS has determined that authorization collect their consent. If the AS has determined that authorization
is required and the AS can support one or more of the requested is required and the AS can support one or more of the requested
interaction start methods, the AS returns the associated interaction interaction start methods, the AS returns the associated interaction
start responses (Section 3.3). The client instance SHOULD initiate start responses (Section 3.3). The client instance SHOULD initiate
one or more of these interaction methods (Section 4.1) in order to one or more of these interaction methods (Section 4.1) in order to
facilitate the granting of the request. If more than one interaction facilitate the granting of the request. If more than one interaction
start method is available, the means by which the client chooses start method is available, the means by which the client chooses
which methods to follow is out of scope of this specification. which methods to follow are out of scope of this specification.
After starting interaction, the client instance can then make a After starting interaction, the client instance can then make a
continuation request (Section 5) either in response to a signal continuation request (Section 5) either in response to a signal
indicating the finish of the interaction (Section 4.2), after a time- indicating the finish of the interaction (Section 4.2), after a time-
based polling, or through some other method defined by an extension based polling, or through some other method defined by an extension
of this specification through the GNAP Interaction Mode Responses of this specification through the "GNAP Interaction Mode Responses"
registry (Section 11.13). registry (Section 10.13).
If the grant request is not in the _approved_ state, the client If the grant request is not in the _approved_ state, the client
instance can repeat the interaction process by sending a grant update instance can repeat the interaction process by sending a grant update
request (Section 5.3) with new interaction (Section 2.5) methods. request (Section 5.3) with new interaction methods (Section 2.5).
The client instance MUST use each interaction method at most once, if The client instance MUST use each interaction method once at most if
a response can be detected. The AS MUST handle any interact request a response can be detected. The AS MUST handle any interact request
as a one-time-use mechanism and SHOULD apply suitable timeouts to any as a one-time-use mechanism and SHOULD apply suitable timeouts to any
interaction start methods provided, including user codes and interaction start methods provided, including user codes and
redirection URIs. The client instance SHOULD apply suitable timeouts redirection URIs. The client instance SHOULD apply suitable timeouts
to any interaction finish method. to any interaction finish method.
In order to support client software deployed in disadvantaged network In order to support client software deployed in disadvantaged network
conditions, the AS MAY allow for processing of the same interaction conditions, the AS MAY allow for processing of the same interaction
method multiple times if the AS can determine that the request is method multiple times if the AS can determine that the request is
from the same party and the results are idempotent. For example, if from the same party and the results are idempotent. For example, if
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first place. However, if the AS in question receives both requests, first place. However, if the AS in question receives both requests,
it could mistakenly process them separately, creating an undefined it could mistakenly process them separately, creating an undefined
state for the client instance. If the AS can determine that both state for the client instance. If the AS can determine that both
requests come from the same origin or under the same session, and the requests come from the same origin or under the same session, and the
requests both came before any additional state change to the grant requests both came before any additional state change to the grant
occurs, the AS can reasonably conclude that the initial response was occurs, the AS can reasonably conclude that the initial response was
not received and the same response can be returned to the client not received and the same response can be returned to the client
instance. instance.
If the AS instead has a means of contacting the RO directly, it could If the AS instead has a means of contacting the RO directly, it could
do so without involving the client instance in its consent gathering do so without involving the client instance in its consent-gathering
process. For example, the AS could push a notification to a known RO process. For example, the AS could push a notification to a known RO
and have the RO approve the pending request asynchronously. These and have the RO approve the pending request asynchronously. These
interactions can be through an interface of the AS itself (such as a interactions can be through an interface of the AS itself (such as a
hosted web page), through another application (such as something hosted web page), through another application (such as something
installed on the RO's device), through a messaging fabric, or any installed on the RO's device), through a messaging fabric, or any
other means. other means.
When interacting with an RO, the AS can do anything it needs to When interacting with an RO, the AS can use various strategies to
determine the authorization of the requested grant, including: determine the authorization of the requested grant, including:
* authenticate the RO, through a local account or some other means * authenticate the RO through a local account or some other means,
such as federated login such as federated login
* validate the RO through presentation of claims, attributes, or * validate the RO through presentation of claims, attributes, or
other information other information
* prompt the RO for consent for the requested delegation * prompt the RO for consent for the requested delegation
* describe to the RO what information is being released, to whom, * describe to the RO what information is being released, to whom,
and for what purpose and for what purpose
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* provide the RO with artifacts such as receipts to facilitate an * provide the RO with artifacts such as receipts to facilitate an
audit trail of authorizations audit trail of authorizations
* allow the RO to deny the requested delegation * allow the RO to deny the requested delegation
The AS is also allowed to request authorization from more than one The AS is also allowed to request authorization from more than one
RO, if the AS deems fit. For example, a medical record might need to RO, if the AS deems fit. For example, a medical record might need to
be released by both an attending nurse and a physician, or both be released by both an attending nurse and a physician, or both
owners of a bank account need to sign off on a transfer request. owners of a bank account need to sign off on a transfer request.
Alternatively, the AS could require N of M possible RO's to approve a Alternatively, the AS could require N of M possible ROs to approve a
given request. In some circumstances, the AS could even determine given request. In some circumstances, the AS could even determine
that the end user present during the interaction is not the that the end user present during the interaction is not the
appropriate RO for a given request and reach out to the appropriate appropriate RO for a given request and reach out to the appropriate
RO asynchronously. RO asynchronously.
The RO is also allowed to define an automated policy at the AS to The RO is also allowed to define an automated policy at the AS to
determine which kind of end user can get access to the resource, and determine which kind of end user can get access to the resource and
under which condition. For instance, such a condition might require under which conditions. For instance, such a condition might require
the end user login and the acceptance of the RO's legal provisions. the end user to log in and accept the RO's legal provisions.
Alternatively, client software could be acting without an end user, Alternatively, client software could be acting without an end user,
and the RO's policy allows issuance of access tokens to specific and the RO's policy allows issuance of access tokens to specific
instances of that client software without human interaction. instances of that client software without human interaction.
While all of these cases are supported by GNAP, the details of their While all of these cases are supported by GNAP, the details of their
implementation, and for determining which RO's or related policies implementation and the methods for determining which ROs or related
are required for a given request, are out of scope for this policies are required for a given request are out of scope for this
specification. specification.
4.1. Starting Interaction With the End User 4.1. Starting Interaction with the End User
When a grant request is in the _pending_ state, the interaction start When a grant request is in the _pending_ state, the interaction start
methods sent by the client instance can be used to facilitate methods sent by the client instance can be used to facilitate
interaction with the end user. To initiate an interaction start interaction with the end user. To initiate an interaction start
method indicated by the interaction start responses (Section 3.3) method indicated by the interaction start responses (Section 3.3)
from the AS, the client instance follows the steps defined by that from the AS, the client instance follows the steps defined by that
interaction start mode. The actions of the client instance required interaction start mode. The actions of the client instance required
for the interaction start modes defined in this specification are for the interaction start modes defined in this specification are
described in the following sections. Interaction start modes defined described in the following subsections. Interaction start modes
in extensions to this specification MUST define the expected actions defined in extensions to this specification MUST define the expected
of the client software when that interaction start mode is used. actions of the client software when that interaction start mode is
used.
If the client instance does not start an interaction start mode If the client instance does not start an interaction start mode
within an AS-determined amount of time, the AS MUST reject attempts within an AS-determined amount of time, the AS MUST reject attempts
to use the interaction start modes. If the client instance has to use the interaction start modes. If the client instance has
already begun one interaction start mode and the interaction has been already begun one interaction start mode and the interaction has been
successfully completed, the AS MUST reject attempts to use other successfully completed, the AS MUST reject attempts to use other
interaction start modes. For example, if a user code has been interaction start modes. For example, if a user code has been
successfully entered for a grant request, the AS will need to reject successfully entered for a grant request, the AS will need to reject
requests to an arbitrary redirect URI on the same grant request in requests to an arbitrary redirect URI on the same grant request in
order to prevent an attacker from capturing and altering an active order to prevent an attacker from capturing and altering an active
authorization process. authorization process.
4.1.1. Interaction at a Redirected URI 4.1.1. Interaction at a Redirected URI
When the end user is directed to an arbitrary URI through the When the end user is directed to an arbitrary URI through the
"redirect" (Section 3.3.1) mode, the client instance facilitates "redirect" mode (Section 3.3.1), the client instance facilitates
opening the URI through the end user's web browser. The client opening the URI through the end user's web browser. The client
instance could launch the URI through the system browser, provide a instance could launch the URI through the system browser, provide a
clickable link, redirect the user through HTTP response codes, or clickable link, redirect the user through HTTP response codes, or
display the URI in a form the end user can use to launch such as a display the URI in a form the end user can use to launch, such as a
multidimensional barcode. In all cases, the URI is accessed with an multidimensional barcode. In all cases, the URI is accessed with an
HTTP GET request, and the resulting page is assumed to allow direct HTTP GET request, and the resulting page is assumed to allow direct
interaction with the end user through an HTTP user agent. With this interaction with the end user through an HTTP user agent. With this
method, it is common (though not required) for the RO to be the same method, it is common (though not required) for the RO to be the same
party as the end user, since the client instance has to communicate party as the end user, since the client instance has to communicate
the redirection URI to the end user. the redirection URI to the end user.
In many cases, the URI indicates a web page hosted at the AS, In many cases, the URI indicates a web page hosted at the AS,
allowing the AS to authenticate the end user as the RO and allowing the AS to authenticate the end user as the RO and
interactively provide consent. The URI value is used to identify the interactively provide consent. The URI value is used to identify the
grant request being authorized. If the URI cannot be associated with grant request being authorized. If the URI cannot be associated with
a currently active request, the AS MUST display an error to the RO a currently active request, the AS MUST display an error to the RO
and MUST NOT attempt to redirect the RO back to any client instance and MUST NOT attempt to redirect the RO back to any client instance,
even if a redirect finish method is supplied (Section 2.5.2.1). If even if a redirect finish method is supplied (Section 2.5.2.1). If
the URI is not hosted by the AS directly, the means of communication the URI is not hosted by the AS directly, the means of communication
between the AS and the service provided by this URI are out of scope between the AS and the service provided by this URI are out of scope
for this specification. for this specification.
The client instance MUST NOT modify the URI when launching it, in The client instance MUST NOT modify the URI when launching it; in
particular the client instance MUST NOT add any parameters to the particular, the client instance MUST NOT add any parameters to the
URI. The URI MUST be reachable from the end user's browser, though URI. The URI MUST be reachable from the end user's browser, though
the URI MAY be opened on a separate device from the client instance the URI MAY be opened on a separate device from the client instance
itself. The URI MUST be accessible from an HTTP GET request and MUST itself. The URI MUST be accessible from an HTTP GET request, and it
be protected by HTTPS, be hosted on a server local to the RO's MUST be protected by HTTPS, be hosted on a server local to the RO's
browser ("localhost"), or use an application-specific URI scheme that browser ("localhost"), or use an application-specific URI scheme that
is loaded on the end user's device. is loaded on the end user's device.
4.1.2. Interaction at the Static User Code URI 4.1.2. Interaction at the Static User Code URI
When the end user is directed to enter a short code through the When the end user is directed to enter a short code through the
"user_code" (Section 3.3.3) mode, the client instance communicates "user_code" mode (Section 3.3.3), the client instance communicates
the user code to the end user and directs the end user to enter that the user code to the end user and directs the end user to enter that
code at an associated URI. The client instance MAY format the user code at an associated URI. The client instance MAY format the user
code in such a way as to facilitate memorability and transfer of the code in such a way as to facilitate memorability and transfer of the
code, so long as this formatting does not alter the value as accepted code, so long as this formatting does not alter the value as accepted
at the user code URI. For example, a client instance receiving the at the user code URI. For example, a client instance receiving the
user code "A1BC3DFF" could choose to display this to the user as user code "A1BC3DFF" could choose to display this to the user as
"A1BC 3DFF", breaking up the long string into two shorter strings. "A1BC 3DFF", breaking up the long string into two shorter strings.
When processing input codes, the AS MUST transform the input string When processing input codes, the AS MUST transform the input string
to remove invalid characters. In the above example, the space in to remove invalid characters. In the above example, the space in
between the two parts would be removed upon its entry into the between the two parts would be removed upon its entry into the
interactive form at the user code URI. Additionally, the AS MUST interactive form at the user code URI. Additionally, the AS MUST
treat user input as case insensitive. For example, if the user treat user input as case insensitive. For example, if the user
inputs the string "a1bc 3DFF", the AS will treat the input the same inputs the string "a1bc 3DFF", the AS will treat the input the same
as "A1BC3DFF". To facilitate this, it is RECOMMENDED that the AS use as "A1BC3DFF". To facilitate this, it is RECOMMENDED that the AS use
only ASCII letters and numbers as valid characters for the user code. only ASCII letters and numbers as valid characters for the user code.
It is RECOMMENDED that the AS choose from character values that are It is RECOMMENDED that the AS choose from character values that are
easily copied and typed without ambiguity. For example, some glyphs easily copied and typed without ambiguity. For example, some glyphs
have multiple Unicode code points for the same visual character, and have multiple Unicode code points for the same visual character, and
the end-user could potentially type a different character than what the end user could potentially type a different character than what
the AS has returned. For additional considerations of the AS has returned. For additional considerations of
internationalized character strings, see [RFC8264] internationalized character strings, see [RFC8264].
This mode is designed to be used when the client instance is not able This mode is designed to be used when the client instance is not able
to communicate or facilitate launching an arbitrary URI. The to communicate or facilitate launching an arbitrary URI. The
associated URI could be statically configured with the client associated URI could be statically configured with the client
instance or in the client software's documentation. As a instance or in the client software's documentation. As a
consequence, these URIs SHOULD be short. The user code URI MUST be consequence, these URIs SHOULD be short. The user code URI MUST be
reachable from the end user's browser, though the URI is usually reachable from the end user's browser, though the URI is usually
opened on a separate device from the client instance itself. The URI opened on a separate device from the client instance itself. The URI
MUST be accessible from an HTTP GET request and MUST be protected by MUST be accessible from an HTTP GET request, and it MUST be protected
HTTPS, be hosted on a server local to the RO's browser ("localhost"), by HTTPS, be hosted on a server local to the RO's browser
or use an application-specific URI scheme that is loaded on the end ("localhost"), or use an application-specific URI scheme that is
user's device. loaded on the end user's device.
In many cases, the URI indicates a web page hosted at the AS, In many cases, the URI indicates a web page hosted at the AS,
allowing the AS to authenticate the end user as the RO and allowing the AS to authenticate the end user as the RO and
interactively provide consent. The value of the user code is used to interactively provide consent. The value of the user code is used to
identify the grant request being authorized. If the user code cannot identify the grant request being authorized. If the user code cannot
be associated with a currently active request, the AS MUST display an be associated with a currently active request, the AS MUST display an
error to the RO and MUST NOT attempt to redirect the RO back to any error to the RO and MUST NOT attempt to redirect the RO back to any
client instance even if a redirect finish method is supplied client instance, even if a redirect finish method is supplied
(Section 2.5.2.1). If the interaction component at the user code URI (Section 2.5.2.1). If the interaction component at the user code URI
is not hosted by the AS directly, the means of communication between is not hosted by the AS directly, the means of communication between
the AS and this URI, including communication of the user code itself, the AS and this URI, including communication of the user code itself,
are out of scope for this specification. are out of scope for this specification.
When the RO enters this code at the user code URI, the AS MUST When the RO enters this code at the user code URI, the AS MUST
uniquely identify the pending request that the code was associated uniquely identify the pending request that the code was associated
with. If the AS does not recognize the entered code, the interaction with. If the AS does not recognize the entered code, the interaction
component MUST display an error to the user. If the AS detects too component MUST display an error to the user. If the AS detects too
many unrecognized code enter attempts, the interaction component many unrecognized code enter attempts, the interaction component
SHOULD display an error to the user indicating too many attempts and SHOULD display an error to the user indicating too many attempts and
MAY take additional actions such as slowing down the input MAY take additional actions such as slowing down the input
interactions. The user should be warned as such an error state is interactions. The user should be warned as such an error state is
approached, if possible. approached, if possible.
4.1.3. Interaction at a Dynamic User Code URI 4.1.3. Interaction at a Dynamic User Code URI
When the end user is directed to enter a short code through the When the end user is directed to enter a short code through the
"user_code_uri" (Section 3.3.4) mode, the client instance "user_code_uri" mode (Section 3.3.4), the client instance
communicates the user code and associated URI to the end user and communicates the user code and associated URI to the end user and
directs the end user to enter that code at the URI. The client directs the end user to enter that code at the URI. The client
instance MAY format the user code in such a way as to facilitate instance MAY format the user code in such a way as to facilitate
memorability and transfer of the code, so long as this formatting memorability and transfer of the code, so long as this formatting
does not alter the value as accepted at the user code URI. For does not alter the value as accepted at the user code URI. For
example, a client instance receiving the user code "A1BC3DFF" could example, a client instance receiving the user code "A1BC3DFF" could
choose to display this to the user as "A1BC 3DFF", breaking up the choose to display this to the user as "A1BC 3DFF", breaking up the
long string into two shorter strings. long string into two shorter strings.
When processing input codes, the AS MUST transform the input string When processing input codes, the AS MUST transform the input string
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This mode is used when the client instance is not able to facilitate This mode is used when the client instance is not able to facilitate
launching a complex arbitrary URI but can communicate arbitrary launching a complex arbitrary URI but can communicate arbitrary
values like URIs. As a consequence, these URIs SHOULD be short values like URIs. As a consequence, these URIs SHOULD be short
enough to allow the URI to be typed by the end user, such as a total enough to allow the URI to be typed by the end user, such as a total
length of 20 characters or fewer. The client instance MUST NOT length of 20 characters or fewer. The client instance MUST NOT
modify the URI when communicating it to the end user; in particular modify the URI when communicating it to the end user; in particular
the client instance MUST NOT add any parameters to the URI. The user the client instance MUST NOT add any parameters to the URI. The user
code URI MUST be reachable from the end user's browser, though the code URI MUST be reachable from the end user's browser, though the
URI is usually be opened on a separate device from the client URI is usually be opened on a separate device from the client
instance itself. The URI MUST be accessible from an HTTP GET request instance itself. The URI MUST be accessible from an HTTP GET
and MUST be protected by HTTPS, be hosted on a server local to the request, and it MUST be protected by HTTPS, be hosted on a server
RO's browser ("localhost"), or use an application-specific URI scheme local to the RO's browser ("localhost"), or use an application-
that is loaded on the end user's device. specific URI scheme that is loaded on the end user's device.
In many cases, the URI indicates a web page hosted at the AS, In many cases, the URI indicates a web page hosted at the AS,
allowing the AS to authenticate the end user as the RO and allowing the AS to authenticate the end user as the RO and
interactively provide consent. The value of the user code is used to interactively provide consent. The value of the user code is used to
identify the grant request being authorized. If the user code cannot identify the grant request being authorized. If the user code cannot
be associated with a currently active request, the AS MUST display an be associated with a currently active request, the AS MUST display an
error to the RO and MUST NOT attempt to redirect the RO back to any error to the RO and MUST NOT attempt to redirect the RO back to any
client instance even if a redirect finish method is supplied client instance, even if a redirect finish method is supplied
(Section 2.5.2.1). If the interaction component at the user code URI (Section 2.5.2.1). If the interaction component at the user code URI
is not hosted by the AS directly, the means of communication between is not hosted by the AS directly, the means of communication between
the AS and this URI, including communication of the user code itself, the AS and this URI, including communication of the user code itself,
are out of scope for this specification. are out of scope for this specification.
When the RO enters this code at the given URI, the AS MUST uniquely When the RO enters this code at the given URI, the AS MUST uniquely
identify the pending request that the code was associated with. If identify the pending request that the code was associated with. If
the AS does not recognize the entered code, the interaction component the AS does not recognize the entered code, the interaction component
MUST display an error to the user. If the AS detects too many MUST display an error to the user. If the AS detects too many
unrecognized code enter attempts, the interaction component SHOULD unrecognized code enter attempts, the interaction component SHOULD
display an error to the user indicating too many attempts and MAY display an error to the user indicating too many attempts and MAY
take additional actions such as slowing down the input interactions. take additional actions such as slowing down the input interactions.
The user should be warned as such an error state is approached, if The user should be warned as such an error state is approached, if
possible. possible.
4.1.4. Interaction through an Application URI 4.1.4. Interaction through an Application URI
When the client instance is directed to launch an application through When the client instance is directed to launch an application through
the "app" (Section 3.3.2) mode, the client launches the URI as the "app" mode (Section 3.3.2), the client launches the URI as
appropriate to the system, such as through a deep link or custom URI appropriate to the system, such as through a deep link or custom URI
scheme registered to a mobile application. The means by which the AS scheme registered to a mobile application. The means by which the AS
and the launched application communicate with each other and perform and the launched application communicate with each other and perform
any of the required actions are out of scope for this specification. any of the required actions are out of scope for this specification.
4.2. Post-Interaction Completion 4.2. Post-Interaction Completion
If an interaction "finish" (Section 3.3.5) method is associated with If an interaction "finish" method (Section 3.3.5) is associated with
the current request, the AS MUST follow the appropriate method upon the current request, the AS MUST follow the appropriate method upon
completion of interaction in order to signal the client instance to completion of interaction in order to signal the client instance to
continue, except for some limited error cases discussed below. If a continue, except for some limited error cases discussed below. If a
finish method is not available, the AS SHOULD instruct the RO to finish method is not available, the AS SHOULD instruct the RO to
return to the client instance upon completion. In such cases, it is return to the client instance upon completion. In such cases, it is
expected that the client instance will poll the continuation endpoint expected that the client instance will poll the continuation endpoint
as described in Section 5.2. as described in Section 5.2.
The AS MUST create an interaction reference and associate that The AS MUST create an interaction reference and associate that
reference with the current interaction and the underlying pending reference with the current interaction and the underlying pending
request. The interaction reference value is an ASCII string request. The interaction reference value is an ASCII string
consisting of only unreserved characters per Section 2.3 of consisting of only unreserved characters per Section 2.3 of
[RFC3986]. The interaction reference value MUST be sufficiently [RFC3986]. The interaction reference value MUST be sufficiently
random so as not to be guessable by an attacker. The interaction random so as not to be guessable by an attacker. The interaction
reference MUST be one-time-use to prevent interception and replay reference MUST be one-time-use to prevent interception and replay
attacks. attacks.
The AS MUST calculate a hash value based on the client instance and The AS MUST calculate a hash value based on the client instance, AS
AS nonces and the interaction reference, as described in nonces, and the interaction reference, as described in Section 4.2.3.
Section 4.2.3. The client instance will use this value to validate The client instance will use this value to validate the "finish"
the "finish" call. call.
All interaction finish methods MUST define a way to convey the hash All interaction finish methods MUST define a way to convey the hash
and interaction reference back to the client instance. When an and interaction reference back to the client instance. When an
interaction finish method is used, the client instance MUST present interaction finish method is used, the client instance MUST present
the interaction reference back to the AS as part of its continuation the interaction reference back to the AS as part of its continuation
request (Section 5.1). request (Section 5.1).
Note that in many error cases, such as when the RO has denied access, Note that in many error cases, such as when the RO has denied access,
the "finish" method is still enacted by the AS. This pattern allows the "finish" method is still enacted by the AS. This pattern allows
the client instance to potentially recover from the error state by the client instance to potentially recover from the error state by
modifying its request or providing additional information directly to modifying its request or providing additional information directly to
the AS in a continuation request. The AS MUST NOT follow the the AS in a continuation request. The AS MUST NOT follow the
"finish" method in the following circumstances: "finish" method in the following circumstances:
* The AS has determined that any URIs involved with the finish * The AS has determined that any URIs involved with the finish
method are dangerous or blocked. method are dangerous or blocked.
* The AS cannot determine which ongoing grant request is being * The AS cannot determine which ongoing grant request is being
referenced. referenced.
* The ongoing grant request has been cancelled or otherwise blocked. * The ongoing grant request has been canceled or otherwise blocked.
4.2.1. Completing Interaction with a Browser Redirect to the Callback 4.2.1. Completing Interaction with a Browser Redirect to the Callback
URI URI
When using the redirect interaction finish method defined in When using the redirect interaction finish method defined in Sections
Section 2.5.2.1 and Section 3.3.5, the AS signals to the client 2.5.2.1 and 3.3.5, the AS signals to the client instance that
instance that interaction is complete and the request can be interaction is complete and the request can be continued by directing
continued by directing the RO (in their browser) back to the client the RO (in their browser) back to the client instance's redirect URI.
instance's redirect URI.
The AS secures this redirect by adding the hash and interaction The AS secures this redirect by adding the hash and interaction
reference as query parameters to the client instance's redirect URI. reference as query parameters to the client instance's redirect URI.
hash: The interaction hash value as described in Section 4.2.3. hash: The interaction hash value as described in Section 4.2.3.
REQUIRED. REQUIRED.
interact_ref: The interaction reference generated for this interact_ref: The interaction reference generated for this
interaction. REQUIRED. interaction. REQUIRED.
The means of directing the RO to this URI are outside the scope of The means of directing the RO to this URI are outside the scope of
this specification, but common options include redirecting the RO this specification, but common options include redirecting the RO
from a web page and launching the system browser with the target URI. from a web page and launching the system browser with the target URI.
See Section 13.19 for considerations on which HTTP status code to use See Section 11.19 for considerations on which HTTP status code to use
when redirecting a request that potentially contains credentials. when redirecting a request that potentially contains credentials.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
https://client.example.net/return/123455\ https://client.example.net/return/123455\
?hash=x-gguKWTj8rQf7d7i3w3UhzvuJ5bpOlKyAlVpLxBffY\ ?hash=x-gguKWTj8rQf7d7i3w3UhzvuJ5bpOlKyAlVpLxBffY\
&interact_ref=4IFWWIKYBC2PQ6U56NL1 &interact_ref=4IFWWIKYBC2PQ6U56NL1
The client instance MUST be able to process a request on the URI. If The client instance MUST be able to process a request on the URI. If
the URI is HTTP, the request MUST be an HTTP GET. the URI is HTTP, the request MUST be an HTTP GET.
When receiving the request, the client instance MUST parse the query When receiving the request, the client instance MUST parse the query
parameters to extract the hash and interaction reference values. The parameters to extract the hash and interaction reference values. The
client instance MUST calculate and validate the hash value as client instance MUST calculate and validate the hash value as
described in Section 4.2.3. If the hash validates, the client described in Section 4.2.3. If the hash validates, the client
instance sends a continuation request to the AS as described in instance sends a continuation request to the AS as described in
Section 5.1 using the interaction reference value received here. If Section 5.1, using the interaction reference value received here. If
the hash does not validate, the client instance MUST NOT send the the hash does not validate, the client instance MUST NOT send the
interaction reference to the AS. interaction reference to the AS.
4.2.2. Completing Interaction with a Direct HTTP Request Callback 4.2.2. Completing Interaction with a Direct HTTP Request Callback
When using the push interaction finish method defined in When using the push interaction finish method defined in Sections
Section 2.5.2.1 and Section 3.3.5, the AS signals to the client 2.5.2.1 and 3.3.5, the AS signals to the client instance that
instance that interaction is complete and the request can be interaction is complete and the request can be continued by sending
continued by sending an HTTP POST request to the client instance's an HTTP POST request to the client instance's callback URI.
callback URI.
The HTTP message content is a JSON object consisting of the following The HTTP message content is a JSON object consisting of the following
two fields: two fields:
hash (string): The interaction hash value as described in hash (string): The interaction hash value as described in
Section 4.2.3. REQUIRED. Section 4.2.3. REQUIRED.
interact_ref (string) The interaction reference generated for this interact_ref (string): The interaction reference generated for this
interaction. REQUIRED. interaction. REQUIRED.
POST /push/554321 HTTP/1.1 POST /push/554321 HTTP/1.1
Host: client.example.net Host: client.example.net
Content-Type: application/json Content-Type: application/json
{ {
"hash": "pjdHcrti02HLCwGU3qhUZ3wZXt8IjrV_BtE3oUyOuKNk", "hash": "pjdHcrti02HLCwGU3qhUZ3wZXt8IjrV_BtE3oUyOuKNk",
"interact_ref": "4IFWWIKYBC2PQ6U56NL1" "interact_ref": "4IFWWIKYBC2PQ6U56NL1"
} }
Since the AS is making an outbound connection to a URI supplied by an Since the AS is making an outbound connection to a URI supplied by an
outside party (the client instance), the AS MUST protect itself outside party (the client instance), the AS MUST protect itself
against SSRF attacks when making this call as discussed in against Server-Side Request Forgery (SSRF) attacks when making this
Section 13.34. call, as discussed in Section 11.34.
When receiving the request, the client instance MUST parse the JSON When receiving the request, the client instance MUST parse the JSON
object and validate the hash value as described in Section 4.2.3. If object and validate the hash value as described in Section 4.2.3. If
either fails, the client instance MUST return an unknown_interaction either fails, the client instance MUST return an unknown_interaction
error (Section 3.6). If the hash validates, the client instance error (Section 3.6). If the hash validates, the client instance
sends a continuation request to the AS as described in Section 5.1 sends a continuation request to the AS as described in Section 5.1,
using the interaction reference value received here. using the interaction reference value received here.
4.2.3. Calculating the interaction hash 4.2.3. Calculating the Interaction Hash
The "hash" parameter in the request to the client instance's callback The "hash" parameter in the request to the client instance's callback
URI ties the front channel response to an ongoing request by using URI ties the front-channel response to an ongoing request by using
values known only to the parties involved. This security mechanism values known only to the parties involved. This security mechanism
allows the client instance to protect itself against several kinds of allows the client instance to protect itself against several kinds of
session fixation and injection attacks as discussed in Section 13.25 session fixation and injection attacks as discussed in Section 11.25.
and related sections. The AS MUST always provide this hash, and the The AS MUST always provide this hash, and the client instance MUST
client instance MUST validate the hash when received. validate the hash when received.
To calculate the "hash" value, the party doing the calculation To calculate the "hash" value, the party doing the calculation
creates a hash base string by concatenating the following values in creates a hash base string by concatenating the following values in
the following order using a single newline (0x0A) character to the following order using a single newline (0x0A) character to
separate them: separate them:
* the "nonce" value sent by the client instance in the interaction * the "nonce" value sent by the client instance in the interaction
"finish" section of the initial request (Section 2.5.2) finish field of the initial request (Section 2.5.2)
* the AS's nonce value from the interaction finish response * the AS's nonce value from the interaction finish response
(Section 3.3.5) (Section 3.3.5)
* the "interact_ref" returned from the AS as part of the interaction * the "interact_ref" returned from the AS as part of the interaction
finish method (Section 4.2) finish method (Section 4.2)
* the grant endpoint URI the client instance used to make its * the grant endpoint URI the client instance used to make its
initial request (Section 2) initial request (Section 2)
There is no padding or whitespace before or after any of the lines, There is no padding or whitespace before or after any of the lines
and no trailing newline character. The following non-normative and no trailing newline character. The following non-normative
example shows a constructed hash base string consisting of these four example shows a constructed hash base string consisting of these four
elements. elements.
VJLO6A4CATR0KRO VJLO6A4CATR0KRO
MBDOFXG4Y5CVJCX821LH MBDOFXG4Y5CVJCX821LH
4IFWWIKYB2PQ6U56NL1 4IFWWIKYB2PQ6U56NL1
https://server.example.com/tx https://server.example.com/tx
The party then hashes the bytes of the ASCII encoding of this string The party then hashes the bytes of the ASCII encoding of this string
with the appropriate algorithm based on the "hash_method" parameter with the appropriate algorithm based on the "hash_method" parameter
under the "finish" key of the interaction finish request under the "finish" key of the interaction finish request
(Section 2.5.2). The resulting byte array from the hash function is (Section 2.5.2). The resulting byte array from the hash function is
then encoded using URL-Safe Base64 with no padding [RFC4648]. The then encoded using URL-Safe base64 with no padding [RFC4648]. The
resulting string is the hash value. resulting string is the hash value.
If provided, the "hash_method" value MUST be one of the hash name If provided, the "hash_method" value MUST be one of the hash name
strings defined in the IANA Named Information Hash Algorithm Registry strings defined in the IANA "Named Information Hash Algorithm
[HASH-ALG]. If the "hash_method" value is not present in the client Registry" [HASH-ALG]. If the "hash_method" value is not present in
instance's request, the algorithm defaults to "sha-256". the client instance's request, the algorithm defaults to "sha-256".
For example, the "sha-256" hash method consists of hashing the input For example, the "sha-256" hash method consists of hashing the input
string with the 256-bit SHA2 algorithm. The following is the encoded string with the 256-bit SHA2 algorithm. The following is the encoded
"sha-256" hash of the above example hash base string. "sha-256" hash of the hash base string in the example above.
x-gguKWTj8rQf7d7i3w3UhzvuJ5bpOlKyAlVpLxBffY x-gguKWTj8rQf7d7i3w3UhzvuJ5bpOlKyAlVpLxBffY
For another example, the "sha3-512" hash method consists of hashing As another example, the "sha3-512" hash method consists of hashing
the input string with the 512-bit SHA3 algorithm. The following is the input string with the 512-bit SHA3 algorithm. The following is
the encoded "sha3-512" hash of the above example hash base string. the encoded "sha3-512" hash of the hash base string in the example
above.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
pyUkVJSmpqSJMaDYsk5G8WCvgY91l-agUPe1wgn-cc5rUtN69gPI2-S_s-Eswed8iB4\ pyUkVJSmpqSJMaDYsk5G8WCvgY91l-agUPe1wgn-cc5rUtN69gPI2-S_s-Eswed8iB4\
PJ_a5Hg6DNi7qGgKwSQ PJ_a5Hg6DNi7qGgKwSQ
5. Continuing a Grant Request 5. Continuing a Grant Request
While it is possible for the AS to return an approved grant response While it is possible for the AS to return an approved grant response
(Section 3) with all the client instance's requested information (Section 3) with all the client instance's requested information
skipping to change at page 87, line 43 skipping to change at line 3936
The ability to continue an already-started request allows the client The ability to continue an already-started request allows the client
instance to perform several important functions, including presenting instance to perform several important functions, including presenting
additional information from interaction, modifying the initial additional information from interaction, modifying the initial
request, and revoking a grant request in progress. request, and revoking a grant request in progress.
To enable this ongoing negotiation, the AS provides a continuation To enable this ongoing negotiation, the AS provides a continuation
API to the client software. The AS returns a continue field in the API to the client software. The AS returns a continue field in the
response (Section 3.1) that contains information the client instance response (Section 3.1) that contains information the client instance
needs to access this API, including a URI to access as well as a needs to access this API, including a URI to access as well as a
special access token to use during the requests, called the special access token to use during the requests, called the
_continuation access token_. "continuation access token".
All requests to the continuation API are protected by a bound All requests to the continuation API are protected by a bound
continuation access token. The continuation access token is bound to continuation access token. The continuation access token is bound to
the same key and method the client instance used to make the initial the same key and method the client instance used to make the initial
request (or its most recent rotation). As a consequence, when the request (or its most recent rotation). As a consequence, when the
client instance makes any calls to the continuation URI, the client client instance makes any calls to the continuation URI, the client
instance MUST present the continuation access token as described in instance MUST present the continuation access token as described in
Section 7.2 and present proof of the client instance's key (or its Section 7.2 and present proof of the client instance's key (or its
most recent rotation) by signing the request as described in most recent rotation) by signing the request as described in
Section 7.3. The AS MUST validate the signature and ensure that it Section 7.3. The AS MUST validate the signature and ensure that it
is bound to the appropriate key for the continuation access token. is bound to the appropriate key for the continuation access token.
Access tokens other than the continuation access tokens MUST NOT be Access tokens other than the continuation access tokens MUST NOT be
usable for continuation requests. Conversely, continuation access usable for continuation requests. Conversely, continuation access
tokens MUST NOT be usable to make authorized requests to RS's, even tokens MUST NOT be usable to make authorized requests to RSs, even if
if co-located within the AS. co-located within the AS.
In the following non-normative example, the client instance makes a In the following non-normative example, the client instance makes a
POST request to a unique URI and signs the request with HTTP Message POST request to a unique URI and signs the request with HTTP message
Signatures: signatures:
POST /continue/KSKUOMUKM HTTP/1.1 POST /continue/KSKUOMUKM HTTP/1.1
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Host: server.example.com Host: server.example.com
Content-Length: 0 Content-Length: 0
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
The AS MUST be able to tell from the client instance's request which The AS MUST be able to tell from the client instance's request which
specific ongoing request is being accessed, using a combination of specific ongoing request is being accessed, using a combination of
the continuation URI and the continuation access token. If the AS the continuation URI and the continuation access token. If the AS
cannot determine a single active grant request to map the cannot determine a single active grant request to map the
continuation request to, the AS MUST return an invalid_continuation continuation request to, the AS MUST return an invalid_continuation
error (Section 3.6). error (Section 3.6).
In the following non-normative example, the client instance makes a In the following non-normative example, the client instance makes a
POST request to a stable continuation endpoint URI with the POST request to a stable continuation endpoint URI with the
interaction reference (Section 5.1), includes the access token, and interaction reference (Section 5.1), includes the access token, and
signs with HTTP Message Signatures: signs with HTTP message signatures:
POST /continue HTTP/1.1 POST /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Content-Digest: sha-256=... Content-Digest: sha-256=...
{ {
"interact_ref": "4IFWWIKYBC2PQ6U56NL1" "interact_ref": "4IFWWIKYBC2PQ6U56NL1"
} }
In following non-normative alternative example, the client instance In the following non-normative alternative example, the client
had been provided a continuation URI unique to this ongoing grant instance had been provided a continuation URI unique to this ongoing
request: grant request:
POST /tx/rxgIIEVMBV-BQUO7kxbsp HTTP/1.1 POST /tx/rxgIIEVMBV-BQUO7kxbsp HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP eyJhbGciOiJub25lIiwidHlwIjoiYmFkIn0 Authorization: GNAP eyJhbGciOiJub25lIiwidHlwIjoiYmFkIn0
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Content-Digest: sha-256=... Content-Digest: sha-256=...
{ {
skipping to change at page 89, line 46 skipping to change at line 4018
If a wait parameter was included in the continuation response If a wait parameter was included in the continuation response
(Section 3.1), the client instance MUST NOT call the continuation URI (Section 3.1), the client instance MUST NOT call the continuation URI
prior to waiting the number of seconds indicated. If no wait period prior to waiting the number of seconds indicated. If no wait period
is indicated, the client instance MUST NOT poll immediately and is indicated, the client instance MUST NOT poll immediately and
SHOULD wait at least 5 seconds. If the client instance does not SHOULD wait at least 5 seconds. If the client instance does not
respect the given wait period, the AS MUST return the too_fast error respect the given wait period, the AS MUST return the too_fast error
(Section 3.6). (Section 3.6).
The response from the AS is a JSON object of a grant response and MAY The response from the AS is a JSON object of a grant response and MAY
contain any of the fields described in Section 3, as described in contain any of the fields described in Section 3, as described in
more detail in the sections below. more detail in the subsections below.
If the AS determines that the client instance can make further If the AS determines that the client instance can make further
requests to the continuation API, the AS MUST include a new requests to the continuation API, the AS MUST include a new
"continue" response (Section 3.1). The new continue response MUST continuation response (Section 3.1). The new continuation response
include a continuation access token as well, and this token SHOULD be MUST include a continuation access token as well, and this token
a new access token, invalidating the previous access token. If the SHOULD be a new access token, invalidating the previous access token.
AS does not return a new continue response, the client instance MUST If the AS does not return a new continuation response, the client
NOT make an additional continuation request. If a client instance instance MUST NOT make an additional continuation request. If a
does so, the AS MUST return an invalid_continuation error client instance does so, the AS MUST return an invalid_continuation
(Section 3.6). error (Section 3.6).
For continuation functions that require the client instance to send a For continuation functions that require the client instance to send
message content, the content MUST be a JSON object. message content, the content MUST be a JSON object.
For all requests to the grant continuation API, the AS MAY make use For all requests to the grant continuation API, the AS MAY make use
of long polling mechanisms such as discussed in [RFC6202]. That is of long polling mechanisms such as those discussed in [RFC6202].
to say, instead of returning the current status immediately, the long That is to say, instead of returning the current status immediately,
polling technique allows the AS additional time to process and the long polling technique allows the AS additional time to process
fulfill the request before returning the HTTP response to the client and fulfill the request before returning the HTTP response to the
instance. For example, when the AS receives a continuation request client instance. For example, when the AS receives a continuation
but the grant request is in the _processing_ state, the AS could wait request but the grant request is in the _processing_ state, the AS
until the grant request has moved to the _pending_ or _approved_ could wait until the grant request has moved to the _pending_ or
state before returning the response message. _approved_ state before returning the response message.
5.1. Continuing After a Completed Interaction 5.1. Continuing after a Completed Interaction
When the AS responds to the client instance's finish method as in When the AS responds to the client instance's finish method as in
Section 4.2.1, this response includes an interaction reference. The Section 4.2.1, this response includes an interaction reference. The
client instance MUST include that value as the field interact_ref in client instance MUST include that value as the field interact_ref in
a POST request to the continuation URI. a POST request to the continuation URI.
POST /continue HTTP/1.1 POST /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
skipping to change at page 91, line 6 skipping to change at line 4072
Since the interaction reference is a one-time-use value as described Since the interaction reference is a one-time-use value as described
in Section 4.2.1, if the client instance needs to make additional in Section 4.2.1, if the client instance needs to make additional
continuation calls after this request, the client instance MUST NOT continuation calls after this request, the client instance MUST NOT
include the interaction reference in subsequent calls. If the AS include the interaction reference in subsequent calls. If the AS
detects a client instance submitting an interaction reference when detects a client instance submitting an interaction reference when
the request is not in the _pending_ state, the AS MUST return a the request is not in the _pending_ state, the AS MUST return a
too_many_attempts error (Section 3.6) and SHOULD invalidate the too_many_attempts error (Section 3.6) and SHOULD invalidate the
ongoing request by moving it to the _finalized_ state. ongoing request by moving it to the _finalized_ state.
If the grant request is in the _approved_ state, the grant response If the grant request is in the _approved_ state, the grant response
(Section 3) MAY contain any newly-created access tokens (Section 3.2) (Section 3) MAY contain any newly created access tokens (Section 3.2)
or newly-released subject information (Section 3.4). The response or newly released subject information (Section 3.4). The response
MAY contain a new "continue" response (Section 3.1) as described MAY contain a new continuation response (Section 3.1) as described
above. The response SHOULD NOT contain any interaction responses above. The response SHOULD NOT contain any interaction responses
(Section 3.3). (Section 3.3).
If the grant request is in the _pending_ state, the grant response If the grant request is in the _pending_ state, the grant response
(Section 3) MUST NOT contain access tokens or subject information, (Section 3) MUST NOT contain access tokens or subject information and
and MAY contain a new interaction responses (Section 3.3) to any MAY contain a new interaction response (Section 3.3) to any
interaction methods that have not been exhausted at the AS. interaction methods that have not been exhausted at the AS.
For example, if the request is successful in causing the AS to issue For example, if the request is successful in causing the AS to issue
access tokens and release opaque subject claims, the response could access tokens and release opaque subject claims, the response could
look like this: look like this:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
{ {
"access_token": { "access_token": {
skipping to change at page 91, line 41 skipping to change at line 4107
} }
}, },
"subject": { "subject": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
} ] } ]
} }
} }
With the above example, the client instance can not make an With the above example, the client instance cannot make an additional
additional continuation request because a continue field is not continuation request because a continue field is not included.
included.
In the following non-normative example, the RO has denied the client In the following non-normative example, the RO has denied the client
instance's request and the AS responds with the following response: instance's request, and the AS responds with the following response:
{ {
"error": "user_denied", "error": "user_denied",
"continue": { "continue": {
"access_token": { "access_token": {
"value": "33OMUKMKSKU80UPRY5NM" "value": "33OMUKMKSKU80UPRY5NM"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 30 "wait": 30
} }
} }
In the preceding example, the AS includes the continue field in the In the preceding example, the AS includes the continue field in the
response. Therefore, the client instance can continue the grant response. Therefore, the client instance can continue the grant
negotiation process, perhaps modifying the request as discussed in negotiation process, perhaps modifying the request as discussed in
Section 5.3. Section 5.3.
5.2. Continuing During Pending Interaction (Polling) 5.2. Continuing during Pending Interaction (Polling)
When the client instance does not include a finish parameter, the When the client instance does not include a finish parameter, the
client instance will often need to poll the AS until the RO has client instance will often need to poll the AS until the RO has
authorized the request. To do so, the client instance makes a POST authorized the request. To do so, the client instance makes a POST
request to the continuation URI as in Section 5.1, but does not request to the continuation URI as in Section 5.1 but does not
include message content. include message content.
POST /continue HTTP/1.1 POST /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
If the grant request is in the _approved_ state, the grant response If the grant request is in the _approved_ state, the grant response
(Section 3) MAY contain any newly-created access tokens (Section 3.2) (Section 3) MAY contain any newly created access tokens (Section 3.2)
or newly-released subject claims (Section 3.4). The response MAY or newly released subject claims (Section 3.4). The response MAY
contain a new "continue" response (Section 3.1) as described above. contain a new continuation response (Section 3.1) as described above.
If a continue field is included, it SHOULD include a wait field to If a continue field is included, it SHOULD include a wait field to
facilitate a reasonable polling rate by the client instance. The facilitate a reasonable polling rate by the client instance. The
response SHOULD NOT contain interaction responses (Section 3.3). response SHOULD NOT contain interaction responses (Section 3.3).
If the grant request is in the _pending_ state, the grant response If the grant request is in the _pending_ state, the grant response
(Section 3) MUST NOT contain access tokens or subject information, (Section 3) MUST NOT contain access tokens or subject information and
and MAY contain a new interaction responses (Section 3.3) to any MAY contain a new interaction response (Section 3.3) to any
interaction methods that have not been exhausted at the AS. interaction methods that have not been exhausted at the AS.
For example, if the request has not yet been authorized by the RO, For example, if the request has not yet been authorized by the RO,
the AS could respond by telling the client instance to make another the AS could respond by telling the client instance to make another
continuation request in the future. In the following non-normative continuation request in the future. In the following non-normative
example, a new, unique access token has been issued for the call, example, a new, unique access token has been issued for the call,
which the client instance will use in its next continuation request. which the client instance will use in its next continuation request.
{ {
"continue": { "continue": {
skipping to change at page 93, line 39 skipping to change at line 4196
} }
}, },
"subject": { "subject": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
} ] } ]
} }
} }
See Section 13.23 for considerations on polling for continuation See Section 11.23 for considerations on polling for continuation
without an interaction finish method. without an interaction finish method.
In error conditions, the AS responds to the client instance with the In error conditions, the AS responds to the client instance with an
error code as discussed in Section 3.6. For example, if the client error code as discussed in Section 3.6. For example, if the client
instance has polled too many times before the RO has approved the instance has polled too many times before the RO has approved the
request, the AS would respond with a message like the following: request, the AS would respond with a message like the following:
{ {
"error": "too_many_attempts" "error": "too_many_attempts"
} }
Since this response does not include a continue section, the client
Since this response does not include a continue field, the client
instance cannot continue to poll the AS for additional updates and instance cannot continue to poll the AS for additional updates and
the grant request is _finalized_. If the client instance still needs the grant request is _finalized_. If the client instance still needs
access to the resource, it will need to start with a new grant access to the resource, it will need to start with a new grant
request. request.
5.3. Modifying an Existing Request 5.3. Modifying an Existing Request
The client instance might need to modify an ongoing request, whether The client instance might need to modify an ongoing request, whether
or not tokens have already been issued or subject information has or not tokens have already been issued or subject information has
already been released. In such cases, the client instance makes an already been released. In such cases, the client instance makes an
skipping to change at page 94, line 27 skipping to change at line 4231
considered unchanged from the original request. considered unchanged from the original request.
A grant request associated with a modification request MUST be in the A grant request associated with a modification request MUST be in the
_approved_ or _pending_ state. When the AS receives a valid _approved_ or _pending_ state. When the AS receives a valid
modification request, the AS MUST place the grant request into the modification request, the AS MUST place the grant request into the
_processing_ state and re-evaluate the authorization in the new _processing_ state and re-evaluate the authorization in the new
context created by the update request, since the extent and context context created by the update request, since the extent and context
of the request could have changed. of the request could have changed.
The client instance MAY include the access_token and subject fields The client instance MAY include the access_token and subject fields
as described in Section 2.1 and Section 2.2. Inclusion of these as described in Sections 2.1 and 2.2. Inclusion of these fields
fields override any values in the initial request, which MAY trigger override any values in the initial request, which MAY trigger
additional requirements and policies by the AS. For example, if the additional requirements and policies by the AS. For example, if the
client instance is asking for more access, the AS could require client instance is asking for more access, the AS could require
additional interaction with the RO to gather additional consent. If additional interaction with the RO to gather additional consent. If
the client instance is asking for more limited access, the AS could the client instance is asking for more limited access, the AS could
determine that sufficient authorization has been granted to the determine that sufficient authorization has been granted to the
client instance and return the more limited access rights client instance and return the more limited access rights
immediately. If the grant request was previously in the _approved_ immediately. If the grant request was previously in the _approved_
state, the AS could decide to remember the larger scale of access state, the AS could decide to remember the larger scale of access
rights associated with the grant request, allowing the client rights associated with the grant request, allowing the client
instance to make subsequent requests of different subsets of granted instance to make subsequent requests of different subsets of granted
access. The details of this processing are out of scope for this access. The details of this processing are out of scope for this
specification, but a one possible approach is as follows: specification, but a one possible approach is as follows:
1. A client instance requests access to Foo, and is granted by the 1. A client instance requests access to Foo, and this is granted by
RO. This results in an access token, AT1. the RO. This results in an access token: AT1.
2. The client instance later modifies the grant request to include 2. The client instance later modifies the grant request to include
Foo and Bar together. Since the client instance was previously Foo and Bar together. Since the client instance was previously
granted Foo under this grant request, the RO is prompted to allow granted Foo under this grant request, the RO is prompted to allow
the client instance access to Foo and Bar together. This results the client instance access to Foo and Bar together. This results
in a new access token, AT2 This access token has access to both in a new access token: AT2. This access token has access to both
Foo and Bar. The rights of the original access token AT1 are not Foo and Bar. The rights of the original access token AT1 are not
modified. modified.
3. The client instance makes another grant modification to ask only 3. The client instance makes another grant modification to ask only
for Bar. Since the client instance was previously granted Foo and for Bar. Since the client instance was previously granted Foo and
Bar together under this grant request, the RO is not prompted and Bar together under this grant request, the RO is not prompted,
the access to Bar is granted in a new access token, AT3. This and the access to Bar is granted in a new access token: AT3.
new access token does not allow access to Foo. This new access token does not allow access to Foo.
4. The original access token AT1 expires and the client seeks a new 4. The original access token AT1 expires, and the client seeks a new
access token to replace it. The client instance makes another access token to replace it. The client instance makes another
grant modification to ask only for Foo. Since the client instance grant modification to ask only for Foo. Since the client instance
was previously granted Foo and Bar together under this grant was previously granted Foo and Bar together under this grant
request, the RO is not prompted and the access to Foo is granted request, the RO is not prompted, and the access to Foo is granted
in a new access token, AT4. This new access token does not allow in a new access token: AT4. This new access token does not allow
access to Bar. access to Bar.
All four access tokens are independent of each other and associated All four access tokens are independent of each other and associated
with the same underlying grant request. Each of these access tokens with the same underlying grant request. Each of these access tokens
could possibly also be rotated using token management, if available. could possibly also be rotated using token management, if available.
For example, instead of asking for a new token to replace AT1, the For example, instead of asking for a new token to replace AT1, the
client instance could ask for a refresh of AT1 using the rotation client instance could ask for a refresh of AT1 using the rotation
method of the token management API. This would result in a refreshed method of the token management API. This would result in a refreshed
AT1 with a different token value and expiration from the original AT1 AT1 with a different token value and expiration from the original AT1
but with the same access rights of allowing only access to Foo. but with the same access rights of allowing only access to Foo.
skipping to change at page 95, line 41 skipping to change at line 4293
this field replaces any values from a previous request. The AS MAY this field replaces any values from a previous request. The AS MAY
respond to any of the interaction responses as described in respond to any of the interaction responses as described in
Section 3.3, just like it would to a new request. Section 3.3, just like it would to a new request.
The client instance MAY include the user field as described in The client instance MAY include the user field as described in
Section 2.4 to present new assertions or information about the end Section 2.4 to present new assertions or information about the end
user. The AS SHOULD check that this presented user information is user. The AS SHOULD check that this presented user information is
consistent with any user information previously presented by the consistent with any user information previously presented by the
client instance or otherwise associated with this grant request. client instance or otherwise associated with this grant request.
The client instance MUST NOT include the client section of the The client instance MUST NOT include the client field of the request,
request, since the client instance is assumed not to have changed. since the client instance is assumed not to have changed.
Modification of client instance information, including rotation of Modification of client instance information, including rotation of
keys associated with the client instance, is outside the scope of keys associated with the client instance, is outside the scope of
this specification. this specification.
The client instance MUST NOT include post-interaction responses such The client instance MUST NOT include post-interaction responses such
as described in Section 5.1. as those described in Section 5.1.
Modification requests MUST NOT alter previously-issued access tokens. Modification requests MUST NOT alter previously issued access tokens.
Instead, any access tokens issued from a continuation are considered Instead, any access tokens issued from a continuation are considered
new, separate access tokens. The AS MAY revoke previously-issued new, separate access tokens. The AS MAY revoke previously issued
access tokens after a modification has occurred. access tokens after a modification has occurred.
If the modified request can be granted immediately by the AS (the If the modified request can be granted immediately by the AS (the
grant request is in the _approved_ state), the grant response grant request is in the _approved_ state), the grant response
(Section 3) MAY contain any newly-created access tokens (Section 3.2) (Section 3) MAY contain any newly created access tokens (Section 3.2)
or newly-released subject claims (Section 3.4). The response MAY or newly released subject claims (Section 3.4). The response MAY
contain a new "continue" response (Section 3.1) as described above. contain a new continuation response (Section 3.1) as described above.
If interaction can occur, the response SHOULD contain interaction If interaction can occur, the response SHOULD contain interaction
responses (Section 3.3) as well. responses (Section 3.3) as well.
For example, a client instance initially requests a set of resources For example, a client instance initially requests a set of resources
using references: using references:
POST /tx HTTP/1.1 POST /tx HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Signature-Input: sig1=... Signature-Input: sig1=...
skipping to change at page 97, line 45 skipping to change at line 4386
{ {
"access_token": { "access_token": {
"access": [ "access": [
"read" "read"
] ]
} }
... ...
} }
The AS replaces the previous access from the first request, allowing The AS replaces the previous access from the first request, allowing
the AS to determine if any previously-granted consent already the AS to determine if any previously granted consent already
applies. In this case, the AS would determine that reducing the applies. In this case, the AS would determine that reducing the
breadth of the requested access means that new access tokens can be breadth of the requested access means that new access tokens can be
issued to the client instance without additional interaction or issued to the client instance without additional interaction or
consent. The AS would likely revoke previously-issued access tokens consent. The AS would likely revoke previously issued access tokens
that had the greater access rights associated with them, unless they that had the greater access rights associated with them, unless they
had been issued with the durable flag. had been issued with the durable flag.
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "M33OMUK80UPRY5NMKSKU" "value": "M33OMUK80UPRY5NMKSKU"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 30 "wait": 30
}, },
"access_token": { "access_token": {
"value": "0EVKC7-2ZKwZM_6N760", "value": "0EVKC7-2ZKwZM_6N760",
"access": [ "access": [
"read" "read"
] ]
} }
} }
For another example, the client instance initially requests read-only As another example, the client instance initially requests read-only
access but later needs to step up its access. The initial request access but later needs to step up its access. The initial request
could look like the following HTTP message. could look like the following HTTP message:
POST /tx HTTP/1.1 POST /tx HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Content-Digest: sha-256=... Content-Digest: sha-256=...
{ {
"access_token": { "access_token": {
skipping to change at page 99, line 25 skipping to change at line 4461
"access": [ "access": [
"read" "read"
] ]
} }
} }
This allows the client instance to make an eventual continuation This allows the client instance to make an eventual continuation
call. The client instance later realizes that it now needs "write" call. The client instance later realizes that it now needs "write"
access in addition to the "read" access. Since this is an expansion access in addition to the "read" access. Since this is an expansion
of what it asked for previously, the client instance also includes a of what it asked for previously, the client instance also includes a
new interaction section in case the AS needs to interact with the RO new interaction field in case the AS needs to interact with the RO
again to gather additional authorization. Note that the client again to gather additional authorization. Note that the client
instance's nonce and callback are different from the initial request. instance's nonce and callback are different from the initial request.
Since the original callback was already used in the initial exchange, Since the original callback was already used in the initial exchange
and the callback is intended for one-time-use, a new one needs to be and the callback is intended for one-time use, a new one needs to be
included in order to use the callback again. included in order to use the callback again.
PATCH /continue HTTP/1.1 PATCH /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Content-Digest: sha-256=... Content-Digest: sha-256=...
skipping to change at page 101, line 5 skipping to change at line 4515
place it into the _finalized_ state, the client instance makes an place it into the _finalized_ state, the client instance makes an
HTTP DELETE request to the continuation URI. HTTP DELETE request to the continuation URI.
DELETE /continue HTTP/1.1 DELETE /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
If the request is successfully revoked, the AS responds with status If the request is successfully revoked, the AS responds with HTTP
code HTTP 204 (No Content). The AS SHOULD revoke all associated status code 204 (No Content). The AS SHOULD revoke all associated
access tokens, if possible. The AS SHOULD disable all token rotation access tokens, if possible. The AS SHOULD disable all token rotation
and other token management functions on such access tokens, if and other token management functions on such access tokens, if
possible. Once the grant request is in the _finalized_ state, it possible. Once the grant request is in the _finalized_ state, it
MUST NOT be moved to any other state. MUST NOT be moved to any other state.
If the request is not revoked, the AS responds with an If the request is not revoked, the AS responds with an
invalid_continuation error (Section 3.6). invalid_continuation error (Section 3.6).
6. Token Management 6. Token Management
If an access token response includes the manage field as described in If an access token response includes the manage field as described in
Section 3.2.1, the client instance MAY call this URI to manage the Section 3.2.1, the client instance MAY call this URI to manage the
access token with the rotate and revoke actions defined in the access token with the rotate and revoke actions defined in the
following sections. Other actions are undefined by this following subsections. Other actions are undefined by this
specification. specification.
{ {
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"flags": ["bearer"], "flags": ["bearer"],
"manage": { "manage": {
"uri": "https://server.example.com/token/PRY5NM33O", "uri": "https://server.example.com/token/PRY5NM33O",
"access_token": { "access_token": {
"value": "B8CDFONP21-4TB8N6.BW7ONM" "value": "B8CDFONP21-4TB8N6.BW7ONM"
} }
} }
} }
} }
The token management access token issued under the manage field is The token management access token issued under the manage field is
used to protect all calls to the token management API. The client used to protect all calls to the token management API. The client
instance MUST present proof of the key associated with the token instance MUST present proof of the key associated with the token
along with the token management access token value. along with the value of the token management access token.
The AS MUST validate the proof and ensure that it is associated with The AS MUST validate the proof and ensure that it is associated with
the token management access token. the token management access token.
The AS MUST uniquely identify the token being managed from the token The AS MUST uniquely identify the token being managed from the token
management URI, the token management access token, or a combination management URI, the token management access token, or a combination
of both. of both.
6.1. Rotating the Access Token Value 6.1. Rotating the Access Token Value
skipping to change at page 102, line 26 skipping to change at line 4579
token in the authorization header as described in Section 7.2 and token in the authorization header as described in Section 7.2 and
signing the request with the appropriate key. signing the request with the appropriate key.
POST /token/PRY5NM33O HTTP/1.1 POST /token/PRY5NM33O HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP B8CDFONP21-4TB8N6.BW7ONM Authorization: GNAP B8CDFONP21-4TB8N6.BW7ONM
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Content-Digest: sha-256=... Content-Digest: sha-256=...
The client instance can not request to alter the access rights The client instance cannot request to alter the access rights
associated with the access token during a rotation request. To get associated with the access token during a rotation request. To get
an access token with different access rights for this grant request, an access token with different access rights for this grant request,
the client instance has to call the continuation API's update the client instance has to call the continuation API's update
(Section 5.3) functionality to get a new access token. The client functionality (Section 5.3) to get a new access token. The client
instance can also create a new grant request with the required access instance can also create a new grant request with the required access
rights. rights.
The AS validates that the token management access token presented is The AS validates that the token management access token presented is
associated with the management URI, that the AS issued the token to associated with the management URI, that the AS issued the token to
the given client instance, and that the presented key is the correct the given client instance, and that the presented key is the correct
key for the token management access token. The AS determines which key for the token management access token. The AS determines which
access token is being rotated from the token management URI, the access token is being rotated from the token management URI, the
token management access token, or both. token management access token, or both.
If the token is validated and the key is appropriate for the request, If the token is validated and the key is appropriate for the request,
the AS MUST invalidate the current access token value associated with the AS MUST invalidate the current access token value associated with
this URI, if possible. Note that stateless access tokens can make this URI, if possible. Note that stateless access tokens can make
proactive revocation difficult within a system, see Section 13.32. proactive revocation difficult within a system; see Section 11.32.
For successful rotations, the AS responds with an HTTP 200 with a For successful rotations, the AS responds with an HTTP status code
JSON-formatted message content consisting of the rotated access token 200 (OK) with JSON-formatted message content consisting of the
in the access_token field described in Section 3.2.1. The value of rotated access token in the access_token field described in
the access token MUST NOT be the same as the current value of the Section 3.2.1. The value of the access token MUST NOT be the same as
access token used to access the management API. The response MUST the current value of the access token used to access the management
include an access token management URI, and the value of this URI MAY API. The response MUST include an access token management URI, and
be different from the URI used by the client instance to make the the value of this URI MAY be different from the URI used by the
rotation call. The client instance MUST use this new URI to manage client instance to make the rotation call. The client instance MUST
the rotated access token. use this new URI to manage the rotated access token.
The access rights in the access array for the rotated access token The access rights in the access array for the rotated access token
MUST be included in the response and MUST be the same as the token MUST be included in the response and MUST be the same as the token
before rotation. before rotation.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
{ {
"access_token": { "access_token": {
"value": "FP6A8H6HY37MH13CK76LBZ6Y1UADG6VEUPEER5H2", "value": "FP6A8H6HY37MH13CK76LBZ6Y1UADG6VEUPEER5H2",
skipping to change at page 104, line 4 skipping to change at line 4646
], ],
"datatypes": [ "datatypes": [
"metadata", "metadata",
"images" "images"
] ]
}, },
"read", "dolphin-metadata" "read", "dolphin-metadata"
] ]
} }
} }
If the AS is unable or unwilling to rotate the value of the access If the AS is unable or unwilling to rotate the value of the access
token, the AS responds with an invalid_rotation error (Section 3.6). token, the AS responds with an invalid_rotation error (Section 3.6).
Upon receiving such an error, the client instance MUST consider the Upon receiving such an error, the client instance MUST consider the
access token to not have changed its state. access token to not have changed its state.
6.1.1. Binding a New Key to the Rotated Access Token 6.1.1. Binding a New Key to the Rotated Access Token
If the client instance wishes to bind a new presentation key to an If the client instance wishes to bind a new presentation key to an
access token, the client instance MUST present both the new key and access token, the client instance MUST present both the new key and
the proof of previous key material in the access token rotation the proof of previous key material in the access token rotation
request. The client instance makes an HTTP POST as a JSON object request. The client instance makes an HTTP POST as a JSON object
with the following field: with the following field:
key: The new key value or reference in the format described in key: The new key value or reference in the format described in
Section 7.1. Note that keys passed by value are always public Section 7.1. Note that keys passed by value are always public
keys. REQUIRED when doing key rotation. keys. REQUIRED when doing key rotation.
The proof method and parameters for the new key MUST be the same as The proofing method and parameters for the new key MUST be the same
those established for the previous key. as those established for the previous key.
The client instance MUST prove possession of both the currently-bound The client instance MUST prove possession of both the currently bound
key and the newly-requested key simultaneously in the rotation key and the newly requested key simultaneously in the rotation
request. Specifically, the signature from the previous key MUST request. Specifically, the signature from the previous key MUST
cover the value or reference of the new key, and the signature of the cover the value or reference of the new key, and the signature of the
new key MUST cover the signature value of the old key. The means of new key MUST cover the signature value of the old key. The means of
doing so varies depending on the proofing method in use. For doing so vary depending on the proofing method in use. For example,
example, the HTTP Message Signatures proofing method uses multiple the HTTP message signatures proofing method uses multiple signatures
signatures in the request as described in Section 7.3.1.1, as shown in the request as described in Section 7.3.1.1. This is shown in the
in this example. following example.
POST /token/PRY5NM33O HTTP/1.1 POST /token/PRY5NM33O HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP B8CDFONP21-4TB8N6.BW7ONM Authorization: GNAP B8CDFONP21-4TB8N6.BW7ONM
Signature-Input: \ Signature-Input: \
sig1=("@method" "@target-uri" "content-digest" \ sig1=("@method" "@target-uri" "content-digest" \
"authorization"),\ "authorization"),\
sig2=("@method" "@target-uri" "content-digest" \ sig2=("@method" "@target-uri" "content-digest" \
"authorization" "signature";key="sig1" \ "authorization" "signature";key="sig1" \
"signature-input";key="sig1") "signature-input";key="sig1")
skipping to change at page 105, line 31 skipping to change at line 4703
"kty": "RSA", "kty": "RSA",
"e": "AQAB", "e": "AQAB",
"kid": "xyz-2", "kid": "xyz-2",
"alg": "RS256", "alg": "RS256",
"n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8xY..." "n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8xY..."
} }
} }
} }
Failure to present the appropriate proof of either the new key or the Failure to present the appropriate proof of either the new key or the
previous key for the access token, as defined by the proof method, previous key for the access token, as defined by the proofing method,
MUST result in an invalid_rotation error code from the AS MUST result in an invalid_rotation error code from the AS
(Section 3.6). (Section 3.6).
An attempt to change the proof method or parameters, including an An attempt to change the proofing method or parameters, including an
attempt to rotate the key of a bearer token (which has no key), MUST attempt to rotate the key of a bearer token (which has no key), MUST
result in an invalid_rotation error code returned from the AS result in an invalid_rotation error code returned from the AS
(Section 3.6). (Section 3.6).
If the AS does not allow rotation of the access token's key for any If the AS does not allow rotation of the access token's key for any
reason, including but not limited to lack of permission for this reason, including but not limited to lack of permission for this
client instance or lack of capability by the AS, the AS MUST return a client instance or lack of capability by the AS, the AS MUST return a
key_rotation_not_supported error code (Section 3.6). key_rotation_not_supported error code (Section 3.6).
6.2. Revoking the Access Token 6.2. Revoking the Access Token
skipping to change at page 106, line 17 skipping to change at line 4738
with the appropriate key. with the appropriate key.
DELETE /token/PRY5NM33O HTTP/1.1 DELETE /token/PRY5NM33O HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP B8CDFONP21-4TB8N6.BW7ONM Authorization: GNAP B8CDFONP21-4TB8N6.BW7ONM
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
If the key presented is associated with the token (or the client If the key presented is associated with the token (or the client
instance, in the case of a bearer token), the AS MUST invalidate the instance, in the case of a bearer token), the AS MUST invalidate the
access token, if possible, and return an HTTP 204 response code. access token, if possible, and return an HTTP response code 204.
204 No Content 204 No Content
Though the AS MAY revoke an access token at any time for any reason, Though the AS MAY revoke an access token at any time for any reason,
the token management function is specifically for the client the token management function is specifically for the client
instance's use. If the access token has already expired or has been instance's use. If the access token has already expired or has been
revoked through other means, the AS SHOULD honor the revocation revoked through other means, the AS SHOULD honor the revocation
request to the token management URI as valid, since the end result is request to the token management URI as valid, since the end result is
still the token not being usable. that the token is still not usable.
7. Securing Requests from the Client Instance 7. Securing Requests from the Client Instance
In GNAP, the client instance secures its requests to an AS and RS by In GNAP, the client instance secures its requests to an AS and RS by
presenting an access token, presenting proof of a key that it presenting an access token, proof of a key that it possesses (aka, a
possesses (aka, a "key proof"), or both an access token and key proof "key proof"), or both an access token and key proof together.
together.
* When an access token is used with a key proof, this is a bound * When an access token is used with a key proof, this is a bound
token request. This type of request is used for calls to the RS token request. This type of request is used for calls to the RS
as well as the AS during grant negotiation. as well as the AS during grant negotiation.
* When a key proof is used with no access token, this is a non- * When a key proof is used with no access token, this is a non-
authorized signed request. This type of request is used for calls authorized signed request. This type of request is used for calls
to the AS to initiate a grant negotiation. to the AS to initiate a grant negotiation.
* When an access token is used with no key proof, this is a bearer * When an access token is used with no key proof, this is a bearer
token request. This type of request is used only for calls to the token request. This type of request is used only for calls to the
RS, and only with access tokens that are not bound to any key as RS and only with access tokens that are not bound to any key as
described in Section 3.2.1. described in Section 3.2.1.
* When neither an access token nor key proof are used, this is an * When neither an access token nor key proof are used, this is an
unsecured request. This type of request is used optionally for unsecured request. This type of request is used optionally for
calls to the RS as part of an RS-first discovery process as calls to the RS as part of an RS-first discovery process as
described in Section 9.1. described in Section 9.1.
7.1. Key Formats 7.1. Key Formats
Several different places in GNAP require the presentation of key Several different places in GNAP require the presentation of key
skipping to change at page 107, line 22 skipping to change at line 4790
All keys are associated with a specific key proofing method. The All keys are associated with a specific key proofing method. The
proofing method associated with the key is indicated using the proof proofing method associated with the key is indicated using the proof
field of the key object. field of the key object.
proof (string or object): The form of proof that the client instance proof (string or object): The form of proof that the client instance
will use when presenting the key. The valid values of this field will use when presenting the key. The valid values of this field
and the processing requirements for each are detailed in and the processing requirements for each are detailed in
Section 7.3. REQUIRED. Section 7.3. REQUIRED.
A key presented by value MUST be a public key and MUST be presented A key presented by value MUST be a public key and MUST be presented
in one and only one supported format, as discussed in Section 13.35. in only one supported format, as discussed in Section 11.35. Note
Note that while most formats present the full value of the public that while most formats present the full value of the public key,
key, some formats present a value cryptographically derived from the some formats present a value cryptographically derived from the
public key. See additional discussion of the presentation of public public key. See additional discussion of the presentation of public
keys in Section 13.7. keys in Section 11.7.
jwk (object): The public key and its properties represented as a jwk (object): The public key and its properties represented as a
JSON Web Key [RFC7517]. A JWK MUST contain the alg (Algorithm) JSON Web Key (JWK) [RFC7517]. A JWK MUST contain the alg
and kid (Key ID) parameters. The alg parameter MUST NOT be (Algorithm) and kid (Key ID) parameters. The alg parameter MUST
"none". The x5c (X.509 Certificate Chain) parameter MAY be used NOT be "none". The x5c (X.509 Certificate Chain) parameter MAY be
to provide the X.509 representation of the provided public key. used to provide the X.509 representation of the provided public
OPTIONAL. key. OPTIONAL.
cert (string): PEM serialized value of the certificate used to sign cert (string): The Privacy-Enhanced Mail (PEM) serialized value of
the request, with optional internal whitespace per [RFC7468]. The the certificate used to sign the request, with optional internal
PEM header and footer are optionally removed. OPTIONAL. whitespace per [RFC7468]. The PEM header and footer are
optionally removed. OPTIONAL.
cert#S256 (string): The certificate thumbprint calculated as per cert#S256 (string): The certificate thumbprint calculated as per
OAuth-MTLS [RFC8705] in base64 URL encoding. Note that this MTLS for OAuth [RFC8705] in base64url encoding. Note that this
format does not include the full public key. OPTIONAL. format does not include the full public key. OPTIONAL.
Additional key formats are defined in the GNAP Key Formats Registry Additional key formats can be defined in the "GNAP Key Formats"
(Section 11.17). registry (Section 10.17).
The following non-normative example shows a single key presented in The following non-normative example shows a single key presented in
two different formats. The example key is intended to be used with two different formats. The example key is intended to be used with
the HTTP Message Signatures (Section 7.3.1) proofing mechanism, as the HTTP message signatures proofing mechanism (Section 7.3.1), as
indicated by the httpsig value of the proof field. indicated by the httpsig value of the proof field.
As a JSON Web Key: As a JWK:
"key": { "key": {
"proof": "httpsig", "proof": "httpsig",
"jwk": { "jwk": {
"kty": "RSA", "kty": "RSA",
"e": "AQAB", "e": "AQAB",
"kid": "xyz-1", "kid": "xyz-1",
"alg": "RS256", "alg": "RS256",
"n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8xY..." "n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8xY..."
} }
skipping to change at page 108, line 25 skipping to change at line 4842
As a certificate in PEM format: As a certificate in PEM format:
"key": { "key": {
"proof": "httpsig", "proof": "httpsig",
"cert": "MIIEHDCCAwSgAwIBAgIBATANBgkqhkiG9w0BAQsFA..." "cert": "MIIEHDCCAwSgAwIBAgIBATANBgkqhkiG9w0BAQsFA..."
} }
When the key is presented in GNAP, proof of this key material MUST be When the key is presented in GNAP, proof of this key material MUST be
used to bind the request, the nature of which varies with the used to bind the request, the nature of which varies with the
location in the protocol the key is used. For a key used as part of location in the protocol where the key is used. For a key used as
a client instance's initial request in Section 2.3, the key value part of a client instance's initial request in Section 2.3, the key
represents the client instance's public key, and proof of that key value represents the client instance's public key, and proof of that
MUST be presented in that request. For a key used as part of an key MUST be presented in that request. For a key used as part of an
access token response in Section 3.2.1, the proof of that key MUST be access token response in Section 3.2.1, the proof of that key MUST be
used when the client instance later presents the access token to the used when the client instance later presents the access token to the
RS. RS.
7.1.1. Key References 7.1.1. Key References
Keys in GNAP can also be passed by reference such that the party Keys in GNAP can also be passed by reference such that the party
receiving the reference will be able to determine the appropriate receiving the reference will be able to determine the appropriate
keying material for use in that part of the protocol. Key references keying material for use in that part of the protocol. A key
are a single opaque string. reference is a single opaque string.
"key": "S-P4XJQ_RYJCRTSU1.63N3E" "key": "S-P4XJQ_RYJCRTSU1.63N3E"
Keys referenced in this manner MAY be shared symmetric keys. See the Keys referenced in this manner MAY be shared symmetric keys. See the
additional considerations for symmetric keys in Section 13.7. The additional considerations for symmetric keys in Section 11.7. The
key reference MUST NOT contain any unencrypted private or shared key reference MUST NOT contain any unencrypted private or shared
symmetric key information. symmetric key information.
Keys referenced in this manner MUST be bound to a single proofing Keys referenced in this manner MUST be bound to a single proofing
mechanism. mechanism.
The means of dereferencing this reference to a key value and proofing The means of dereferencing this reference to a key value and proofing
mechanism are out of scope for this specification. Commonly, key mechanism are out of scope for this specification. Commonly, key
references are created by the AS and are not necessarily needed to be references are created by the AS and do not necessarily need to be
understood by the client. These types of key references are an understood by the client. These types of key references are an
internal reference to the AS, such as an identifier of a record in a internal reference to the AS, such as an identifier of a record in a
database. In other applications, it can be useful to use key database. In other applications, it can be useful to use key
references that are resolvable by both clients and AS, which could be references that are resolvable by both clients and the AS, which
accomplished by a client publishing a public key at a URI, for could be accomplished by a client publishing a public key at a URI,
example. For interoperability, this method could later be described for example. For interoperability, this method could later be
as an extension, but doing so is out of scope for this specification. described as an extension, but doing so is out of scope for this
specification.
7.1.2. Key Protection 7.1.2. Key Protection
The security of GNAP relies on the cryptographic security of the keys The security of GNAP relies on the cryptographic security of the keys
themselves. When symmetric keys are used in GNAP, a key management themselves. When symmetric keys are used in GNAP, a key management
system or secure key derivation mechanism MUST be used to supply the system or secure key derivation mechanism MUST be used to supply the
keys. Symmetric keys MUST NOT be a human memorable password or a keys. Symmetric keys MUST NOT be a human-memorable password or a
value derived from one. Symmetric keys MUST NOT be passed by value value derived from one. Symmetric keys MUST NOT be passed by value
from the client instance to the AS. from the client instance to the AS.
Additional security considerations apply when rotating keys Additional security considerations apply when rotating keys (see
(Section 13.22). Section 11.22).
7.2. Presenting Access Tokens 7.2. Presenting Access Tokens
Access tokens are issued to client instances in GNAP to allow the Access tokens are issued to client instances in GNAP to allow the
client instance to make an authorized call to an API. The method the client instance to make an authorized call to an API. The method the
client instance uses to send an access token depends on whether the client instance uses to send an access token depends on whether the
token is bound to a key, and if so which proofing method is token is bound to a key and, if so, which proofing method is
associated with the key. This information is conveyed by the key associated with the key. This information is conveyed by the key
parameter and the bearer flag in the access token response structure parameter and the bearer flag in the access token response structure
(Section 3.2.1). (Section 3.2.1).
If the flags field does not contain the bearer flag and the key is If the flags field does not contain the bearer flag and the key is
absent, the access token MUST be sent using the same key and proofing absent, the access token MUST be sent using the same key and proofing
mechanism that the client instance used in its initial request (or mechanism that the client instance used in its initial request (or
its most recent rotation). its most recent rotation).
If the flags field does not contain the bearer flag and the key value If the flags field does not contain the bearer flag and the key value
is an object as described in Section 7.1, the access token MUST be is an object as described in Section 7.1, the access token MUST be
sent using the key and proofing mechanism defined by the value of the sent using the key and proofing mechanism defined by the value of the
proof field within the key object. proof field within the key object.
The access token MUST be sent using the HTTP "Authorization" request The access token MUST be sent using the HTTP Authorization request
header field and the "GNAP" authorization scheme along with a key header field and the "GNAP" authorization scheme along with a key
proof as described in Section 7.3 for the key bound to the access proof as described in Section 7.3 for the key bound to the access
token. For example, an access token bound using HTTP Message token. For example, an access token bound using HTTP message
Signatures would be sent as follows: signatures would be sent as follows:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
GET /stuff HTTP/1.1 GET /stuff HTTP/1.1
Host: resource.example.com Host: resource.example.com
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=("@method" "@target-uri" "authorization")\ Signature-Input: sig1=("@method" "@target-uri" "authorization")\
;created=1618884473;keyid="gnap-rsa";nonce="NAOEJF12ER2";tag="gnap" ;created=1618884473;keyid="gnap-rsa";nonce="NAOEJF12ER2";tag="gnap"
Signature: sig1=:FQ+EjWqc38uLFByKa5y+c4WyYYwCTGUhidWKfr5L1Cha8FiPEw\ Signature: sig1=:FQ+EjWqc38uLFByKa5y+c4WyYYwCTGUhidWKfr5L1Cha8FiPEw\
DxG7nWttpBLS/B6VLfkZJogPbclySs9MDIsAIJwHnzlcJjwXWR2lfvm2z3X7EkJHm\ DxG7nWttpBLS/B6VLfkZJogPbclySs9MDIsAIJwHnzlcJjwXWR2lfvm2z3X7EkJHm\
Zp4SmyKOS34luAiKR1xwf32NYFolHmZf/SbHZJuWvQuS4U33C+BbsXz8MflFH1Dht\ Zp4SmyKOS34luAiKR1xwf32NYFolHmZf/SbHZJuWvQuS4U33C+BbsXz8MflFH1Dht\
H/C1E5i244gSbdLCPxzABc/Q0NHVSLo1qaouYIvnxXB8OT3K7mwWjsLh1GC5vFThb\ H/C1E5i244gSbdLCPxzABc/Q0NHVSLo1qaouYIvnxXB8OT3K7mwWjsLh1GC5vFThb\
3XQ363r6f0OPRa4qWHhubR/d/J/lNOjbBdjq9AJ69oqNJ+A2XT+ZCrVasEJE0OBvD\ 3XQ363r6f0OPRa4qWHhubR/d/J/lNOjbBdjq9AJ69oqNJ+A2XT+ZCrVasEJE0OBvD\
auQoiywhb8BMB7+PEINsPk5/8UvaNxbw==: auQoiywhb8BMB7+PEINsPk5/8UvaNxbw==:
If the flags field contains the bearer flag, the access token is a If the flags field contains the bearer flag, the access token is a
bearer token that MUST be sent using the Authorization Request Header bearer token that MUST be sent using the Authorization request header
Field method defined in [RFC6750]. field method defined in [RFC6750].
Authorization: Bearer OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0 Authorization: Bearer OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0
The Form-Encoded Body Parameter and URI Query Parameter methods of The Form-Encoded Body Parameter and URI Query Parameter methods of
[RFC6750] MUST NOT be used for GNAP access tokens. [RFC6750] MUST NOT be used for GNAP access tokens.
7.3. Proving Possession of a Key with a Request 7.3. Proving Possession of a Key with a Request
Any keys presented by the client instance to the AS or RS MUST be Any keys presented by the client instance to the AS or RS MUST be
validated as part of the request in which they are presented. The validated as part of the request in which they are presented. The
type of binding used is indicated by the proof parameter of the key type of binding used is indicated by the proof parameter of the key
object in Section 7.1. Key proof methods are specified either by a object in Section 7.1. Key proofing methods are specified either by
string, which consists of the key proof method name on its own, or by a string, which consists of the key proofing method name on its own,
a JSON object with the required field method: or by a JSON object with the required field method:
method: The name of the key proofing method to be used. REQUIRED. method: The name of the key proofing method to be used. REQUIRED.
Individual methods defined as objects MAY define additional Individual methods defined as objects MAY define additional
parameters as members in this object. parameters as members in this object.
Values for the method defined by this specification are as follows: Values for the method defined by this specification are as follows:
"httpsig" (string or object): HTTP Signing signature headers. See "httpsig" (string or object): HTTP message signing. See
Section 7.3.1. Section 7.3.1.
"mtls" (string): Mutual TLS certificate verification. See "mtls" (string): MTLS certificate verification. See Section 7.3.2.
Section 7.3.2.
"jwsd" (string): A detached JWS signature header. See "jwsd" (string): A detached JWS signature header. See
Section 7.3.3. Section 7.3.3.
"jws" (string): Attached JWS payload. See Section 7.3.4. "jws" (string): Attached JWS Payload. See Section 7.3.4.
Additional proofing methods are defined by the GNAP Key Proofing Additional proofing methods can be defined in the "GNAP Key Proofing
Methods Registry (Section 11.16). Methods" registry (Section 10.16).
Proof methods MAY be defined as both an object and a string. For Proofing methods MAY be defined as both an object and a string. For
example, the httpsig method can be specified as an object with its example, the httpsig method can be specified as an object with its
parameters explicitly declared, such as: parameters explicitly declared, such as:
{ {
"proof": { "proof": {
"method": "httpsig", "method": "httpsig",
"alg": "ecdsa-p384-sha384", "alg": "ecdsa-p384-sha384",
"content-digest-alg": "sha-256" "content-digest-alg": "sha-256"
} }
} }
skipping to change at page 111, line 40 skipping to change at line 4999
} }
All key binding methods used by this specification MUST cover all All key binding methods used by this specification MUST cover all
relevant portions of the request, including anything that would relevant portions of the request, including anything that would
change the nature of the request, to allow for secure validation of change the nature of the request, to allow for secure validation of
the request. Relevant aspects include the URI being called, the HTTP the request. Relevant aspects include the URI being called, the HTTP
method being used, any relevant HTTP headers and values, and the HTTP method being used, any relevant HTTP headers and values, and the HTTP
message content itself. The verifier of the signed message MUST message content itself. The verifier of the signed message MUST
validate all components of the signed message to ensure that nothing validate all components of the signed message to ensure that nothing
has been tampered with or substituted in a way that would change the has been tampered with or substituted in a way that would change the
nature of the request. Key binding method definitions MUST enumerate nature of the request. Definitions of key binding methods MUST
how these requirements are fulfilled. enumerate how these requirements are fulfilled.
When a key proofing mechanism is bound to an access token, the key When a key proofing mechanism is bound to an access token, the key
being presented MUST be the key associated with the access token and being presented MUST be the key associated with the access token, and
the access token MUST be covered by the signature method of the the access token MUST be covered by the signature method of the
proofing mechanism. proofing mechanism.
The key binding methods in this section MAY be used by other The key binding methods in this section MAY be used by other
components making calls as part of GNAP, such as the extensions components making calls as part of GNAP, such as the extensions
allowing the RS to make calls to the AS defined in allowing the RS to make calls to the AS defined in [GNAP-RS]. To
[I-D.ietf-gnap-resource-servers]. To facilitate this extended use, facilitate this extended use, "signer" and "verifier" are used as
the sections below are defined in generic terms of the "signer" and generic terms in the subsections below. In the core functions of
"verifier" of the HTTP message. In the core functions of GNAP GNAP specified in this document, the "signer" is the client instance,
specified in this document, the "signer" is the client instance and and the "verifier" is the AS (for grant requests) or RS (for resource
the "verifier" is the AS (for grant requests) or RS (for resource
requests), as appropriate. requests), as appropriate.
When used for delegation in GNAP, these key binding mechanisms allow When used for delegation in GNAP, these key binding mechanisms allow
the AS to ensure that the keys presented by the client instance in the AS to ensure that the keys presented by the client instance in
the initial request are in control of the party calling any follow-up the initial request are in control of the party calling any follow-up
or continuation requests. To facilitate this requirement, the or continuation requests. To facilitate this requirement, the
continuation response (Section 3.1) includes an access token bound to continuation response (Section 3.1) includes an access token bound to
the client instance's key (Section 2.3), and that key (or its most the client instance's key (Section 2.3), and that key (or its most
recent rotation) MUST be proved in all continuation requests recent rotation) MUST be proved in all continuation requests
(Section 5). Token management requests (Section 6) are similarly (Section 5). Token management requests (Section 6) are similarly
bound to either the access token's own key or, in the case of bearer bound to either the access token's own key or, in the case of bearer
tokens, the client instance's key. tokens, the client instance's key.
In the following sections, unless otherwise noted, the RS256 JOSE In the following subsections, unless otherwise noted, the RS256 JSON
Signature Algorithm (defined in Section 3.3 of [RFC7518]) is applied Object Signing and Encryption (JOSE) signature algorithm (defined in
using the following RSA key (presented here in JWK format): Section 3.3 of [RFC7518]) is applied using the following RSA key
(presented here in JWK format):
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
{ {
"kid": "gnap-rsa", "kid": "gnap-rsa",
"p": "xS4-YbQ0SgrsmcA7xDzZKuVNxJe3pCYwdAe6efSy4hdDgF9-vhC5gjaRk\ "p": "xS4-YbQ0SgrsmcA7xDzZKuVNxJe3pCYwdAe6efSy4hdDgF9-vhC5gjaRk\
i1wWuERSMW4Tv44l5HNrL-Bbj_nCJxr_HAOaesDiPn2PnywwEfg3Nv95Nn-\ i1wWuERSMW4Tv44l5HNrL-Bbj_nCJxr_HAOaesDiPn2PnywwEfg3Nv95Nn-\
eilhqXRaW-tJKEMjDHu_fmJBeemHNZI412gBnXdGzDVo22dvYoxd6GM", eilhqXRaW-tJKEMjDHu_fmJBeemHNZI412gBnXdGzDVo22dvYoxd6GM",
"kty": "RSA", "kty": "RSA",
"q": "rVdcT_uy-CD0GKVLGpEGRR7k4JO6Tktc8MEHkC6NIFXihk_6vAIOCzCD6\ "q": "rVdcT_uy-CD0GKVLGpEGRR7k4JO6Tktc8MEHkC6NIFXihk_6vAIOCzCD6\
skipping to change at page 113, line 48 skipping to change at line 5075
zywzwPTuq-cVQDyEN7aL0SxCb3Hc4IdqDaMg8qHUyObpPitDQ" zywzwPTuq-cVQDyEN7aL0SxCb3Hc4IdqDaMg8qHUyObpPitDQ"
} }
Key proofing methods SHOULD define a mechanism to allow the rotation Key proofing methods SHOULD define a mechanism to allow the rotation
of keys discussed in Section 6.1.1. Key rotation mechanisms MUST of keys discussed in Section 6.1.1. Key rotation mechanisms MUST
define a way for presenting proof of two keys simultaneously with the define a way for presenting proof of two keys simultaneously with the
following attributes: following attributes:
* The value of or reference to the new key material MUST be signed * The value of or reference to the new key material MUST be signed
by the existing key. Generally speaking, this amounts to using by the existing key. Generally speaking, this amounts to using
the existing key to sign the content of the message which contains the existing key to sign the content of the message that contains
the new key. the new key.
* The signature of the old key MUST be signed by the new key. * The signature of the old key MUST be signed by the new key.
Generally speaking, this means including the signature value of Generally speaking, this means including the signature value of
the old key under the coverage of the new key. the old key under the coverage of the new key.
7.3.1. HTTP Message Signatures 7.3.1. HTTP Message Signatures
This method is indicated by the method value httpsig and can be This method is indicated by the method value httpsig and can be
declared in either object form or string form. declared in either object form or string form.
When the proof method is specified in object form, the following When the proofing method is specified in object form, the following
parameters are defined: parameters are defined:
alg: The HTTP signature algorithm, from the HTTP Signature Algorithm alg: The HTTP signature algorithm, from the "HTTP Signature
registry. REQUIRED. Algorithms" registry. REQUIRED.
content-digest-alg: The algorithm used for the Content-Digest field, content-digest-alg: The algorithm used for the Content-Digest field,
used to protect the content when present in the message. used to protect the content when present in the message.
REQUIRED. REQUIRED.
This example uses the ECDSA signing algorithm over the P384 curve and This example uses the Elliptic Curve Digital Signature Algorithm
the SHA-512 hashing algorithm for the content digest. (ECDSA) signing algorithm over the P384 curve and the SHA-512 hashing
algorithm for the content digest.
{ {
"proof": { "proof": {
"method": "httpsig", "method": "httpsig",
"alg": "ecdsa-p384-sha384", "alg": "ecdsa-p384-sha384",
"content-digest-alg": "sha-512" "content-digest-alg": "sha-512"
} }
} }
When the proof method is specified in string form, the signing When the proofing method is specified in string form, the signing
algorithm MUST be derived from the key material (such as using the algorithm MUST be derived from the key material (such as using the
JWS algorithm in a JWK formatted key), and the content digest JWS algorithm in a JWK formatted key), and the content digest
algorithm MUST be sha-256. algorithm MUST be sha-256.
{ {
"proof": "httpsig" "proof": "httpsig"
} }
When using this method, the signer creates an HTTP Message Signature When using this method, the signer creates an HTTP message signature
as described in [RFC9421]. The covered components of the signature as described in [RFC9421]. The covered components of the signature
MUST include the following: MUST include the following:
"@method": The method used in the HTTP request. "@method": The method used in the HTTP request.
"@target-uri": The full request URI of the HTTP request. "@target-uri": The full request URI of the HTTP request.
When the message contains request content, the covered components When the message contains request content, the covered components
MUST also include the following: MUST also include the following:
skipping to change at page 115, line 34 skipping to change at line 5155
this value. The signer MUST include the created signature parameter this value. The signer MUST include the created signature parameter
with a timestamp of when the signature was created, and the verifier with a timestamp of when the signature was created, and the verifier
MUST ensure that the creation timestamp is sufficiently close to the MUST ensure that the creation timestamp is sufficiently close to the
current time given expected network delay and clock skew. The signer current time given expected network delay and clock skew. The signer
SHOULD include the nonce parameter with a unique and unguessable SHOULD include the nonce parameter with a unique and unguessable
value. When included, the verifier MUST determine that the nonce value. When included, the verifier MUST determine that the nonce
value is unique within a reasonably short time period such as several value is unique within a reasonably short time period such as several
minutes. minutes.
If the signer's key presented is a JWK, the keyid parameter of the If the signer's key presented is a JWK, the keyid parameter of the
signature MUST be set to the kid value of the JWK, the signing signature MUST be set to the kid value of the JWK, and the signing
algorithm used MUST be the JWS algorithm denoted by the key's alg algorithm used MUST be the JWS algorithm denoted by the key's alg
field of the JWK. field of the JWK.
The explicit alg signature parameter MUST NOT be included in the The explicit alg signature parameter MUST NOT be included in the
signature, since the algorithm will be derived either from the key signature, since the algorithm will be derived from either the key
material or from the proof value. material or the proof value.
In the following non-normative example, the message content is the In the following non-normative example, the message content is a JSON
following JSON object: object:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
{ {
"access_token": { "access_token": {
"access": [ "access": [
"dolphin-metadata" "dolphin-metadata"
] ]
}, },
"interact": { "interact": {
skipping to change at page 118, line 26 skipping to change at line 5283
} }
} }
"display": { "display": {
"name": "My Client Display Name", "name": "My Client Display Name",
"uri": "https://client.foo/" "uri": "https://client.foo/"
}, },
} }
} }
The verifier MUST ensure that the signature covers all required The verifier MUST ensure that the signature covers all required
message components. If the HTTP Message includes content, the message components. If the HTTP message includes content, the
verifier MUST calculate and verify the value of the Content-Digest verifier MUST calculate and verify the value of the Content-Digest
header. The verifier MUST validate the signature against the header. The verifier MUST validate the signature against the
expected key of the signer. expected key of the signer.
A received message MAY include multiple signatures, each with its own A received message MAY include multiple signatures, each with its own
label. The verifier MUST examine all included signatures until it label. The verifier MUST examine all included signatures until it
finds (at least) one that's acceptable according to its policy and finds (at least) one that is acceptable according to its policy and
meets the requirements in this section. meets the requirements in this section.
7.3.1.1. Key Rotation using HTTP Message Signatures 7.3.1.1. Key Rotation Using HTTP Message Signatures
When rotating a key using HTTP Message Signatures, the message, which When rotating a key using HTTP message signatures, the message, which
includes the new public key value or reference, is first signed with includes the new public key value or reference, is first signed with
the old key following all of the requirements in Section 7.3.1. The the old key following all of the requirements in Section 7.3.1. The
message is then signed again with the new key by following all of the message is then signed again with the new key by following all of the
requirements in Section 7.3.1 again with the following additional requirements in Section 7.3.1 again, with the following additional
requirements: requirements:
* The covered components MUST include the Signature and Signature- * The covered components MUST include the Signature and Signature-
Input values from the signature generated with the old key Input values from the signature generated with the old key.
* The tag value MUST be gnap-rotate.
* The tag value MUST be gnap-rotate
For example, the following request to the token management endpoint For example, the following request to the token management endpoint
for rotating a token value contains the new key in the request. The for rotating a token value contains the new key in the request. The
message is first signed using the old key and the resulting signature message is first signed using the old key, and the resulting
is placed in "old-key": signature is placed in "old-key":
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
POST /token/PRY5NM33 HTTP/1.1 POST /token/PRY5NM33 HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP 4398.34-12-asvDa.a Authorization: GNAP 4398.34-12-asvDa.a
Content-Digest: sha-512=:Fb/A5vnawhuuJ5xk2RjGrbbxr6cvinZqd4+JPY85u/\ Content-Digest: sha-512=:Fb/A5vnawhuuJ5xk2RjGrbbxr6cvinZqd4+JPY85u/\
JNyTlmRmCOtyVhZ1Oz/cSS4tsYen6fzpCwizy6UQxNBQ==: JNyTlmRmCOtyVhZ1Oz/cSS4tsYen6fzpCwizy6UQxNBQ==:
Signature-Input: old-key=("@method" "@target-uri" "content-digest" \ Signature-Input: old-key=("@method" "@target-uri" "content-digest" \
"authorization");created=1618884475;keyid="test-key-ecc-p256"\ "authorization");created=1618884475;keyid="test-key-ecc-p256"\
skipping to change at page 123, line 32 skipping to change at line 5482
"name": "My Client Display Name", "name": "My Client Display Name",
"uri": "https://client.foo/" "uri": "https://client.foo/"
}, },
}, },
"subject": { "subject": {
"formats": ["iss_sub", "opaque"] "formats": ["iss_sub", "opaque"]
} }
} }
The verifier compares the TLS client certificate presented during The verifier compares the TLS client certificate presented during
mutual TLS negotiation to the expected key of the signer. Since the MTLS negotiation to the expected key of the signer. Since the TLS
TLS connection covers the entire message, there are no additional connection covers the entire message, there are no additional
requirements to check. requirements to check.
Note that in many instances, the verifier will not do a full Note that in many instances, the verifier will not do a full
certificate chain validation of the presented TLS client certificate, certificate chain validation of the presented TLS client certificate,
as the means of trust for this certificate could be in something as the means of trust for this certificate could be in something
other than a PKI system, such as a static registration or trust-on- other than a PKI system, such as a static registration or trust-on-
first-use. See Section 13.3 and Section 13.4 for some additional first-use. See Sections 11.3 and 11.4 for some additional
considerations for this key proofing method. considerations for this key proofing method.
7.3.2.1. Key Rotation using MTLS 7.3.2.1. Key Rotation Using MTLS
Since it is not possible to present two client authenticated Since it is not possible to present two client authenticated
certificates to a mutual TLS connection simultaneously, dynamic key certificates to a MTLS connection simultaneously, dynamic key
rotation for this proofing method is not defined. Instead, key rotation for this proofing method is not defined. Instead, key
rotation for MTLS-based client instances is expected to be managed rotation for MTLS-based client instances is expected to be managed
through deployment practices, as discussed in Section 13.4. through deployment practices, as discussed in Section 11.4.
7.3.3. Detached JWS 7.3.3. Detached JWS
This method is indicated by the method value jwsd in string form. This method is indicated by the method value jwsd in string form.
{ {
"proof": "jwsd" "proof": "jwsd"
} }
The signer creates a JSON Web Signature (JWS) [RFC7515] object as The signer creates a JSON Web Signature (JWS) [RFC7515] object as
follows: follows.
To protect the request, the JOSE header of the signature contains the To protect the request, the JOSE header of the signature contains the
following claims: following claims:
kid (string): The key identifier. REQUIRED if the key is presented kid (string): The key identifier. REQUIRED if the key is presented
in JWK format, this MUST be the value of the kid field of the key. in JWK format. This MUST be the value of the kid field of the
key.
alg (string): The algorithm used to sign the request. MUST be alg (string): The algorithm used to sign the request. The algorithm
appropriate to the key presented. If the key is presented as a MUST be appropriate to the key presented. If the key is presented
JWK, this MUST be equal to the alg parameter of the key. MUST NOT as a JWK, this MUST be equal to the alg parameter of the key. The
be none. REQUIRED. algorithm MUST NOT be none. REQUIRED.
typ (string): The type header, value "gnap-binding-jwsd". REQUIRED. typ (string): The type header, value "gnap-binding-jwsd". REQUIRED.
htm (string): The HTTP Method used to make this request, as a case- htm (string): The HTTP method used to make this request, as a case-
sensitive ASCII string. Note that most public HTTP methods are in sensitive ASCII string. Note that most public HTTP methods are in
uppercase ASCII by convention. REQUIRED. uppercase ASCII by convention. REQUIRED.
uri (string): The HTTP URI used for this request. This value MUST uri (string): The HTTP URI used for this request. This value MUST
be an absolute URI, including all path and query components and no be an absolute URI, including all path and query components and no
fragment component. REQUIRED. fragment components. REQUIRED.
created (integer): A timestamp of when the signature was created, in created (integer): A timestamp of when the signature was created, in
integer seconds since UNIX Epoch. REQUIRED. integer seconds since UNIX Epoch. REQUIRED.
When the request is bound to an access token, the JOSE header MUST When the request is bound to an access token, the JOSE header MUST
also include the following: also include the following:
ath (string): The hash of the access token. The value MUST be the ath (string): The hash of the access token. The value MUST be the
result of Base64url encoding (with no padding) the SHA-256 digest result of base64url encoding (with no padding) the SHA-256 digest
of the ASCII encoding of the associated access token's value. of the ASCII encoding of the associated access token's value.
REQUIRED. REQUIRED.
If the HTTP request has content, such as an HTTP POST or PUT method, If the HTTP request has content (such as an HTTP POST or PUT method),
the payload of the JWS object is the Base64url encoding (without the payload of the JWS object is the base64url encoding (without
padding) of the SHA256 digest of the bytes of the content. If the padding) of the SHA-256 digest of the bytes of the content. If the
request being made does not have content, such as an HTTP GET, request being made does not have content (such as an HTTP GET,
OPTIONS, or DELETE method, the JWS signature is calculated over an OPTIONS, or DELETE method), the JWS signature is calculated over an
empty payload. empty payload.
The signer presents the signed object in compact form [RFC7515] in The signer presents the signed object in compact form [RFC7515] in
the Detached-JWS HTTP Header field. the Detached-JWS header field.
In the following non-normative example, the JOSE Header contains the In the following non-normative example, the JOSE header contains the
following parameters: following parameters:
{ {
"alg": "RS256", "alg": "RS256",
"kid": "gnap-rsa", "kid": "gnap-rsa",
"uri": "https://server.example.com/gnap", "uri": "https://server.example.com/gnap",
"htm": "POST", "htm": "POST",
"typ": "gnap-binding-jwsd", "typ": "gnap-binding-jwsd",
"created": 1618884475 "created": 1618884475
} }
skipping to change at page 126, line 44 skipping to change at line 5608
N7aL0SxCb3Hc4IdqDaMg8qHUyObpPitDQ" N7aL0SxCb3Hc4IdqDaMg8qHUyObpPitDQ"
} }
} }
"display": { "display": {
"name": "My Client Display Name", "name": "My Client Display Name",
"uri": "https://client.foo/" "uri": "https://client.foo/"
}, },
} }
} }
This is hashed to the following Base64 encoded value: This is hashed to the following base64-encoded value:
PGiVuOZUcN1tRtUS6tx2b4cBgw9mPgXG3IPB3wY7ctc PGiVuOZUcN1tRtUS6tx2b4cBgw9mPgXG3IPB3wY7ctc
This leads to the following full HTTP request message: This leads to the following full HTTP request message:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
POST /gnap HTTP/1.1 POST /gnap HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
skipping to change at page 128, line 15 skipping to change at line 5672
"uri": "https://client.foo/" "uri": "https://client.foo/"
}, },
} }
} }
When the verifier receives the Detached-JWS header, it MUST parse and When the verifier receives the Detached-JWS header, it MUST parse and
validate the JWS object. The signature MUST be validated against the validate the JWS object. The signature MUST be validated against the
expected key of the signer. If the HTTP message request contains expected key of the signer. If the HTTP message request contains
content, the verifier MUST calculate the hash of the content just as content, the verifier MUST calculate the hash of the content just as
the signer does, with no normalization or transformation of the the signer does, with no normalization or transformation of the
request. All required fields MUST be present and their values MUST request. All required fields MUST be present, and their values MUST
be valid. All fields MUST match the corresponding portions of the be valid. All fields MUST match the corresponding portions of the
HTTP message. For example, the htm field of the JWS header has to be HTTP message. For example, the htm field of the JWS header has to be
the same as the HTTP verb used in the request. the same as the HTTP verb used in the request.
Note that this proof method depends on a specific cryptographic Note that this proofing method depends on a specific cryptographic
algorithm, SHA-256, in two ways: the ath hash algorithm is hardcoded, algorithm, SHA-256, in two ways: 1) the ath hash algorithm is
and computing the payload of the detached/attached signature also hardcoded and 2) the payload of the detached/attached signature is
uses a hardcoded hash. A future version of this document may address computed using a hardcoded hash. A future version of this document
crypto-agility for both these uses by replacing ath with a new header may address crypto-agility for both these uses by replacing ath with
that upgrades the algorithm, and possibly defining a new JWS header a new header that upgrades the algorithm and possibly defining a new
that indicates the HTTP content's hash method. JWS header that indicates the HTTP content's hash method.
7.3.3.1. Key Rotation using Detached JWS 7.3.3.1. Key Rotation Using Detached JWS
When rotating a key using Detached JWS, the message, which includes When rotating a key using detached JWS, the message, which includes
the new public key value or reference, is first signed with the old the new public key value or reference, is first signed with the old
key as described above using a JWS object with typ header value key as described above using a JWS object with typ header value
"gnap-binding-rotation-jwsd". The value of the JWS object is then "gnap-binding-rotation-jwsd". The value of the JWS object is then
taken as the payload of a new JWS object, to be signed by the new key taken as the payload of a new JWS object, to be signed by the new key
using the parameters above. using the parameters above.
The value of the new JWS object is sent in the Detached-JWS header. The value of the new JWS object is sent in the Detached-JWS header.
7.3.4. Attached JWS 7.3.4. Attached JWS
This method is indicated by the method value jws in string form. This method is indicated by the method value jws in string form.
{ {
"proof": "jws" "proof": "jws"
} }
The signer creates a JWS [RFC7515] object as follows: The signer creates a JWS [RFC7515] object as follows.
To protect the request, the JWS header contains the following claims. To protect the request, the JWS header contains the following claims:
kid (string): The key identifier. REQUIRED if the key is presented kid (string): The key identifier. REQUIRED if the key is presented
in JWK format, this MUST be the value of the kid field of the key. in JWK format. This MUST be the value of the kid field of the
key.
alg (string): The algorithm used to sign the request. MUST be alg (string): The algorithm used to sign the request. MUST be
appropriate to the key presented. If the key is presented as a appropriate to the key presented. If the key is presented as a
JWK, this MUST be equal to the alg parameter of the key. MUST NOT JWK, this MUST be equal to the alg parameter of the key. MUST NOT
be none. REQUIRED. be none. REQUIRED.
typ (string): The type header, value "gnap-binding-jws". REQUIRED. typ (string): The type header, value "gnap-binding-jws". REQUIRED.
htm (string): The HTTP Method used to make this request, as a case- htm (string): The HTTP method used to make this request, as a case-
sensitive ASCII string. (Note that most public HTTP methods are sensitive ASCII string. (Note that most public HTTP methods are
in uppercase.) REQUIRED. in uppercase.) REQUIRED.
uri (string): The HTTP URI used for this request, including all path uri (string): The HTTP URI used for this request, including all path
and query components and no fragment component. REQUIRED. and query components and no fragment components. REQUIRED.
created (integer): A timestamp of when the signature was created, in created (integer): A timestamp of when the signature was created, in
integer seconds since UNIX Epoch. REQUIRED. integer seconds since UNIX Epoch. REQUIRED.
When the request is bound to an access token, the JOSE header MUST When the request is bound to an access token, the JOSE header MUST
also include the following: also include the following:
ath (string): The hash of the access token. The value MUST be the ath (string): The hash of the access token. The value MUST be the
result of Base64url encoding (with no padding) the SHA-256 digest result of base64url encoding (with no padding) the SHA-256 digest
of the ASCII encoding of the associated access token's value. of the ASCII encoding of the associated access token's value.
REQUIRED. REQUIRED.
If the HTTP request has content, such as an HTTP POST or PUT method, If the HTTP request has content (such as an HTTP POST or PUT method),
the payload of the JWS object is the JSON serialized content of the the payload of the JWS object is the JSON serialized content of the
request, and the object is signed according to JWS and serialized request, and the object is signed according to JWS and serialized
into compact form [RFC7515]. The signer presents the JWS as the into compact form [RFC7515]. The signer presents the JWS as the
content of the request along with a content type of application/jose. content of the request along with a content type of application/jose.
The verifier MUST extract the payload of the JWS and treat it as the The verifier MUST extract the payload of the JWS and treat it as the
request content for further processing. request content for further processing.
If the request being made does not have content, such as an HTTP GET, If the request being made does not have content (such as an HTTP GET,
OPTIONS, or DELETE method, the JWS signature is calculated over an OPTIONS, or DELETE method), the JWS signature is calculated over an
empty payload and passed in the Detached-JWS header as described in empty payload and passed in the Detached-JWS header as described in
Section 7.3.3. Section 7.3.3.
In the following non-normative example, the JOSE header contains the In the following non-normative example, the JOSE header contains the
following parameters: following parameters:
{ {
"alg": "RS256", "alg": "RS256",
"kid": "gnap-rsa", "kid": "gnap-rsa",
"uri": "https://server.example.com/gnap", "uri": "https://server.example.com/gnap",
skipping to change at page 132, line 44 skipping to change at line 5848
AogICAgfSwKICAgICJzdWJqZWN0IjogewogICAgICAgICJmb3JtYXRzIjogWyJpc3Nf\ AogICAgfSwKICAgICJzdWJqZWN0IjogewogICAgICAgICJmb3JtYXRzIjogWyJpc3Nf\
c3ViIiwgIm9wYXF1ZSJdCiAgICB9Cn0K.MwNoVMQp5hVxI0mCs9LlOUdFtkDXaA1_eT\ c3ViIiwgIm9wYXF1ZSJdCiAgICB9Cn0K.MwNoVMQp5hVxI0mCs9LlOUdFtkDXaA1_eT\
vOXq7DOGrtDKH7q4vP2xUq3fH2jRAZqnobo0WdPP3eM3NH5QUjW8pa6_QpwdIWkK7r-\ vOXq7DOGrtDKH7q4vP2xUq3fH2jRAZqnobo0WdPP3eM3NH5QUjW8pa6_QpwdIWkK7r-\
u_52puE0lPBp7J4U2w4l9gIbg8iknsmWmXeY5F6wiGT8ptfuEYGgmloAJd9LIeNvD3U\ u_52puE0lPBp7J4U2w4l9gIbg8iknsmWmXeY5F6wiGT8ptfuEYGgmloAJd9LIeNvD3U\
LW2h2dz1Pn2eDnbyvgB0Ugae0BoZB4f69fKWj8Z9wvTIjk1LZJN1PcL7_zT8Lrlic9a\ LW2h2dz1Pn2eDnbyvgB0Ugae0BoZB4f69fKWj8Z9wvTIjk1LZJN1PcL7_zT8Lrlic9a\
PyzT7Q9ovkd1s-4whE7TrnGUzFc5mgWUn_gsOpsP5mIIljoEEv-FqOW2RyNYulOZl0Q\ PyzT7Q9ovkd1s-4whE7TrnGUzFc5mgWUn_gsOpsP5mIIljoEEv-FqOW2RyNYulOZl0Q\
8EnnDHV_vPzrHlUarbGg4YffgtwkQhdK72-JOxYQ 8EnnDHV_vPzrHlUarbGg4YffgtwkQhdK72-JOxYQ
When the verifier receives an attached JWS request, it MUST parse and When the verifier receives an attached JWS request, it MUST parse and
validate the JWS object. The signature MUST be validated against the validate the JWS object. The signature MUST be validated against the
expected key of the signer. All required fields MUST be present and expected key of the signer. All required fields MUST be present, and
their values MUST be valid. All fields MUST match the corresponding their values MUST be valid. All fields MUST match the corresponding
portions of the HTTP message. For example, the htm field of the JWS portions of the HTTP message. For example, the htm field of the JWS
header has to be the same as the HTTP verb used in the request. header has to be the same as the HTTP verb used in the request.
Note that this proof method depends on a specific cryptographic Note that this proofing method depends on a specific cryptographic
algorithm, SHA-256, in two ways: the ath hash algorithm is hardcoded, algorithm, SHA-256, in two ways: the ath hash algorithm is hardcoded,
and computing the payload of the detached/attached signature also and computing the payload of the detached/attached signature also
uses a hardcoded hash. A future version of this document may address uses a hardcoded hash. A future version of this document may address
crypto-agility for both these uses by replacing ath with a new header crypto-agility for both these uses by replacing ath with a new header
that upgrades the algorithm, and possibly defining a new header that that upgrades the algorithm and possibly defining a new header that
indicates the HTTP content's hash method. indicates the HTTP content's hash method.
7.3.4.1. Key Rotation using Attached JWS 7.3.4.1. Key Rotation Using Attached JWS
When rotating a key using Attached JWS, the message, which includes When rotating a key using attached JWS, the message, which includes
the new public key value or reference, is first signed with the old the new public key value or reference, is first signed with the old
key using a JWS object with typ header value "gnap-binding-rotation- key using a JWS object with typ header value "gnap-binding-rotation-
jws". The value of the JWS object is then taken as the payload of a jws". The value of the JWS object is then taken as the payload of a
new JWS object, to be signed by the new key. new JWS object, to be signed by the new key.
8. Resource Access Rights 8. Resource Access Rights
GNAP provides a rich structure for describing the protected resources GNAP provides a rich structure for describing the protected resources
hosted by RSs and accessed by client software. This structure is hosted by RSs and accessed by client software. This structure is
used when the client instance requests an access token (Section 2.1) used when the client instance requests an access token (Section 2.1)
and when an access token is returned (Section 3.2). GNAP's structure and when an access token is returned (Section 3.2). GNAP's structure
is designed to be analogous to the OAuth 2.0 Rich Authorization is designed to be analogous to the OAuth 2.0 Rich Authorization
Request data structure defined in [RFC9396]. Requests data structure defined in [RFC9396].
The root of this structure is a JSON array. The elements of the JSON The root of this structure is a JSON array. The elements of the JSON
array represent rights of access that are associated with the access array represent rights of access that are associated with the access
token. Individual rights of access can be defined by the RS as token. Individual rights of access can be defined by the RS as
either an object or a string. The resulting access is the union of either an object or a string. The resulting access is the union of
all elements within the array. all elements within the array.
The access associated with the access token is described using The access associated with the access token is described using
objects that each contain multiple dimensions of access. Each object objects that each contain multiple dimensions of access. Each object
contains a REQUIRED type property that determines the type of API contains a REQUIRED type property that determines the type of API
skipping to change at page 134, line 15 skipping to change at line 5914
While it is expected that many APIs will have their own properties, While it is expected that many APIs will have their own properties,
this specification defines a set of common data fields that are this specification defines a set of common data fields that are
designed to be usable across different types of APIs. This designed to be usable across different types of APIs. This
specification does not require the use of these common fields by an specification does not require the use of these common fields by an
API definition but, instead, provides them as reusable generic API definition but, instead, provides them as reusable generic
components for API designers to make use of. The allowable values of components for API designers to make use of. The allowable values of
all fields are determined by the API being protected, as defined by a all fields are determined by the API being protected, as defined by a
particular type value. particular type value.
actions (array of strings): The types of actions the client instance actions (array of strings): The types of actions the client instance
will take at the RS as an array of strings. For example, a client will take at the RS as an array of strings (for example, a client
instance asking for a combination of "read" and "write" access. instance asking for a combination of "read" and "write" access).
locations (array of strings): The location of the RS as an array of locations (array of strings): The location of the RS as an array of
strings. These strings are typically URIs identifying the strings. These strings are typically URIs identifying the
location of the RS. location of the RS.
datatypes (array of strings): The kinds of data available to the datatypes (array of strings): The kinds of data available to the
client instance at the RS's API as an array of strings. For client instance at the RS's API as an array of strings (for
example, a client instance asking for access to raw "image" data example, a client instance asking for access to raw "image" data
and "metadata" at a photograph API. and "metadata" at a photograph API).
identifier (string): A string identifier indicating a specific identifier (string): A string identifier indicating a specific
resource at the RS. For example, a patient identifier for a resource at the RS (for example, a patient identifier for a
medical API or a bank account number for a financial API. medical API or a bank account number for a financial API).
privileges (array of strings): The types or levels of privilege privileges (array of strings): The types or levels of privilege
being requested at the resource. For example, a client instance being requested at the resource (for example, a client instance
asking for administrative level access, or access when the asking for administrative-level access or access when the RO is no
resource owner is no longer online. longer online).
The following non-normative example is describing three kinds of The following non-normative example describes three kinds of access
access (read, write, delete) to each of two different locations and (read, write, and delete) to each of two different locations and two
two different data types (metadata, images) for a single access token different data types (metadata and images) for a single access token
using the fictitious photo-api type definition. using the fictitious photo-api type definition.
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read", "read",
"write", "write",
"delete" "delete"
], ],
skipping to change at page 135, line 25 skipping to change at line 5960
"https://resource.local/other" "https://resource.local/other"
], ],
"datatypes": [ "datatypes": [
"metadata", "metadata",
"images" "images"
] ]
} }
] ]
While the exact semantics of interpreting the fields of an access While the exact semantics of interpreting the fields of an access
request object is subject to the definition of the type, it is request object are subject to the definition of the type, it is
expected that the access requested for each object in the array is expected that the access requested for each object in the array is
the cross-product of all fields of the object. That is to say, the the cross-product of all fields of the object. That is to say, the
object represents a request for all actions listed to be used at all object represents a request for all actions listed to be used at all
locations listed for all possible datatypes listed within the object. locations listed for all possible datatypes listed within the object.
Assuming the request above was granted, the client instance could Assuming the request above was granted, the client instance could
assume that it would be able to do a read action against the images assume that it would be able to do a read action against the images
on the first server as well as a delete action on the metadata of the on the first server as well as a delete action on the metadata of the
second server, or any other combination of these fields, using the second server, or any other combination of these fields, using the
same access token. same access token.
To request a different combination of access, such as requesting one To request a different combination of access, such as requesting one
of the possible actions against one of the possible locations and a of the possible actions against one of the possible locations and a
different choice of possible actions against a different one of the different choice of possible actions against a different one of the
possible locations, the client instance can include multiple separate possible locations, the client instance can include multiple separate
objects in the resources array. The total access rights for the objects in the resources array. The total access rights for the
resulting access token is the union of all objects. The following resulting access token are the union of all objects. The following
non-normative example uses the same fictitious photo-api type non-normative example uses the same fictitious photo-api type
definition to request a single access token with more specifically definition to request a single access token with more specifically
targeted access rights by using two discrete objects within the targeted access rights by using two discrete objects within the
request. request.
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read" "read"
skipping to change at page 136, line 34 skipping to change at line 6011
"locations": [ "locations": [
"https://resource.local/other" "https://resource.local/other"
], ],
"datatypes": [ "datatypes": [
"metadata" "metadata"
] ]
} }
] ]
The access requested here is for read access to images on one server The access requested here is for read access to images on one server
while simultaneously requesting write and delete access for metadata as well as write and delete access for metadata on a different server
on a different server, but importantly without requesting write or (importantly, without requesting write or delete access to images on
delete access to images on the first server. the first server).
It is anticipated that API designers will use a combination of common It is anticipated that API designers will use a combination of common
fields defined in this specification as well as fields specific to fields defined in this specification as well as fields specific to
the API itself. The following non-normative example shows the use of the API itself. The following non-normative example shows the use of
both common and API-specific fields as part of two different both common and API-specific fields as part of two different
fictitious API type values. The first access request includes the fictitious API type values. The first access request includes the
actions, locations, and datatypes fields specified here as well as actions, locations, and datatypes fields specified here as well as
the API-specific geolocation field. The second access request the API-specific geolocation field. The second access request
includes the actions and identifier fields specified here as well as includes the actions and identifier fields specified here as well as
the API-specific currency field. the API-specific currency field.
skipping to change at page 137, line 39 skipping to change at line 6059
], ],
"identifier": "account-14-32-32-3", "identifier": "account-14-32-32-3",
"currency": "USD" "currency": "USD"
} }
] ]
If this request is approved, the resulting access token's access If this request is approved, the resulting access token's access
rights will be the union of the requested types of access for each of rights will be the union of the requested types of access for each of
the two APIs, just as above. the two APIs, just as above.
8.1. Requesting Resources By Reference 8.1. Requesting Resources by Reference
Instead of sending an object describing the requested resource Instead of sending an object describing the requested resource
(Section 8), access rights MAY be communicated as a string known to (Section 8), access rights MAY be communicated as a string known to
the AS representing the access being requested. Just like access the AS representing the access being requested. Just like access
rights communicated as an object, access rights communicated as rights communicated as an object, access rights communicated as
reference strings indicate a specific access at a protected resource. reference strings indicate a specific access at a protected resource.
In the following non-normative example, three distinct resource In the following non-normative example, three distinct resource
access rights are being requested. access rights are being requested.
"access": [ "access": [
skipping to change at page 138, line 4 skipping to change at line 6072
(Section 8), access rights MAY be communicated as a string known to (Section 8), access rights MAY be communicated as a string known to
the AS representing the access being requested. Just like access the AS representing the access being requested. Just like access
rights communicated as an object, access rights communicated as rights communicated as an object, access rights communicated as
reference strings indicate a specific access at a protected resource. reference strings indicate a specific access at a protected resource.
In the following non-normative example, three distinct resource In the following non-normative example, three distinct resource
access rights are being requested. access rights are being requested.
"access": [ "access": [
"read", "dolphin-metadata", "some other thing" "read", "dolphin-metadata", "some other thing"
] ]
This value is opaque to the client instance and MAY be any valid JSON This value is opaque to the client instance and MAY be any valid JSON
string, and therefore could include spaces, unicode characters, and string; therefore, it could include spaces, Unicode characters, and
properly escaped string sequences. However, in some situations the properly escaped string sequences. However, in some situations, the
value is intended to be seen and understood by the client software's value is intended to be seen and understood by the client software's
developer. In such cases, the API designer choosing any such human- developer. In such cases, the API designer choosing any such human-
readable strings SHOULD take steps to ensure the string values are readable strings SHOULD take steps to ensure the string values are
not easily confused by a developer, such as by limiting the strings not easily confused by a developer, such as by limiting the strings
to easily disambiguated characters. to easily disambiguated characters.
This functionality is similar in practice to OAuth 2.0's scope This functionality is similar in practice to OAuth 2.0's scope
parameter [RFC6749], where a single string represents the set of parameter [RFC6749], where a single string represents the set of
access rights requested by the client instance. As such, the access rights requested by the client instance. As such, the
reference string could contain any valid OAuth 2.0 scope value as in reference string could contain any valid OAuth 2.0 scope value, as in
Appendix C.5. Note that the reference string here is not bound to Appendix B.5. Note that the reference string here is not bound to
the same character restrictions as in OAuth 2.0's scope definition. the same character restrictions as OAuth 2.0's scope definition.
A single access array MAY include both object-type and string-type A single access array MAY include both object-type and string-type
resource items. In this non-normative example, the client instance resource items. In this non-normative example, the client instance
is requesting access to a photo-api and financial-transaction API is requesting access to a photo-api and financial-transaction API
type as well as the reference values of read, dolphin-metadata, and type as well as the reference values of read, dolphin-metadata, and
some other thing. some other thing.
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
skipping to change at page 139, line 42 skipping to change at line 6132
"some other thing" "some other thing"
] ]
The requested access is the union of all elements of the array, The requested access is the union of all elements of the array,
including both objects and reference strings. including both objects and reference strings.
In order to facilitate the use of both object and reference strings In order to facilitate the use of both object and reference strings
to access the same kind of APIs, the API designer can define a clear to access the same kind of APIs, the API designer can define a clear
mapping between these forms. One possible approach for choosing mapping between these forms. One possible approach for choosing
reference string values is to use the same value as the type reference string values is to use the same value as the type
parameter from the fully-specified object, with the API defining a parameter from the fully specified object, with the API defining a
set of default behaviors in this case. For example, an API set of default behaviors in this case. For example, an API
definition could declare the following string: definition could declare the following string:
"access": [ "access": [
"photo-api" "photo-api"
] ]
As being equivalent to the following fully-defined object: As being equivalent to the following fully defined object:
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "read", "write", "delete" ], "actions": [ "read", "write", "delete" ],
"datatypes": [ "metadata", "image" ] "datatypes": [ "metadata", "image" ]
} }
] ]
The exact mechanisms for relating reference strings is up to the API The exact mechanisms for relating reference strings is up to the API
skipping to change at page 140, line 35 skipping to change at line 6172
However, the AS can have limits on its allowed functionality. If the However, the AS can have limits on its allowed functionality. If the
client instance wants to optimize its calls to the AS before making a client instance wants to optimize its calls to the AS before making a
request, it MAY send an HTTP OPTIONS request to the grant request request, it MAY send an HTTP OPTIONS request to the grant request
endpoint to retrieve the server's discovery information. The AS MUST endpoint to retrieve the server's discovery information. The AS MUST
respond with a JSON document with Content-Type application/json respond with a JSON document with Content-Type application/json
containing a single object with the following fields: containing a single object with the following fields:
grant_request_endpoint (string): The location of the AS's grant grant_request_endpoint (string): The location of the AS's grant
request endpoint. The location MUST be an absolute URL [RFC3986] request endpoint. The location MUST be an absolute URL [RFC3986]
with a scheme component (which MUST be "https"), a host component, with a scheme component (which MUST be "https"), a host component,
and optionally, port, path and query components and no fragment and optionally port, path, and query components and no fragment
components. This URL MUST match the URL the client instance used components. This URL MUST match the URL the client instance used
to make the discovery request. REQUIRED. to make the discovery request. REQUIRED.
interaction_start_modes_supported (array of strings): A list of the interaction_start_modes_supported (array of strings): A list of the
AS's interaction start methods. The values of this list AS's interaction start methods. The values of this list
correspond to the possible values for the interaction start correspond to the possible values for the interaction start field
section (Section 2.5.1) of the request and MUST be values from the of the request (Section 2.5.1) and MUST be values from the "GNAP
GNAP Interaction Start Modes Registry (Section 11.9). OPTIONAL. Interaction Start Modes" registry (Section 10.9). OPTIONAL.
interaction_finish_methods_supported (array of strings): A list of interaction_finish_methods_supported (array of strings): A list of
the AS's interaction finish methods. The values of this list the AS's interaction finish methods. The values of this list
correspond to the possible values for the method element of the correspond to the possible values for the method element of the
interaction finish section (Section 2.5.2) of the request and MUST interaction finish field of the request (Section 2.5.2) and MUST
be values from the GNAP Interaction Finish Methods Registry be values from the "GNAP Interaction Finish Methods" registry
(Section 11.10). OPTIONAL. (Section 10.10). OPTIONAL.
key_proofs_supported (array of strings): A list of the AS's key_proofs_supported (array of strings): A list of the AS's
supported key proofing mechanisms. The values of this list supported key proofing mechanisms. The values of this list
correspond to possible values of the proof field of the key correspond to possible values of the proof field of the key
section (Section 7.1) of the request and MUST be values from the section of the request (Section 7.1) and MUST be values from the
GNAP Key Proofing Methods Registry (Section 11.16). OPTIONAL. "GNAP Key Proofing Methods" registry (Section 10.16). OPTIONAL.
sub_id_formats_supported (array of strings): A list of the AS's sub_id_formats_supported (array of strings): A list of the AS's
supported subject identifier formats. The values of this list supported Subject Identifier formats. The values of this list
correspond to possible values of the subject identifier section correspond to possible values of the Subject Identifier field of
(Section 2.2) of the request and MUST be values from the Subject the request (Section 2.2) and MUST be values from the "Subject
Identifier Formats Registry established by [RFC9493]. OPTIONAL. Identifier Formats" registry [Subj-ID-Formats]. OPTIONAL.
assertion_formats_supported (array of strings): A list of the AS's assertion_formats_supported (array of strings): A list of the AS's
supported assertion formats. The values of this list correspond supported assertion formats. The values of this list correspond
to possible values of the subject assertion section (Section 2.2) to possible values of the subject assertion field of the request
of the request and MUST be values from the GNAP Assertion Formats (Section 2.2) and MUST be values from the "GNAP Assertion Formats"
Registry (Section 11.6). OPTIONAL. registry (Section 10.6). OPTIONAL.
key_rotation_supported (boolean): The boolean "true" indicates that key_rotation_supported (boolean): The boolean "true" indicates that
rotation of access token bound keys by the client (Section 6.1.1) rotation of access token bound keys by the client (Section 6.1.1)
is supported by the AS. The absence of this field or a boolean is supported by the AS. The absence of this field or a boolean
"false" value indicates that this feature is not supported. "false" value indicates that this feature is not supported.
The information returned from this method is for optimization The information returned from this method is for optimization
purposes only. The AS MAY deny any request, or any portion of a purposes only. The AS MAY deny any request, or any portion of a
request, even if it lists a capability as supported. For example, a request, even if it lists a capability as supported. For example, if
given client instance can be registered with the mtls key proofing a given client instance can be registered with the mtls key proofing
mechanism, but the AS also returns other proofing methods from the mechanism but the AS also returns other proofing methods from the
discovery document, then the AS will still deny a request from that discovery document, then the AS will still deny a request from that
client instance using a different proofing mechanism. Similarly, an client instance using a different proofing mechanism. Similarly, an
AS with key_rotation_supported set to "true" can still deny any AS with key_rotation_supported set to "true" can still deny any
request for rotating any access token's key for a variety of reasons. request for rotating any access token's key for a variety of reasons.
Additional fields can be defined the GNAP Authorization Server Additional fields can be defined in the "GNAP Authorization Server
Discovery Fields Registry (Section 11.18). Discovery Fields" registry (Section 10.18).
9.1. RS-first Method of AS Discovery 9.1. RS-First Method of AS Discovery
If the client instance calls an RS without an access token, or with If the client instance calls an RS without an access token or with an
an invalid access token, the RS SHOULD be explicit about the fact invalid access token, the RS SHOULD be explicit about the fact that
that GNAP needs to be used to access the resource by responding with GNAP needs to be used to access the resource by responding with the
the WWW-Authenticate header field and a GNAP challenge. WWW-Authenticate header field and a GNAP challenge.
In some situations, the client instance might want to know with which In some situations, the client instance might want to know with which
specific AS it needs to negotiate for access to that RS. The RS MAY specific AS it needs to negotiate for access to that RS. The RS MAY
additionally return the following OPTIONAL parameters: additionally return the following OPTIONAL parameters:
as_uri: The URI of the grant endpoint of the GNAP AS. Used by the as_uri: The URI of the grant endpoint of the GNAP AS. Used by the
client instance to call the AS to request an access token. client instance to call the AS to request an access token.
referrer: The URI of the GNAP RS. Sent by the client instance in referrer: The URI of the GNAP RS. Sent by the client instance in
the Referer header as part of the grant request. the Referer header as part of the grant request.
skipping to change at page 142, line 21 skipping to change at line 6255
rights as well. Sent by the client as an access right in the rights as well. Sent by the client as an access right in the
grant request. grant request.
The client instance SHOULD then use both the referrer and access The client instance SHOULD then use both the referrer and access
parameters in its access token request. The client instance MUST parameters in its access token request. The client instance MUST
check that the referrer parameter is equal to the URI of the RS using check that the referrer parameter is equal to the URI of the RS using
the simple string comparison method in Section 6.2.1 of [RFC3986]. the simple string comparison method in Section 6.2.1 of [RFC3986].
The means for the RS to determine the value for the access reference The means for the RS to determine the value for the access reference
are out of scope of this specification, but some dynamic methods are are out of scope of this specification, but some dynamic methods are
discussed in [I-D.ietf-gnap-resource-servers]. discussed in [GNAP-RS].
When receiving the following response from the RS: When receiving the following response from the RS:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
WWW-Authenticate: \ WWW-Authenticate: \
GNAP as_uri=https://as.example/tx\ GNAP as_uri=https://as.example/tx\
;access=FWWIKYBQ6U56NL1\ ;access=FWWIKYBQ6U56NL1\
;referrer=https://rs.example ;referrer=https://rs.example
skipping to change at page 143, line 31 skipping to change at line 6304
} }
The client instance includes the Referer header field as a way for The client instance includes the Referer header field as a way for
the AS to know that the process is initiated through a discovery the AS to know that the process is initiated through a discovery
process at the RS. process at the RS.
If issued, the resulting access token would contain sufficient access If issued, the resulting access token would contain sufficient access
to be used at both referenced resources. to be used at both referenced resources.
Security considerations, especially related to the potential of a Security considerations, especially related to the potential of a
compromised RS (Section 13.37) redirecting the requests of an compromised RS (Section 11.37) redirecting the requests of an
otherwise properly authenticated client, need to be carefully otherwise properly authenticated client, need to be carefully
considered when allowing such a discovery process. This risk can be considered when allowing such a discovery process. This risk can be
mitigated by an alternative pre-registration process so that the mitigated by an alternative pre-registration process so that the
client knows which AS protects which RS. There are also privacy client knows which AS protects which RS. There are also privacy
considerations related to revealing which AS is protecting a given considerations related to revealing which AS is protecting a given
resource, discussed in Section 14.4.1. resource; these are discussed in Section 12.4.1.
9.2. Dynamic grant endpoint discovery 9.2. Dynamic Grant Endpoint Discovery
Additional methods of discovering the appropriate grant endpoint for Additional methods of discovering the appropriate grant endpoint for
a given application are outside the scope of this specification. a given application are outside the scope of this specification.
This limitation is intentional, as many applications rely on static This limitation is intentional, as many applications rely on static
configuration between the client instance and AS, as is common in configuration between the client instance and AS, as is common in
OAuth 2.0. However, the dynamic nature of GNAP makes it a prime OAuth 2.0. However, the dynamic nature of GNAP makes it a prime
candidate for other extensions defining methods for discovery of the candidate for other extensions defining methods for discovery of the
appropriate AS grant endpoint at runtime. Advanced use cases could appropriate AS grant endpoint at runtime. Advanced use cases could
define contextual methods for contextually providing this endpoint to define contextual methods for securely providing this endpoint to the
the client instance securely. Furthermore, GNAP's design client instance. Furthermore, GNAP's design intentionally requires
intentionally requires the client instance to only know the grant the client instance to only know the grant endpoint and not
endpoint and not additional parameters, since other functions and additional parameters, since other functions and values can be
values can be disclosed and negotiated during the grant process. disclosed and negotiated during the grant process.
10. Acknowledgements
The editors would like to thank the feedback of the following
individuals for their reviews, implementations, and contributions:
Åke Axeland, Aaron Parecki, Adam Omar Oueidat, Andrii Deinega,
Annabelle Backman, Dick Hardt, Dmitri Zagidulin, Dmitry Barinov,
Fabien Imbault, Florian Helmschmidt, Francis Pouatcha, George
Fletcher, Haardik Haardik, Hamid Massaoud, Jacky Yuan, Joseph Heenan,
Justin Richer, Kathleen Moriarty, Leif Johansson, Mike Jones, Mike
Varley, Nat Sakimura, Takahiko Kawasaki, Takahiro Tsuchiya, Yaron
Sheffer.
The editors would also like to thank the GNAP working group design
team of Kathleen Moriarty, Fabien Imbault, Dick Hardt, Mike Jones,
and Justin Richer, who incorporated elements from the XAuth and XYZ
proposals to create the first version of this document.
In addition, the editors would like to thank Aaron Parecki and Mike
Jones for insights into how to integrate identity and authentication
systems into the core protocol, and Justin Richer and Dick Hardt for
the use cases, diagrams, and insights provided in the XYZ and XAuth
proposals that have been incorporated here. The editors would like
to especially thank Mike Varley and the team at SecureKey for
feedback and development of early versions of the XYZ protocol that
fed into this standards work.
Finally, the editors want to acknowledge the immense contributions of
Aaron Parecki to the content of this document. We thank him for his
insight, input, and hard work, without which GNAP would not have
grown to what it is.
11. IANA Considerations 10. IANA Considerations
IANA is requested to add values to existing registries and to create IANA has added values to existing registries as well as created 16
16 registries for the Grant Negotiation and Authorization Protocol registries for GNAP [GNAP-REG] and populated those registries with
and to populate those registries with initial values as described in initial values as described in this section.
this section.
All use of value typing is based on [RFC8259] data types and MUST be All use of value typing is based on data types in [RFC8259] and MUST
one of the following: number, object, string, boolean, or array. be one of the following: number, object, string, boolean, or array.
When the type is array, the contents of the array MUST be specified, When the type is array, the contents of the array MUST be specified,
as in "array of objects" when one subtype is allowed or "array of as in "array of objects" when one subtype is allowed or "array of
strings/objects" when multiple simultaneous subtypes are allowed. strings/objects" when multiple simultaneous subtypes are allowed.
When the type is object, the structure of the object MUST be When the type is object, the structure of the object MUST be
specified in the definition. If a parameter is available in specified in the definition. If a parameter is available in
different types, each type SHOULD be registered separately. different types, each type SHOULD be registered separately.
General guidance for extension parameters is found in Appendix E. General guidance for extension parameters is found in Appendix D.
11.1. HTTP Authentication Scheme Registration
This specification requests registration of the following scheme in
the "Hypertext Transfer Protocol (HTTP) Authentication Scheme
Registry" defined be Section 18.5 of [HTTP]:
* Authentication Scheme Name: GNAP 10.1. HTTP Authentication Scheme Registration
* Reference: Section 7.2 of RFC nnnn IANA has registered of the following scheme in the "HTTP
Authentication Schemes" registry [Auth-Schemes] defined in
Section 18.5 of [HTTP]:
11.2. Media Type Registration Authentication Scheme Name: GNAP
This section requests registration of the following media types Reference: Section 7.2 of RFC 9635
[RFC2046] in the "Media Types" registry [IANA.MediaTypes] in the
manner described in [RFC6838].
To indicate that the content is a GNAP message to be bound with a 10.2. Media Type Registration
detached JWS mechanism:
* Type name: application Per this section, IANA has registered the following media types
[RFC2046] in the "Media Types" registry [MediaTypes] as described in
[RFC6838].
* Subtype name: gnap-binding-jwsd 10.2.1. application/gnap-binding-jwsd
* Required parameters: n/a This media type indicates that the content is a GNAP message to be
bound with a detached JWS mechanism.
* Optional parameters: n/a Type name: application
* Encoding considerations: binary Subtype name: gnap-binding-jwsd
* Security considerations: See Section 13 of RFC nnnn Required parameters: N/A
* Interoperability considerations: n/a Optional parameters: N/A
* Published specification: RFC nnnn Encoding considerations: binary
* Applications that use this media type: GNAP Security considerations: See Section 11 of RFC 9635.
* Fragment identifier considerations: n/a Interoperability considerations: N/A
* Additional information: Published specification: RFC 9635
- Magic number(s): n/a Applications that use this media type: GNAP
- File extension(s): n/a Fragment identifier considerations: N/A
- Macintosh file type code(s): n/a Additional information:
* Person & email address to contact for further information: IETF Deprecated alias names for this type: N/A
GNAP Working Group, txauth@ietf.org Magic number(s): N/A
File extension(s): N/A
Macintosh file type code(s): N/A
* Intended usage: COMMON Person & email address to contact for further information: IETF GNAP
Working Group (txauth@ietf.org)
* Restrictions on usage: none Intended usage: COMMON
* Author: IETF GNAP Working Group, txauth@ietf.org Restrictions on usage: none
* Change Controller: IETF Author: IETF GNAP Working Group (txauth@ietf.org)
* Provisional registration? No Change Controller: IETF
To indicate that the content is a GNAP message to be bound with an 10.2.2. application/gnap-binding-jws
attached JWS mechanism:
* Type name: application This media type indicates that the content is a GNAP message to be
bound with an attached JWS mechanism.
* Subtype name: gnap-binding-jws Type name: application
* Required parameters: n/a Subtype name: gnap-binding-jws
* Optional parameters: n/a Required parameters: N/A
* Encoding considerations: binary Optional parameters: N/A
* Security considerations: See Section 13 of RFC nnnn Encoding considerations: binary
* Interoperability considerations: n/a Security considerations: See Section 11 of RFC 9635.
* Published specification: RFC nnnn Interoperability considerations: N/A
* Applications that use this media type: GNAP Published specification: RFC 9635
* Fragment identifier considerations: n/a Applications that use this media type: GNAP
* Additional information: Fragment identifier considerations: N/A
- Magic number(s): n/a Additional information:
- File extension(s): n/a Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): N/A
Macintosh file type code(s): N/A
- Macintosh file type code(s): n/a Person & email address to contact for further information: IETF GNAP
Working Group (txauth@ietf.org)
* Person & email address to contact for further information: IETF Intended usage: COMMON
GNAP Working Group, txauth@ietf.org
* Intended usage: COMMON Restrictions on usage: none
* Restrictions on usage: none
* Author: IETF GNAP Working Group, txauth@ietf.org Author: IETF GNAP Working Group (txauth@ietf.org)
* Change Controller: IETF Change Controller: IETF
* Provisional registration? No 10.2.3. application/gnap-binding-rotation-jwsd
To indicate that the content is a GNAP token rotation message to be This media type indicates that the content is a GNAP token rotation
bound with a detached JWS mechanism: message to be bound with a detached JWS mechanism.
* Type name: application Type name: application
* Subtype name: gnap-binding-rotation-jwsd Subtype name: gnap-binding-rotation-jwsd
* Required parameters: n/a Required parameters: N/A
* Optional parameters: n/a Optional parameters: N/A
* Encoding considerations: binary Encoding considerations: binary
* Security considerations: See Section 13 of RFC nnnn Security considerations: See Section 11 of RFC 9635.
* Interoperability considerations: n/a Interoperability considerations: N/A
* Published specification: RFC nnnn Published specification: RFC 9635
* Applications that use this media type: GNAP Applications that use this media type: GNAP
* Fragment identifier considerations: n/a Fragment identifier considerations: N/A
* Additional information: Additional information:
- Magic number(s): n/a Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): N/A
Macintosh file type code(s): N/A
- File extension(s): n/a Person & email address to contact for further information: IETF GNAP
Working Group (txauth@ietf.org)
- Macintosh file type code(s): n/a Intended usage: COMMON
* Person & email address to contact for further information: IETF Restrictions on usage: none
GNAP Working Group, txauth@ietf.org
* Intended usage: COMMON Author: IETF GNAP Working Group (txauth@ietf.org)
* Restrictions on usage: none Change Controller: IETF
* Author: IETF GNAP Working Group, txauth@ietf.org 10.2.4. application/gnap-binding-rotation-jws
* Change Controller: IETF
* Provisional registration? No This media type indicates that the content is a GNAP token rotation
message to be bound with an attached JWS mechanism.
To indicate that the content is a GNAP token rotation message to be Type name: application
bound with an attached JWS mechanism:
* Type name: application Subtype name: gnap-binding-rotation-jws
* Subtype name: gnap-binding-rotation-jws Required parameters: N/A
* Required parameters: n/a Optional parameters: N/A
* Optional parameters: n/a Encoding considerations: binary
* Encoding considerations: binary Security considerations: See Section 11 of RFC 9635.
* Security considerations: See Section 13 of RFC nnnn Interoperability considerations: N/A
* Interoperability considerations: n/a Published specification: RFC 9635
* Published specification: RFC nnnn Applications that use this media type: GNAP
* Applications that use this media type: GNAP Fragment identifier considerations: N/A
* Fragment identifier considerations: n/a Additional information:
* Additional information: Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): N/A
Macintosh file type code(s): N/A
- Magic number(s): n/a Person & email address to contact for further information: IETF GNAP
Working Group (txauth@ietf.org)
- File extension(s): n/a Intended usage: COMMON
- Macintosh file type code(s): n/a Restrictions on usage: none
* Person & email address to contact for further information: IETF Author: IETF GNAP Working Group (txauth@ietf.org)
GNAP Working Group, txauth@ietf.org
* Intended usage: COMMON Change Controller: IETF
* Restrictions on usage: none 10.3. GNAP Grant Request Parameters
* Author: IETF GNAP Working Group, txauth@ietf.org This document defines a GNAP grant request, for which IANA has
created and maintains a new registry titled "GNAP Grant Request
Parameters". Initial values for this registry are given in
Section 10.3.2. Future assignments and modifications to existing
assignments are to be made through the Specification Required
registration policy [RFC8126].
* Change Controller: IETF The designated expert (DE) is expected to ensure the following:
* Provisional registration? No * All registrations follow the template presented in Section 10.3.1.
11.3. GNAP Grant Request Parameters * The request parameter's definition is sufficiently orthogonal to
existing functionality provided by existing parameters.
This document defines a GNAP grant request, for which IANA is asked * Registrations for the same name with different types are
to create and maintain a new registry titled "GNAP Grant Request sufficiently close in functionality so as not to cause confusion
Parameters". Initial values for this registry are given in for developers.
Section 11.3.2. Future assignments and modifications to existing
assignment are to be made through the Specification Required
registration policy [RFC8126].
The Designated Expert (DE) is expected to ensure that all * The request parameter's definition specifies the expected behavior
registrations follow the template presented in Section 11.3.1. The of the AS in response to the request parameter for each potential
DE is expected to ensure that the request parameter's definition is state of the grant request.
sufficiently orthogonal to existing functionality provided by
existing parameters. The DE is expected to ensure that registrations
for the same name with different types are sufficiently close in
functionality so as not to cause confusion for developers. The DE is
expected to ensure that the request parameter's definition specifies
the expected behavior of the AS in response to the request parameter
for each potential state of the grant request.
11.3.1. Registration Template 10.3.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Type: Type:
The JSON type allowed for the value. The JSON type allowed for the value.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.3.2. Initial Contents 10.3.2. Initial Contents
+==============+==================+===========================+ +==============+==================+===========================+
| Name | Type | Specification document(s) | | Name | Type | Reference |
+==============+==================+===========================+ +==============+==================+===========================+
| access_token | object | Section 2.1.1 of RFC nnnn | | access_token | object | Section 2.1.1 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
| access_token | array of objects | Section 2.1.2 of RFC nnnn | | access_token | array of objects | Section 2.1.2 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
| subject | object | Section 2.2 of RFC nnnn | | subject | object | Section 2.2 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
| client | object | Section 2.3 of RFC nnnn | | client | object | Section 2.3 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
| client | string | Section 2.3.1 of RFC nnnn | | client | string | Section 2.3.1 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
| user | object | Section 2.4 of RFC nnnn | | user | object | Section 2.4 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
| user | string | Section 2.4.1 of RFC nnnn | | user | string | Section 2.4.1 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
| interact | object | Section 2.5 of RFC nnnn | | interact | object | Section 2.5 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
| interact_ref | string | Section 5.1 of RFC nnnn | | interact_ref | string | Section 5.1 of RFC 9635 |
+--------------+------------------+---------------------------+ +--------------+------------------+---------------------------+
Table 1 Table 1
11.4. GNAP Access Token Flags 10.4. GNAP Access Token Flags
This document defines a GNAP access token flags, for which IANA is This document defines GNAP access token flags, for which IANA has
asked to create and maintain a new registry titled "GNAP Access Token created and maintains a new registry titled "GNAP Access Token
Flags". Initial values for this registry are given in Flags". Initial values for this registry are given in
Section 11.4.2. Future assignments and modifications to existing Section 10.4.2. Future assignments and modifications to existing
assignment are to be made through the Specification Required assignments are to be made through the Specification Required
registration policy [RFC8126]. registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.4.1. The DE is expected to ensure
that the flag specifies whether it applies to requests for tokens to
the AS, responses with tokens from the AS, or both.
11.4.1. Registration Template * All registrations follow the template presented in Section 10.4.1.
* The flag specifies whether it applies to requests for tokens to
the AS, responses with tokens from the AS, or both.
10.4.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Allowed Use: Allowed Use:
Where the flag is allowed to occur. Possible values are Where the flag is allowed to occur. Possible values are
"Request", "Response", and "Request, Response". "Request", "Response", and "Request, Response".
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.4.2. Initial Contents 10.4.2. Initial Contents
+=========+===================+===========================+ +=========+===================+====================+
| Name | Allowed Use | Specification document(s) | | Name | Allowed Use | Reference |
+=========+===================+===========================+ +=========+===================+====================+
| bearer | Request, Response | Section 2.1.1 and | | bearer | Request, Response | Sections 2.1.1 and |
| | | Section 3.2.1 of RFC nnnn | | | | 3.2.1 of RFC 9635 |
+---------+-------------------+---------------------------+ +---------+-------------------+--------------------+
| durable | Response | Section 3.2.1 of RFC nnnn | | durable | Response | Section 3.2.1 of |
+---------+-------------------+---------------------------+ | | | RFC 9635 |
+---------+-------------------+--------------------+
Table 2 Table 2
11.5. GNAP Subject Information Request Fields 10.5. GNAP Subject Information Request Fields
This document defines a means to request subject information from the This document defines a means to request subject information from the
AS to the client instance, for which IANA is asked to create and AS to the client instance, for which IANA has created and maintains a
maintain a new registry titled "GNAP Subject Information Request new registry titled "GNAP Subject Information Request Fields".
Fields". Initial values for this registry are given in Initial values for this registry are given in Section 10.5.2. Future
Section 11.5.2. Future assignments and modifications to existing assignments and modifications to existing assignments are to be made
assignment are to be made through the Specification Required through the Specification Required registration policy [RFC8126].
registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.5.1. The DE is expected to ensure
that registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion for
developers.
11.5.1. Registration Template * All registrations follow the template presented in Section 10.5.1.
* Registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion
for developers.
10.5.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Type: Type:
The JSON type allowed for the value. The JSON type allowed for the value.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.5.2. Initial Contents 10.5.2. Initial Contents
+===================+==================+===========================+ +===================+==================+=========================+
| Name | Type | Specification document(s) | | Name | Type | Reference |
+===================+==================+===========================+ +===================+==================+=========================+
| sub_id_formats | array of strings | Section 2.2 of RFC nnnn | | sub_id_formats | array of strings | Section 2.2 of RFC 9635 |
+-------------------+------------------+---------------------------+ +-------------------+------------------+-------------------------+
| assertion_formats | array of strings | Section 2.2 of RFC nnnn | | assertion_formats | array of strings | Section 2.2 of RFC 9635 |
+-------------------+------------------+---------------------------+ +-------------------+------------------+-------------------------+
| sub_ids | array of objects | Section 2.2 of RFC nnnn | | sub_ids | array of objects | Section 2.2 of RFC 9635 |
+-------------------+------------------+---------------------------+ +-------------------+------------------+-------------------------+
Table 3 Table 3
11.6. GNAP Assertion Formats 10.6. GNAP Assertion Formats
This document defines a means to pass identity assertions between the This document defines a means to pass identity assertions between the
AS and client instance, for which IANA is asked to create and AS and client instance, for which IANA has created and maintains a
maintain a new registry titled "GNAP Assertion Formats". Initial new registry titled "GNAP Assertion Formats". Initial values for
values for this registry are given in Section 11.6.2. Future this registry are given in Section 10.6.2. Future assignments and
assignments and modifications to existing assignment are to be made modifications to existing assignments are to be made through the
through the Specification Required registration policy [RFC8126]. Specification Required registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.6.1. The DE is expected to ensure
that the definition specifies the serialization format of the
assertion value as used within GNAP.
11.6.1. Registration Template * All registrations follow the template presented in Section 10.6.1.
* The definition specifies the serialization format of the assertion
value as used within GNAP.
10.6.1. Registration Template
Name: Name:
An identifier for the assertion format. An identifier for the assertion format.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.6.2. Initial Contents 10.6.2. Initial Contents
+==========+===========================+ +==========+===========================+
| Name | Specification document(s) | | Name | Reference |
+==========+===========================+ +==========+===========================+
| id_token | Section 3.4.1 of RFC nnnn | | id_token | Section 3.4.1 of RFC 9635 |
+----------+---------------------------+ +----------+---------------------------+
| saml2 | Section 3.4.1 of RFC nnnn | | saml2 | Section 3.4.1 of RFC 9635 |
+----------+---------------------------+ +----------+---------------------------+
Table 4 Table 4
11.7. GNAP Client Instance Fields 10.7. GNAP Client Instance Fields
This document defines a means to send information about the client This document defines a means to send information about the client
instance, for which IANA is asked to create and maintain a new instance, for which IANA has created and maintains a new registry
registry titled "GNAP Client Instance Fields". Initial values for titled "GNAP Client Instance Fields". Initial values for this
this registry are given in Section 11.7.2. Future assignments and registry are given in Section 10.7.2. Future assignments and
modifications to existing assignment are to be made through the modifications to existing assignments are to be made through the
Specification Required registration policy [RFC8126]. Specification Required registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.7.1. The DE is expected to ensure
that registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion for
developers.
11.7.1. Registration Template * All registrations follow the template presented in Section 10.7.1.
* Registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion
for developers.
10.7.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Type: Type:
The JSON type allowed for the value. The JSON type allowed for the value.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.7.2. Initial Contents 10.7.2. Initial Contents
+==========+========+===========================+ +==========+========+===========================+
| Name | Type | Specification document(s) | | Name | Type | Reference |
+==========+========+===========================+ +==========+========+===========================+
| key | object | Section 7.1 of RFC nnnn | | key | object | Section 7.1 of RFC 9635 |
+----------+--------+---------------------------+ +----------+--------+---------------------------+
| key | string | Section 7.1.1 of RFC nnnn | | key | string | Section 7.1.1 of RFC 9635 |
+----------+--------+---------------------------+ +----------+--------+---------------------------+
| class_id | string | Section 2.3 of RFC nnnn | | class_id | string | Section 2.3 of RFC 9635 |
+----------+--------+---------------------------+ +----------+--------+---------------------------+
| display | object | Section 2.3.2 of RFC nnnn | | display | object | Section 2.3.2 of RFC 9635 |
+----------+--------+---------------------------+ +----------+--------+---------------------------+
Table 5 Table 5
11.8. GNAP Client Instance Display Fields 10.8. GNAP Client Instance Display Fields
This document defines a means to send end-user facing displayable This document defines a means to send end-user-facing displayable
information about the client instance, for which IANA is asked to information about the client instance, for which IANA has created and
create and maintain a new registry titled "GNAP Client Instance maintains a new registry titled "GNAP Client Instance Display
Display Fields". Initial values for this registry are given in Fields". Initial values for this registry are given in
Section 11.8.2. Future assignments and modifications to existing Section 10.8.2. Future assignments and modifications to existing
assignment are to be made through the Specification Required assignments are to be made through the Specification Required
registration policy [RFC8126]. registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.8.1. The DE is expected to ensure
that registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion for
developers.
11.8.1. Registration Template * All registrations follow the template presented in Section 10.8.1.
* Registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion
for developers.
10.8.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Type: Type:
The JSON type allowed for the value. The JSON type allowed for the value.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.8.2. Initial Contents 10.8.2. Initial Contents
+==========+========+===========================+ +==========+========+===========================+
| Name | Type | Specification document(s) | | Name | Type | Reference |
+==========+========+===========================+ +==========+========+===========================+
| name | string | Section 2.3.2 of RFC nnnn | | name | string | Section 2.3.2 of RFC 9635 |
+----------+--------+---------------------------+ +----------+--------+---------------------------+
| uri | string | Section 2.3.2 of RFC nnnn | | uri | string | Section 2.3.2 of RFC 9635 |
+----------+--------+---------------------------+ +----------+--------+---------------------------+
| logo_uri | string | Section 2.3.2 of RFC nnnn | | logo_uri | string | Section 2.3.2 of RFC 9635 |
+----------+--------+---------------------------+ +----------+--------+---------------------------+
Table 6 Table 6
11.9. GNAP Interaction Start Modes 10.9. GNAP Interaction Start Modes
This document defines a means for the client instance to begin This document defines a means for the client instance to begin
interaction between the end-user and the AS, for which IANA is asked interaction between the end user and the AS, for which IANA has
to create and maintain a new registry titled "GNAP Interaction Start created and maintains a new registry titled "GNAP Interaction Start
Modes". Initial values for this registry are given in Modes". Initial values for this registry are given in
Section 11.9.2. Future assignments and modifications to existing Section 10.9.2. Future assignments and modifications to existing
assignment are to be made through the Specification Required assignments are to be made through the Specification Required
registration policy [RFC8126]. registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.9.1. The DE is expected to ensure
that registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion for
developers. The DE is expected to ensure that any registration using
an "object" type declares all additional parameters, their
optionality, and purpose. The DE is expected to ensure that the
start mode clearly defines what actions the client is expected to
take to begin interaction, what the expected user experience is, and
any security considerations for this communication from either party.
The DE is expected to ensure that the start mode documents
incompatibilities with other start modes or finish methods, if
applicable. The DE is expected to ensure that the start mode
provides enough information to uniquely identify the grant request
during the interaction. For example, tn the redirect and app modes,
this is done using a unique URI (including its parameters). In the
user_code and user_code_uri mode, this is done using the value of the
user code.
11.9.1. Registration Template * All registrations follow the template presented in Section 10.9.1.
* Registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion
for developers.
* Any registration using an "object" type declares all additional
parameters, their optionality, and their purpose.
* The start mode clearly defines what actions the client is expected
to take to begin interaction, what the expected user experience
is, and any security considerations for this communication from
either party.
* The start mode documents incompatibilities with other start modes
or finish methods, if applicable.
* The start mode provides enough information to uniquely identify
the grant request during the interaction. For example, in the
redirect and app modes, this is done using a unique URI (including
its parameters). In the user_code and user_code_uri modes, this
is done using the value of the user code.
10.9.1. Registration Template
Mode: Mode:
An identifier for the interaction start mode. An identifier for the interaction start mode.
Type: Type:
The JSON type for the value, either "string" or "object", as The JSON type for the value, either "string" or "object", as
described in Section 2.5.1. described in Section 2.5.1.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.9.2. Initial Contents 10.9.2. Initial Contents
+===============+========+=============================+ +===============+========+=============================+
| Mode | Type | Specification document(s) | | Mode | Type | Reference |
+===============+========+=============================+ +===============+========+=============================+
| redirect | string | Section 2.5.1.1 of RFC nnnn | | redirect | string | Section 2.5.1.1 of RFC 9635 |
+---------------+--------+-----------------------------+ +---------------+--------+-----------------------------+
| app | string | Section 2.5.1.2 of RFC nnnn | | app | string | Section 2.5.1.2 of RFC 9635 |
+---------------+--------+-----------------------------+ +---------------+--------+-----------------------------+
| user_code | string | Section 2.5.1.3 of RFC nnnn | | user_code | string | Section 2.5.1.3 of RFC 9635 |
+---------------+--------+-----------------------------+ +---------------+--------+-----------------------------+
| user_code_uri | string | Section 2.5.1.4 of RFC nnnn | | user_code_uri | string | Section 2.5.1.4 of RFC 9635 |
+---------------+--------+-----------------------------+ +---------------+--------+-----------------------------+
Table 7 Table 7
11.10. GNAP Interaction Finish Methods 10.10. GNAP Interaction Finish Methods
This document defines a means for the client instance to be notified This document defines a means for the client instance to be notified
of the end of interaction between the end-user and the AS, for which of the end of interaction between the end user and the AS, for which
IANA is asked to create and maintain a new registry titled "GNAP IANA has created and maintains a new registry titled "GNAP
Interaction Finish Methods". Initial values for this registry are Interaction Finish Methods". Initial values for this registry are
given in Section 11.10.2. Future assignments and modifications to given in Section 10.10.2. Future assignments and modifications to
existing assignment are to be made through the Specification Required existing assignments are to be made through the Specification
registration policy [RFC8126]. Required registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.10.1. The DE is expected to ensure
that all finish methods clearly define what actions the AS is
expected to take, what listening methods the client instance needs to
enable, and any security considerations for this communication from
either party. The DE is expected to ensure that all finish methods
document incompatibilities with any start modes, if applicable.
11.10.1. Registration Template * All registrations follow the template presented in
Section 10.10.1.
* All finish methods clearly define what actions the AS is expected
to take, what listening methods the client instance needs to
enable, and any security considerations for this communication
from either party.
* All finish methods document incompatibilities with any start
modes, if applicable.
10.10.1. Registration Template
Method: Method:
An identifier for the interaction finish method. An identifier for the interaction finish method.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.10.2. Initial Contents 10.10.2. Initial Contents
+==========+=============================+ +==========+=============================+
| Mode | Specification document(s) | | Method | Reference |
+==========+=============================+ +==========+=============================+
| redirect | Section 2.5.2.1 of RFC nnnn | | redirect | Section 2.5.2.1 of RFC 9635 |
+----------+-----------------------------+ +----------+-----------------------------+
| push | Section 2.5.2.2 of RFC nnnn | | push | Section 2.5.2.2 of RFC 9635 |
+----------+-----------------------------+ +----------+-----------------------------+
Table 8 Table 8
11.11. GNAP Interaction Hints 10.11. GNAP Interaction Hints
This document defines a set of hints that a client instance can This document defines a set of hints that a client instance can
provide to the AS to facilitate interaction with the end user, for provide to the AS to facilitate interaction with the end user, for
which IANA is asked to create and maintain a new registry titled which IANA has created and maintains a new registry titled "GNAP
"GNAP Interaction Hints". Initial values for this registry are given Interaction Hints". Initial values for this registry are given in
in Section 11.11.2. Future assignments and modifications to existing Section 10.11.2. Future assignments and modifications to existing
assignment are to be made through the Specification Required assignments are to be made through the Specification Required
registration policy [RFC8126]. registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.11.1. The DE is expected to ensure
that all interaction hints clearly document the expected behaviors of
the AS in response to the hint, and that an AS not processing the
hint does not impede the operation of the AS or client instance.
11.11.1. Registration Template * All registrations follow the template presented in
Section 10.11.1.
* All interaction hints clearly document the expected behaviors of
the AS in response to the hint, and an AS not processing the hint
does not impede the operation of the AS or client instance.
10.11.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.11.2. Initial Contents 10.11.2. Initial Contents
+============+===========================+ +============+===========================+
| Mode | Specification document(s) | | Name | Reference |
+============+===========================+ +============+===========================+
| ui_locales | Section 2.5.3 of RFC nnnn | | ui_locales | Section 2.5.3 of RFC 9635 |
+------------+---------------------------+ +------------+---------------------------+
Table 9 Table 9
11.12. GNAP Grant Response Parameters 10.12. GNAP Grant Response Parameters
This document defines a GNAP grant response, for which IANA is asked This document defines a GNAP grant response, for which IANA has
to create and maintain a new registry titled "GNAP Grant Response created and maintains a new registry titled "GNAP Grant Response
Parameters". Initial values for this registry are given in Parameters". Initial values for this registry are given in
Section 11.12.2. Future assignments and modifications to existing Section 10.12.2. Future assignments and modifications to existing
assignment are to be made through the Specification Required assignments are to be made through the Specification Required
registration policy [RFC8126]. registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.12.1. The DE is expected to ensure
that the response parameter's definition is sufficiently orthogonal
to existing functionality provided by existing parameters. The DE is
expected to ensure that registrations for the same name with
different types are sufficiently close in functionality so as not to
cause confusion for developers. The DE is expected to ensure that
the response parameter's definition specifies grant states for which
the client instance can expect this parameter to appear in a response
message.
11.12.1. Registration Template * All registrations follow the template presented in
Section 10.12.1.
* The response parameter's definition is sufficiently orthogonal to
existing functionality provided by existing parameters.
* Registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion
for developers.
* The response parameter's definition specifies grant states for
which the client instance can expect this parameter to appear in a
response message.
10.12.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Type: Type:
The JSON type allowed for the value. The JSON type allowed for the value.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.12.2. Initial Contents 10.12.2. Initial Contents
+=============+==================+===========================+ +=============+==================+===========================+
| Name | Type | Specification document(s) | | Name | Type | Reference |
+=============+==================+===========================+ +=============+==================+===========================+
| continue | object | Section 3.1 of RFC nnnn | | continue | object | Section 3.1 of RFC 9635 |
+-------------+------------------+---------------------------+ +-------------+------------------+---------------------------+
| acces_token | object | Section 3.2.1 of RFC nnnn | | acces_token | object | Section 3.2.1 of RFC 9635 |
+-------------+------------------+---------------------------+ +-------------+------------------+---------------------------+
| acces_token | array of objects | Section 3.2.2 of RFC nnnn | | acces_token | array of objects | Section 3.2.2 of RFC 9635 |
+-------------+------------------+---------------------------+ +-------------+------------------+---------------------------+
| interact | object | Section 3.3 of RFC nnnn | | interact | object | Section 3.3 of RFC 9635 |
+-------------+------------------+---------------------------+ +-------------+------------------+---------------------------+
| subject | object | Section 3.4 of RFC nnnn | | subject | object | Section 3.4 of RFC 9635 |
+-------------+------------------+---------------------------+ +-------------+------------------+---------------------------+
| instance_id | string | Section 3.5 of RFC nnnn | | instance_id | string | Section 3.5 of RFC 9635 |
+-------------+------------------+---------------------------+ +-------------+------------------+---------------------------+
| error | object | Section 3.6 of RFC nnnn | | error | object | Section 3.6 of RFC 9635 |
+-------------+------------------+---------------------------+ +-------------+------------------+---------------------------+
Table 10 Table 10
11.13. GNAP Interaction Mode Responses 10.13. GNAP Interaction Mode Responses
This document defines a means for the AS to provide to the client This document defines a means for the AS to provide the client
instance information that is required to complete a particular instance with information that is required to complete a particular
interaction mode, for which IANA is asked to create and maintain a interaction mode, for which IANA has created and maintains a new
new registry titled "GNAP Interaction Mode Responses". Initial registry titled "GNAP Interaction Mode Responses". Initial values
values for this registry are given in Section 11.13.2. Future for this registry are given in Section 10.13.2. Future assignments
assignments and modifications to existing assignment are to be made and modifications to existing assignments are to be made through the
through the Specification Required registration policy [RFC8126]. Specification Required registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.13.1. If the name of the
registration matches the name of an interaction start mode, the DE is
expected to ensure that the response parameter is unambiguously
associated with the interaction start mode of the same name.
11.13.1. Registration Template * All registrations follow the template presented in
Section 10.13.1.
* If the name of the registration matches the name of an interaction
start mode, the response parameter is unambiguously associated
with the interaction start mode of the same name.
10.13.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.13.2. Initial Contents 10.13.2. Initial Contents
+===============+===========================+ +===============+=========================+
| Name | Specification document(s) | | Name | Reference |
+===============+===========================+ +===============+=========================+
| redirect | Section 3.3 of RFC nnnn | | redirect | Section 3.3 of RFC 9635 |
+---------------+---------------------------+ +---------------+-------------------------+
| app | Section 3.3 of RFC nnnn | | app | Section 3.3 of RFC 9635 |
+---------------+---------------------------+ +---------------+-------------------------+
| user_code | Section 3.3 of RFC nnnn | | user_code | Section 3.3 of RFC 9635 |
+---------------+---------------------------+ +---------------+-------------------------+
| user_code_uri | Section 3.3 of RFC nnnn | | user_code_uri | Section 3.3 of RFC 9635 |
+---------------+---------------------------+ +---------------+-------------------------+
| finish | Section 3.3 of RFC nnnn | | finish | Section 3.3 of RFC 9635 |
+---------------+---------------------------+ +---------------+-------------------------+
| expires_in | Section 3.3 of RFC nnnn | | expires_in | Section 3.3 of RFC 9635 |
+---------------+---------------------------+ +---------------+-------------------------+
Table 11 Table 11
11.14. GNAP Subject Information Response Fields 10.14. GNAP Subject Information Response Fields
This document defines a means to return subject information from the This document defines a means to return subject information from the
AS to the client instance, for which IANA is asked to create and AS to the client instance, for which IANA has created and maintains a
maintain a new registry titled "GNAP Subject Information Response new registry titled "GNAP Subject Information Response Fields".
Fields". Initial values for this registry are given in Initial values for this registry are given in Section 10.14.2.
Section 11.14.2. Future assignments and modifications to existing Future assignments and modifications to existing assignments are to
assignment are to be made through the Specification Required be made through the Specification Required registration policy
registration policy [RFC8126]. [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.14.1. The DE is expected to ensure
that registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion for
developers.
11.14.1. Registration Template * All registrations follow the template presented in
Section 10.14.1.
* Registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion
for developers.
10.14.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Type: Type:
The JSON type allowed for the value. The JSON type allowed for the value.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.14.2. Initial Contents 10.14.2. Initial Contents
+============+==================+=========================+
| Name | Type | Reference |
+============+==================+=========================+
| sub_ids | array of objects | Section 3.4 of RFC 9635 |
+------------+------------------+-------------------------+
| assertions | array of objects | Section 3.4 of RFC 9635 |
+------------+------------------+-------------------------+
| updated_at | string | Section 3.4 of RFC 9635 |
+------------+------------------+-------------------------+
+============+==================+===========================+
| Name | Type | Specification document(s) |
+============+==================+===========================+
| sub_ids | array of objects | Section 3.4 of RFC nnnn |
+------------+------------------+---------------------------+
| assertions | array of objects | Section 3.4 of RFC nnnn |
+------------+------------------+---------------------------+
| updated_at | string | Section 3.4 of RFC nnnn |
+------------+------------------+---------------------------+
Table 12 Table 12
11.15. GNAP Error Codes 10.15. GNAP Error Codes
This document defines a set of errors that the AS can return to the This document defines a set of errors that the AS can return to the
client instance, for which IANA is asked to create and maintain a new client instance, for which IANA has created and maintains a new
registry titled "GNAP Error Codes". Initial values for this registry registry titled "GNAP Error Codes". Initial values for this registry
are given in Section 11.15.2. Future assignments and modifications are given in Section 10.15.2. Future assignments and modifications
to existing assignment are to be made through the Specification to existing assignments are to be made through the Specification
Required registration policy [RFC8126]. Required registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.15.1. The DE is expected to ensure
that the error response is sufficiently unique from other errors to
provide actionable information to the client instance. The DE is
expected to ensure that the definition of the error response
specifies all conditions in which the error response is returned, and
what the client instance's expected action is.
11.15.1. Registration Template * All registrations follow the template presented in
Section 10.15.1.
* The error response is sufficiently unique from other errors to
provide actionable information to the client instance.
* The definition of the error response specifies all conditions in
which the error response is returned and the client instance's
expected action.
10.15.1. Registration Template
Error: Error:
A unique string code for the error. A unique string code for the error.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.15.2. Initial Contents 10.15.2. Initial Contents
+============================+===========================+ +============================+=========================+
| Error | Specification document(s) | | Error | Reference |
+============================+===========================+ +============================+=========================+
| invalid_request | Section 3.6 of RFC nnnn | | invalid_request | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| invalid_client | Section 3.6 of RFC nnnn | | invalid_client | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| invalid_interaction | Section 3.6 of RFC nnnn | | invalid_interaction | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| invalid_flag | Section 3.6 of RFC nnnn | | invalid_flag | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| invalid_rotation | Section 3.6 of RFC nnnn | | invalid_rotation | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| key_rotation_not_supported | Section 3.6 of RFC nnnn | | key_rotation_not_supported | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| invalid_continuation | Section 3.6 of RFC nnnn | | invalid_continuation | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| user_denied | Section 3.6 of RFC nnnn | | user_denied | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| request_denied | Section 3.6 of RFC nnnn | | request_denied | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| unknown_interaction | Section 3.6 of RFC nnnn | | unknown_user | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| too_fast | Section 3.6 of RFC nnnn | | unknown_interaction | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| too_many_attempts | Section 3.6 of RFC nnnn | | too_fast | Section 3.6 of RFC 9635 |
+----------------------------+---------------------------+ +----------------------------+-------------------------+
| too_many_attempts | Section 3.6 of RFC 9635 |
+----------------------------+-------------------------+
Table 13 Table 13
11.16. GNAP Key Proofing Methods 10.16. GNAP Key Proofing Methods
This document defines methods that the client instance can use to This document defines methods that the client instance can use to
prove possession of a key, for which IANA is asked to create and prove possession of a key, for which IANA has created and maintains a
maintain a new registry titled "GNAP Key Proofing Methods". Initial new registry titled "GNAP Key Proofing Methods". Initial values for
values for this registry are given in Section 11.16.2. Future this registry are given in Section 10.16.2. Future assignments and
assignments and modifications to existing assignment are to be made modifications to existing assignments are to be made through the
through the Specification Required registration policy [RFC8126]. Specification Required registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.16.1. The DE is expected to ensure
that registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion for
developers. The DE is expected to ensure that the proofing method
provides sufficient coverage of and binding to the protocol messages
to which it is applied. The DE is expected to ensure that the
proofing method definition clearly enumerates how all requirements in
Section 7.3 are fulfilled by the definition.
11.16.1. Registration Template * All registrations follow the template presented in
Section 10.16.1.
* Registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion
for developers.
* The proofing method provides sufficient coverage of and binding to
the protocol messages to which it is applied.
* The proofing method definition clearly enumerates how all
requirements in Section 7.3 are fulfilled by the definition.
10.16.1. Registration Template
Method: Method:
A unique string code for the key proofing method. A unique string code for the key proofing method.
Type: Type:
The JSON type allowed for the value. The JSON type allowed for the value.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.16.2. Initial Contents 10.16.2. Initial Contents
+=========+========+===========================+ +=========+========+===========================+
| Method | Type | Specification document(s) | | Method | Type | Reference |
+=========+========+===========================+ +=========+========+===========================+
| httpsig | string | Section 7.3.1 of RFC nnnn | | httpsig | string | Section 7.3.1 of RFC 9635 |
+---------+--------+---------------------------+ +---------+--------+---------------------------+
| httpsig | object | Section 7.3.1 of RFC nnnn | | httpsig | object | Section 7.3.1 of RFC 9635 |
+---------+--------+---------------------------+ +---------+--------+---------------------------+
| mtls | string | Section 7.3.2 of RFC nnnn | | mtls | string | Section 7.3.2 of RFC 9635 |
+---------+--------+---------------------------+ +---------+--------+---------------------------+
| jwsd | string | Section 7.3.3 of RFC nnnn | | jwsd | string | Section 7.3.3 of RFC 9635 |
+---------+--------+---------------------------+ +---------+--------+---------------------------+
| jws | string | Section 7.3.4 of RFC nnnn | | jws | string | Section 7.3.4 of RFC 9635 |
+---------+--------+---------------------------+ +---------+--------+---------------------------+
Table 14 Table 14
11.17. GNAP Key Formats 10.17. GNAP Key Formats
This document defines formats for a public key value, for which IANA This document defines formats for a public key value, for which IANA
is asked to create and maintain a new registry titled "GNAP Key has created and maintains a new registry titled "GNAP Key Formats".
Formats". Initial values for this registry are given in Initial values for this registry are given in Section 10.17.2.
Section 11.17.2. Future assignments and modifications to existing Future assignments and modifications to existing assignments are to
assignment are to be made through the Specification Required be made through the Specification Required registration policy
registration policy [RFC8126]. [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.17.1. The DE is expected to ensure
the key format specifies the structure and serialization of the key
material.
11.17.1. Registration Template * All registrations follow the template presented in
Section 10.17.1.
* The key format specifies the structure and serialization of the
key material.
10.17.1. Registration Template
Format: Format:
A unique string code for the key format. A unique string code for the key format.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.17.2. Initial Contents 10.17.2. Initial Contents
+===========+===========================+ +===========+=========================+
| Format | Specification document(s) | | Format | Reference |
+===========+===========================+ +===========+=========================+
| jwk | Section 7.1 of RFC nnnn | | jwk | Section 7.1 of RFC 9635 |
+-----------+---------------------------+ +-----------+-------------------------+
| cert | Section 7.1 of RFC nnnn | | cert | Section 7.1 of RFC 9635 |
+-----------+---------------------------+ +-----------+-------------------------+
| cert#S256 | Section 7.1 of RFC nnnn | | cert#S256 | Section 7.1 of RFC 9635 |
+-----------+---------------------------+ +-----------+-------------------------+
Table 15 Table 15
11.18. GNAP Authorization Server Discovery Fields 10.18. GNAP Authorization Server Discovery Fields
This document defines a discovery document for an AS, for which IANA This document defines a discovery document for an AS, for which IANA
is asked to create and maintain a new registry titled "GNAP has created and maintains a new registry titled "GNAP Authorization
Authorization Server Discovery Fields". Initial values for this Server Discovery Fields". Initial values for this registry are given
registry are given in Section 11.18.2. Future assignments and in Section 10.18.2. Future assignments and modifications to existing
modifications to existing assignment are to be made through the assignments are to be made through the Specification Required
Specification Required registration policy [RFC8126]. registration policy [RFC8126].
The DE is expected to ensure that all registrations follow the The DE is expected to ensure the following:
template presented in Section 11.18.1. The DE is expected to ensure
that registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion for
developers. The DE is expected to ensure that the values in the
discovery document are sufficient to provide optimization and hints
to the client instance, but that knowledge of the discovered value is
not required for starting a transaction with the AS.
11.18.1. Registration Template * All registrations follow the template presented in
Section 10.18.1.
* Registrations for the same name with different types are
sufficiently close in functionality so as not to cause confusion
for developers.
* The values in the discovery document are sufficient to provide
optimization and hints to the client instance, but knowledge of
the discovered value is not required for starting a transaction
with the AS.
10.18.1. Registration Template
Name: Name:
An identifier for the parameter. An identifier for the parameter.
Type: Type:
The JSON type allowed for the value. The JSON type allowed for the value.
Specification document(s): Reference:
Reference to the document(s) that specify the value, preferably Reference to one or more documents that specify the value,
including a URI that can be used to retrieve a copy of the preferably including a URI that can be used to retrieve a copy of
document(s). An indication of the relevant sections may also be the document(s). An indication of the relevant sections may also
included but is not required. be included but is not required.
11.18.2. Initial Contents 10.18.2. Initial Contents
+======================================+==========+===============+ +======================================+==========+=============+
| Name | Type | Specification | | Name | Type | Reference |
| | | document(s) | +======================================+==========+=============+
+======================================+==========+===============+ | grant_request_endpoint | string | Section 9 |
| grant_request_endpoint | string | Section 9 of | | | | of RFC 9635 |
| | | RFC nnnn | +--------------------------------------+----------+-------------+
+--------------------------------------+----------+---------------+ | interaction_start_modes_supported | array of | Section 9 |
| interaction_start_modes_supported | array of | Section 9 of | | | strings | of RFC 9635 |
| | strings | RFC nnnn | +--------------------------------------+----------+-------------+
+--------------------------------------+----------+---------------+ | interaction_finish_methods_supported | array of | Section 9 |
| interaction_finish_methods_supported | array of | Section 9 of | | | strings | of RFC 9635 |
| | strings | RFC nnnn | +--------------------------------------+----------+-------------+
+--------------------------------------+----------+---------------+ | key_proofs_supported | array of | Section 9 |
| key_proofs_supported | array of | Section 9 of | | | strings | of RFC 9635 |
| | strings | RFC nnnn | +--------------------------------------+----------+-------------+
+--------------------------------------+----------+---------------+ | sub_id_formats_supported | array of | Section 9 |
| sub_id_formats_supported | array of | Section 9 of | | | strings | of RFC 9635 |
| | strings | RFC nnnn | +--------------------------------------+----------+-------------+
+--------------------------------------+----------+---------------+ | assertion_formats_supported | array of | Section 9 |
| assertion_formats_supported | array of | Section 9 of | | | strings | of RFC 9635 |
| | strings | RFC nnnn | +--------------------------------------+----------+-------------+
+--------------------------------------+----------+---------------+ | key_rotation_supported | boolean | Section 9 |
| key_rotation_supported | boolean | Section 9 of | | | | of RFC 9635 |
| | | RFC nnnn | +--------------------------------------+----------+-------------+
+--------------------------------------+----------+---------------+
Table 16 Table 16
12. Implementation Status 11. Security Considerations
Note: To be removed by RFC editor before publication.
*GNAP Authorization Service in Rust* implementation by David Skyberg.
https://github.com/dskyberg/gnap (https://github.com/dskyberg/gnap)
Prototype implementation of AS and client in Rust. MIT license.
*GNAP JS Client* from Interop Alliance, implementation by Dmitri
Zagidulin. https://github.com/interop-alliance/gnap-client-js
(https://github.com/interop-alliance/gnap-client-js) Prototype
implementation of client in JavaScript. MIT License.
*Rafiki* from Interledger Foundation. https://github.com/interledger/
rafiki (https://github.com/interledger/rafiki) Production
implementation of AS in JavaScript. Apache 2.0 license.
*Sample GNAP Client in PHP* implementation by Aaron Parecki.
https://github.com/aaronpk/gnap-client-php
(https://github.com/aaronpk/gnap-client-php) Prototype implementation
of web application client and CLI client in PHP, with common support
library. CC0 license.
*SUNET Auth Server* from SUNET. https://github.com/SUNET/sunet-auth-
server (https://github.com/SUNET/sunet-auth-server) Production
implementation of AS in Python. BSD license.
*Trustbloc* from Gen Digital.
https://github.com/trustbloc/docs/blob/main/readthedocs/designs/
auth.md
(https://github.com/trustbloc/docs/blob/main/readthedocs/designs/
auth.md) Production implementation of AS and client in Go. Apache
2.0 license.
*Verified.ME* from SecureKey. https://verified.me/
(https://verified.me/) Production implementation of AS, client and
RS. Proprietary license.
*XYZ* from Bespoke Engineering, implementation by Justin Richer.
https://github.com/bspk/oauth.xyz-java (https://github.com/bspk/
oauth.xyz-java) Advanced prototype implementation of AS, client, and
RS in Java, with common support library. Prototype implementation of
SPA client in JavaScript. Apache 2.0 license.
13. Security Considerations
In addition to the normative requirements in this document, In addition to the normative requirements in this document,
implementors are strongly encouraged to consider these additional implementors are strongly encouraged to consider these additional
security considerations in implementations and deployments of GNAP. security considerations in implementations and deployments of GNAP.
13.1. TLS Protection in Transit 11.1. TLS Protection in Transit
All requests in GNAP made over untrusted network connections have to All requests in GNAP made over untrusted network connections have to
be made over TLS as outlined in [BCP195] to protect the contents of be made over TLS as outlined in [BCP195] to protect the contents of
the request and response from manipulation and interception by an the request and response from manipulation and interception by an
attacker. This includes all requests from a client instance to the attacker. This includes all requests from a client instance to the
AS, all requests from the client instance to an RS, and any requests AS, all requests from the client instance to an RS, and any requests
back to a client instance such as the push-based interaction finish back to a client instance such as the push-based interaction finish
method. Additionally, all requests between a browser and other method. Additionally, all requests between a browser and other
components, such as during redirect-based interaction, need to be components, such as during redirect-based interaction, need to be
made over TLS or use equivalent protection such as a network made over TLS or use equivalent protection such as a network
connection local to the browser ("localhost"). connection local to the browser ("localhost").
Even though requests from the client instance to the AS are signed, Even though requests from the client instance to the AS are signed,
the signature method alone does not protect the request from the signature method alone does not protect the request from
interception by an attacker. TLS protects the response as well as interception by an attacker. TLS protects the response as well as
the request, preventing an attacker from intercepting requested the request, preventing an attacker from intercepting requested
information as it is returned. This is particularly important in the information as it is returned. This is particularly important in
core protocol for security artifacts such as nonces and for personal this specification for security artifacts such as nonces and for
information such as subject information. personal information such as subject information.
The use of key-bound access tokens does not negate the requirement The use of key-bound access tokens does not negate the requirement
for protecting calls to the RS with TLS. While the keys and for protecting calls to the RS with TLS. The keys and signatures
signatures associated a bound access token will prevent an attacker associated with a bound access token will prevent an attacker from
from using a stolen token, without TLS an attacker would be able to using a stolen token; however, without TLS, an attacker would be able
watch the data being sent to the RS and returned from the RS during to watch the data being sent to the RS and returned from the RS
legitimate use of the client instance under attack. Additionally, during legitimate use of the client instance under attack.
without TLS an attacker would be able to profile the calls made Additionally, without TLS, an attacker would be able to profile the
between the client instance and RS, possibly gaining information calls made between the client instance and RS, possibly gaining
about the functioning of the API between the client software and RS information about the functioning of the API between the client
software that would be otherwise unknown to the attacker. software and RS software that would otherwise be unknown to the
attacker.
Note that connections from the end user and RO's browser also need to Note that connections from the end user and RO's browser also need to
be be protected with TLS. This applies during initial redirects to be protected with TLS. This applies during initial redirects to an
an AS's components during interaction, during any interaction with AS's components during interaction, during any interaction with the
the resource owner, and during any redirect back to the client RO, and during any redirect back to the client instance. Without TLS
instance. Without TLS protection on these portions of the process, protection on these portions of the process, an attacker could wait
an attacker could wait for a valid request to start and then take for a valid request to start and then take over the RO's interaction
over the resource owner's interaction session. session.
13.2. Signing Requests from the Client Software 11.2. Signing Requests from the Client Software
Even though all requests in GNAP need to be transmitted over TLS or Even though all requests in GNAP need to be transmitted over TLS or
its equivalent, the use of TLS alone is not sufficient to protect all its equivalent, the use of TLS alone is not sufficient to protect all
parts of a multi-party and multi-stage protocol like GNAP, and TLS is parts of a multi-party and multi-stage protocol like GNAP, and TLS is
not targeted at tying multiple requests to each other over time. To not targeted at tying multiple requests to each other over time. To
account for this, GNAP makes use of message-level protection and key account for this, GNAP makes use of message-level protection and key
presentation mechanisms that strongly associate a request with a key presentation mechanisms that strongly associate a request with a key
held by the client instance (see Section 7). held by the client instance (see Section 7).
During the initial request from a client instance to the AS, the During the initial request from a client instance to the AS, the
client instance has to identify and prove possession of a client instance has to identify and prove possession of a
cryptographic key. If the key is known to the AS, such as if it is cryptographic key. If the key is known to the AS, e.g., previously
previously registered or dereferenceable to a trusted source, the AS registered or dereferenceable to a trusted source, the AS can
can associate a set of policies to the client instance identified by associate a set of policies to the client instance identified by the
the key. Without the requirement that the client instance prove that key. Without the requirement that the client instance prove that it
it holds that key, the AS could not trust that the connection came holds that key, the AS could not trust that the connection came from
from any particular client and could not apply any associated any particular client and could not apply any associated policies.
policies.
Even more importantly, the client instance proving possession of a Even more importantly, the client instance proving possession of a
key on the first request allows the AS to associate future requests key on the first request allows the AS to associate future requests
with each other by binding all future requests in that transaction to with each other by binding all future requests in that transaction to
the same key. The access token used for grant continuation is bound the same key. The access token used for grant continuation is bound
to the same key and proofing mechanism used by the client instance in to the same key and proofing mechanism used by the client instance in
its initial request, which means that the client instance needs to its initial request; this means that the client instance needs to
prove possession of that same key in future requests allowing the AS prove possession of that same key in future requests, which allows
to be sure that the same client instance is executing the follow-ups the AS to be sure that the same client instance is executing the
for a given ongoing grant request. Therefore, the AS has to ensure follow-ups for a given ongoing grant request. Therefore, the AS has
that all subsequent requests for a grant are associated with the same to ensure that all subsequent requests for a grant are associated
key that started the grant, or the most recent rotation of that key. with the same key that started the grant or with the most recent
This need holds true even if the initial key is previously unknown to rotation of that key. This need holds true even if the initial key
the AS, such as would be the case when a client instance creates an is previously unknown to the AS, such as would be the case when a
ephemeral key for its request. Without this ongoing association, an client instance creates an ephemeral key for its request. Without
attacker would be able to impersonate a client instance in the midst this ongoing association, an attacker would be able to impersonate a
of a grant request, potentially stealing access tokens and subject client instance in the midst of a grant request, potentially stealing
information with impunity. access tokens and subject information with impunity.
Additionally, all access tokens in GNAP default to be associated with Additionally, all access tokens in GNAP default to be associated with
the key that was presented during the grant request that created the the key that was presented during the grant request that created the
access token. This association allows an RS to know that the access token. This association allows an RS to know that the
presenter of the access token is the same party that the token was presenter of the access token is the same party that the token was
issued to, as identified by their keys. While non-bound bearer issued to, as identified by their keys. While non-bound bearer
tokens are an option in GNAP, these types of tokens have their own tokens are an option in GNAP, these types of tokens have their own
tradeoffs discussed in Section 13.9. trade-offs, which are discussed in Section 11.9.
TLS functions at the transport layer, ensuring that only the parties TLS functions at the transport layer, ensuring that only the parties
on either end of that connection can read the information passed on either end of that connection can read the information passed
along that connection. Each time a new connection is made, such as along that connection. Each time a new connection is made, such as
for a new HTTP request, a new trust is re-established that is mostly for a new HTTP request, a new trust that is mostly unrelated to
unrelated to previous connections. While modern TLS does make use of previous connections is re-established. While modern TLS does make
session resumption, this still needs to be augmented with use of session resumption, this still needs to be augmented with
authentication methods to determine the identity of parties on the authentication methods to determine the identity of parties on the
connections. In other words, it is not possible with TLS alone to connections. In other words, it is not possible with TLS alone to
know that the same party is making a set of calls over time, since know that the same party is making a set of calls over time, since
each time a new TLS connection is established, both the client and each time a new TLS connection is established, both the client and
the server (or the server only when using Section 7.3.2) have to the server (or the server only when using MTLS (Section 7.3.2)) have
validate the other party's identity. Such a verification can be to validate the other party's identity. Such a verification can be
achieved via methods described in [RFC9525], but these are not enough achieved via methods described in [RFC9525], but these are not enough
to establish the identity of the client instance in many cases. to establish the identity of the client instance in many cases.
To counter this, GNAP defines a set of key binding methods in To counter this, GNAP defines a set of key binding methods in
Section 7.3 that allow authentication and proof of possession by the Section 7.3 that allows authentication and proof of possession by the
caller, which is usually the client instance. These methods are caller, which is usually the client instance. These methods are
intended to be used in addition to TLS on all connections. intended to be used in addition to TLS on all connections.
13.3. MTLS Message Integrity 11.3. MTLS Message Integrity
The MTLS key proofing mechanism (Section 7.3.2) provides a means for The MTLS key proofing mechanism (Section 7.3.2) provides a means for
a client instance to present a key using a certificate at the TLS a client instance to present a key using a certificate at the TLS
layer. Since TLS protects the entire HTTP message in transit, layer. Since TLS protects the entire HTTP message in transit,
verification of the TLS client certificate presented with the message verification of the TLS client certificate presented with the message
provides a sufficient binding between the two. However, since TLS is provides a sufficient binding between the two. However, since TLS is
functioning at a separate layer from HTTP, there is no direct functioning at a separate layer from HTTP, there is no direct
connection between the TLS key presentation and the message itself, connection between the TLS key presentation and the message itself,
other than the fact that the message was presented over the TLS other than the fact that the message was presented over the TLS
channel. That is to say, any HTTP message can be presented over the channel. That is to say, any HTTP message can be presented over the
TLS channel in question with the same level of trust. The verifier TLS channel in question with the same level of trust. The verifier
is responsible for ensuring the key in the TLS client certificate is is responsible for ensuring the key in the TLS client certificate is
the one expected for a particular request. For example, if the the one expected for a particular request. For example, if the
request is a grant request (Section 2), the AS needs to compare the request is a grant request (Section 2), the AS needs to compare the
TLS client certificate presented at the TLS layer to the key TLS client certificate presented at the TLS layer to the key
identified in the request content itself (either by value or through identified in the request content itself (either by value or through
a referenced identifier). a referenced identifier).
Furthermore, the prevalence of the TLS-terminating reverse proxy Furthermore, the prevalence of the TLS terminating reverse proxy
(TTRP) pattern in deployments adds a wrinkle to the situation. In (TTRP) pattern in deployments adds a wrinkle to the situation. In
this common pattern, the TTRP validates the TLS connection and then this common pattern, the TTRP validates the TLS connection and then
forwards the HTTP message contents onward to an internal system for forwards the HTTP message contents onward to an internal system for
processing. The system processing the HTTP message no longer has processing. The system processing the HTTP message no longer has
access to the original TLS connection's information and context. To access to the original TLS connection's information and context. To
compensate for this, the TTRP could inject the TLS client certificate compensate for this, the TTRP could inject the TLS client certificate
into the forwarded request as a header parameter using [RFC9111], into the forwarded request using the HTTP Client-Cert header field
giving the downstream system access to the certificate information. [RFC9111], giving the downstream system access to the certificate
The TTRP has to be trusted to provide accurate certificate information. The TTRP has to be trusted to provide accurate
information, and the connection between the TTRP and the downstream certificate information, and the connection between the TTRP and the
system also has to be protected. The TTRP could provide some downstream system also has to be protected. The TTRP could provide
additional assurance, for example, by adding its own signature to the some additional assurance, for example, by adding its own signature
Client-Cert header field using [RFC9421]. This signature would be to the Client-Cert header field using HTTP message signatures
effectively ignored by GNAP (since it would not use GNAP's tag [RFC9421]. This signature would be effectively ignored by GNAP
parameter value) but would be understood by the downstream service as (since it would not use GNAP's tag parameter value) but would be
part of its deployment. understood by the downstream service as part of its deployment.
Additional considerations for different types of deployment patterns Additional considerations for different types of deployment patterns
and key distribution mechanisms for MTLS are found in Section 13.4. and key distribution mechanisms for MTLS are found in Section 11.4.
13.4. MTLS Deployment Patterns 11.4. MTLS Deployment Patterns
GNAP does not specify how a client instance's keys could be made GNAP does not specify how a client instance's keys could be made
known to the AS ahead of time. Public Key Infrastructure (PKI) can known to the AS ahead of time. The Public Key Infrastructure (PKI)
be used to manage the keys used by client instances when calling the can be used to manage the keys used by client instances when calling
AS, allowing the AS to trust a root key from a trusted authority. the AS, allowing the AS to trust a root key from a trusted authority.
This method is particularly relevant to the MTLS key proofing method, This method is particularly relevant to the MTLS key proofing method,
where the client instance presents its certificate to the AS as part where the client instance presents its certificate to the AS as part
of the TLS connection. An AS using PKI to validate the MTLS of the TLS connection. An AS using PKI to validate the MTLS
connection would need to ensure that the presented certificate was connection would need to ensure that the presented certificate was
issued by a trusted certificate authority before allowing the issued by a trusted certificate authority before allowing the
connection to continue. PKI-based certificates would allow a key to connection to continue. PKI-based certificates would allow a key to
be revoked and rotated through management at the certificate be revoked and rotated through management at the certificate
authority without requiring additional registration or management at authority without requiring additional registration or management at
the AS. The PKI required to manage mutually-authenticated TLS has the AS. The PKI required to manage mutually authenticated TLS has
historically been difficult to deploy, especially at scale, but it historically been difficult to deploy, especially at scale, but it
remains an appropriate solution for systems where the required remains an appropriate solution for systems where the required
management overhead is not an impediment. management overhead is not an impediment.
MTLS in GNAP need not use a PKI backing, as self-signed certificates MTLS in GNAP need not use a PKI backing, as self-signed certificates
and certificates from untrusted authorities can still be presented as and certificates from untrusted authorities can still be presented as
part of a TLS connection. In this case, the verifier would validate part of a TLS connection. In this case, the verifier would validate
the connection but accept whatever certificate was presented by the the connection but accept whatever certificate was presented by the
client software. This specific certificate can then be bound to all client software. This specific certificate can then be bound to all
future connections from that client software by being bound to the future connections from that client software by being bound to the
resulting access tokens, in a trust-on-first-use pattern. See resulting access tokens, in a trust-on-first-use pattern. See
Section 13.3 for more considerations on MTLS as a key proofing Section 11.3 for more considerations on MTLS as a key proofing
mechanism. mechanism.
13.5. Protection of Client Instance Key Material 11.5. Protection of Client Instance Key Material
Client instances are identified by their unique keys, and anyone with Client instances are identified by their unique keys, and anyone with
access to a client instance's key material will be able to access to a client instance's key material will be able to
impersonate that client instance to all parties. This is true for impersonate that client instance to all parties. This is true for
both calls to the AS as well as calls to an RS using an access token both calls to the AS as well as calls to an RS using an access token
bound to the client instance's unique key. As a consequence, it is bound to the client instance's unique key. As a consequence, it is
of utmost importance for a client instance to protect its private key of utmost importance for a client instance to protect its private key
material. material.
Different types of client software have different methods for Different types of client software have different methods for
creating, managing, and registering keys. GNAP explicitly allows for creating, managing, and registering keys. GNAP explicitly allows for
ephemeral clients such as single-page applications (SPAs) and single- ephemeral clients such as single-page applications (SPAs) and single-
user clients (such as mobile applications) to create and present user clients (such as mobile applications) to create and present
their own keys during the initial grant request without any explicit their own keys during the initial grant request without any explicit
pre-registration step. The client software can securely generate a pre-registration step. The client software can securely generate a
keypair on-device and present the public key, along with proof of key pair on the device and present the public key, along with proof
holding the associated private key, to the AS as part of the initial of holding the associated private key, to the AS as part of the
request. To facilitate trust in these ephemeral keys, GNAP further initial request. To facilitate trust in these ephemeral keys, GNAP
allows for an extensible set of client information to be passed with further allows for an extensible set of client information to be
the request. This information can include device posture and third- passed with the request. This information can include device posture
party attestations of the client software's provenance and and third-party attestations of the client software's provenance and
authenticity, depending on the needs and capabilities of the client authenticity, depending on the needs and capabilities of the client
software and its deployment. software and its deployment.
From GNAP's perspective, each distinct key is a different client From GNAP's perspective, each distinct key is a different client
instance. However, multiple client instances can be grouped together instance. However, multiple client instances can be grouped together
by an AS policy and treated similarly to each other. For instance, by an AS policy and treated similarly to each other. For instance,
if an AS knows of several different keys for different servers within if an AS knows of several different keys for different servers within
a cluster, the AS can decide that authorization of one of these a cluster, the AS can decide that authorization of one of these
servers applies to all other servers within the cluster. An AS that servers applies to all other servers within the cluster. An AS that
chooses to do this needs to be careful with how it groups different chooses to do this needs to be careful with how it groups different
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Additionally, if an end user controls multiple instances of a single Additionally, if an end user controls multiple instances of a single
type of client software, such as having an application installed on type of client software, such as having an application installed on
multiple devices, each of these instances is expected to have a multiple devices, each of these instances is expected to have a
separate key and be issued separate access tokens. However, if the separate key and be issued separate access tokens. However, if the
AS is able to group these separate instances together as described AS is able to group these separate instances together as described
above, it can streamline the authorization process for new instances above, it can streamline the authorization process for new instances
of the same client software. For example, if two client instances of the same client software. For example, if two client instances
can present proof of a valid installation of a piece of client can present proof of a valid installation of a piece of client
software, the AS would be able to associate the approval of the first software, the AS would be able to associate the approval of the first
instance of this software to all related instances. The AS could instance of this software to all related instances. The AS could
then choose to bypass an explicit prompt of the resource owner for then choose to bypass an explicit prompt of the RO for approval
approval during authorization, since such approval has already been during authorization, since such approval has already been given. An
given. An AS doing such a process would need to take assurance AS doing such a process would need to take assurance measures that
measures that the different instances are in fact correlated and the different instances are in fact correlated and authentic, as well
authentic, as well as ensuring the expected resource owner is in as ensure that the expected RO is in control of the client instance.
control of the client instance.
Finally, if multiple instances of client software each have the same Finally, if multiple instances of client software each have the same
key, then from GNAP's perspective, these are functionally the same key, then from GNAP's perspective, these are functionally the same
client instance as GNAP has no reasonable way to differentiate client instance as GNAP has no reasonable way to differentiate
between them. This situation could happen if multiple instances between them. This situation could happen if multiple instances
within a cluster can securely share secret information among within a cluster can securely share secret information among
themselves. Even though there are multiple copies of the software, themselves. Even though there are multiple copies of the software,
the shared key makes these copies all present as a single instance. the shared key makes these copies all present as a single instance.
It is considered bad practice to share keys between copies of It is considered bad practice to share keys between copies of
software unless they are very tightly integrated with each other and software unless they are very tightly integrated with each other and
can be closely managed. It is particularly bad practice to allow an can be closely managed. It is particularly bad practice to allow an
end user to copy keys between client instances and to willingly use end user to copy keys between client instances and to willingly use
the same key in multiple instances. the same key in multiple instances.
13.6. Protection of Authorization Server 11.6. Protection of Authorization Server
The AS performs critical functions in GNAP, including authenticating The AS performs critical functions in GNAP, including authenticating
client software, managing interactions with end users to gather client software, managing interactions with end users to gather
consent and provide notice, and issuing access tokens for client consent and provide notice, and issuing access tokens for client
instances to present to resource servers. As such, protecting the AS instances to present to RSs. As such, protecting the AS is central
is central to any GNAP deployment. to any GNAP deployment.
If an attacker is able to gain control over an AS, they would be able If an attacker is able to gain control over an AS, they would be able
to create fraudulent tokens and manipulate registration information to create fraudulent tokens and manipulate registration information
to allow for malicious clients. These tokens and clients would be to allow for malicious clients. These tokens and clients would be
trusted by other components in the ecosystem under the protection of trusted by other components in the ecosystem under the protection of
the AS. the AS.
If the AS is using signed access tokens, an attacker in control of If the AS uses signed access tokens, an attacker in control of the
the AS's signing keys would be able to manufacture fraudulent tokens AS's signing keys would be able to manufacture fraudulent tokens for
for use at RS's under the protection of the AS. use at RSs under the protection of the AS.
If an attacker is able to impersonate an AS, they would be able to If an attacker is able to impersonate an AS, they would be able to
trick legitimate client instances into making signed requests for trick legitimate client instances into making signed requests for
information which could potentially be proxied to a real AS. To information that could potentially be proxied to a real AS. To
combat this, all communications to the AS need to be made over TLS or combat this, all communications to the AS need to be made over TLS or
its equivalent, and the software making the connection has to its equivalent, and the software making the connection has to
validate the certificate chain of the host it is connecting to. validate the certificate chain of the host it is connecting to.
Consequently, protecting, monitoring, and auditing the AS is Consequently, protecting, monitoring, and auditing the AS is
paramount to preserving the security of a GNAP-protected ecosystem. paramount to preserving the security of a GNAP-protected ecosystem.
The AS presents attackers with a valuable target for attack. The AS presents attackers with a valuable target for attack.
Fortunately, the core focus and function of the AS is to provide Fortunately, the core focus and function of the AS is to provide
security for the ecosystem, unlike the RS whose focus is to provide security for the ecosystem, unlike the RS whose focus is to provide
an API or the client software whose focus is to access the API. an API or the client software whose focus is to access the API.
13.7. Symmetric and Asymmetric Client Instance Keys 11.7. Symmetric and Asymmetric Client Instance Keys
Many of the cryptographic methods used by GNAP for key-proofing can Many of the cryptographic methods used by GNAP for key proofing can
support both asymmetric and symmetric cryptography, and can be support both asymmetric and symmetric cryptography, and they can be
extended to use a wide variety of mechanisms. Implementers will find extended to use a wide variety of mechanisms. Implementors will find
useful the available guidelines on cryptographic key management the available guidelines on cryptographic key management provided in
provided in [RFC4107]. While symmetric cryptographic systems have [RFC4107] useful. While symmetric cryptographic systems have some
some benefits in speed and simplicity, they have a distinct drawback benefits in speed and simplicity, they have a distinct drawback --
that both parties need access to the same key in order to do both both parties need access to the same key in order to do both signing
signing and verification of the message. When more than two parties and verification of the message. When more than two parties share
share the same symmetric key, data origin authentication is not the same symmetric key, data origin authentication is not provided.
provided. Any party that knows the symmetric key can compute a valid Any party that knows the symmetric key can compute a valid MAC;
MAC; therefore, the contents could originate from any one of the therefore, the contents could originate from any one of the parties.
parties.
Use of symmetric cryptography means that when the client instance Use of symmetric cryptography means that when the client instance
calls the AS to request a token, the AS needs to know the exact value calls the AS to request a token, the AS needs to know the exact value
of the client instance's key (or be able to derive it) in order to of the client instance's key (or be able to derive it) in order to
validate the key proof signature. With asymmetric keys, the client validate the key proof signature. With asymmetric keys, the client
needs only to send its public key to the AS to allow for verification needs to only send its public key to the AS to allow for verification
that the client holds the associated private key, regardless of that the client holds the associated private key, regardless of
whether that key was pre-registered or not with the AS. whether or not that key was pre-registered with the AS.
Symmetric keys also have the expected advantage of providing better Symmetric keys also have the expected advantage of providing better
protection against quantum threats in the future. Also, these types protection against quantum threats in the future. Also, these types
of keys (and their secure derivations) are widely supported among of keys (and their secure derivations) are widely supported among
many cloud-based key management systems. many cloud-based key management systems.
When used to bind to an access token, a key value must be known by When used to bind to an access token, a key value must be known by
the RS in order to validate the proof signature on the request. the RS in order to validate the proof signature on the request.
Common methods for communicating these proofing keys include putting Common methods for communicating these proofing keys include putting
information in a structured access token and allowing the RS to look information in a structured access token and allowing the RS to look
up the associated key material against the value of the access token. up the associated key material against the value of the access token.
With symmetric cryptography, both of these methods would expose the With symmetric cryptography, both of these methods would expose the
signing key to the RS, and in the case of an structured access token, signing key to the RS and, in the case of a structured access token,
potentially to any party that can see the access token itself unless potentially to any party that can see the access token itself unless
the token's payload has been encrypted. Any of these parties would the token's payload has been encrypted. Any of these parties would
then be able to make calls using the access token by creating a valid then be able to make calls using the access token by creating a valid
signature using the shared key. With asymmetric cryptography, the RS signature using the shared key. With asymmetric cryptography, the RS
needs to know only the public key associated with the token in order needs to only know the public key associated with the token in order
to validate the request, and therefore the RS cannot create any new to validate the request; therefore, the RS cannot create any new
signed calls. signed calls.
While both signing approaches are allowed, GNAP treats these two While both signing approaches are allowed, GNAP treats these two
classes of keys somewhat differently. Only the public portion of classes of keys somewhat differently. Only the public portion of
asymmetric keys are allowed to be sent by value in requests to the AS asymmetric keys are allowed to be sent by value in requests to the AS
when establishing a connection. Since sending a symmetric key (or when establishing a connection. Since sending a symmetric key (or
the private portion of an asymmetric key) would expose the signing the private portion of an asymmetric key) would expose the signing
material to any parties on the request path, including any attackers, material to any parties on the request path, including any attackers,
sending these kinds of keys by value is prohibited. Symmetric keys sending these kinds of keys by value is prohibited. Symmetric keys
can still be used by client instances, but only if the client can still be used by client instances, but only if the client
instance can send a reference to the key and not its value. This instance can send a reference to the key and not its value. This
approach allows the AS to use pre-registered symmetric keys as well approach allows the AS to use pre-registered symmetric keys as well
as key derivation schemes to take advantage of symmetric cryptography as key derivation schemes to take advantage of symmetric cryptography
but without requiring key distribution at runtime, which would expose without requiring key distribution at runtime, which would expose the
the keys in transit. keys in transit.
Both the AS and client software can use systems such as hardware Both the AS and client software can use systems such as hardware
security modules to strengthen their key security storage and security modules to strengthen their key security storage and
generation for both asymmetric and symmetric keys (see also generation for both asymmetric and symmetric keys (see also
Section 7.1.2). Section 7.1.2).
13.8. Generation of Access Tokens 11.8. Generation of Access Tokens
The content of access tokens need to be such that only the generating The contents of access tokens need to be such that only the
AS would be able to create them, and the contents cannot be generating AS would be able to create them, and the contents cannot
manipulated by an attacker to gain different or additional access be manipulated by an attacker to gain different or additional access
rights. rights.
One method for accomplishing this is to use a cryptographically One method for accomplishing this is to use a cryptographically
random value for the access token, generated by the AS using a secure random value for the access token, generated by the AS using a secure
randomization function with sufficiently high entropy. The odds of randomization function with sufficiently high entropy. The odds of
an attacker guessing the output of the randomization function to an attacker guessing the output of the randomization function to
collide with a valid access token are exceedingly small, and even collide with a valid access token are exceedingly small, and even
then the attacker would not have any control over what the access then, the attacker would not have any control over what the access
token would represent since that information would be held close by token would represent since that information would be held close by
the AS. the AS.
Another method for accomplishing this is to use a structured token Another method for accomplishing this is to use a structured token
that is cryptographically signed. In this case, the payload of the that is cryptographically signed. In this case, the payload of the
access token declares to the RS what the token is good for, but the access token declares to the RS what the token is good for, but the
signature applied by the AS during token generation covers this signature applied by the AS during token generation covers this
payload. Only the AS can create such a signature and therefore only payload. Only the AS can create such a signature; therefore, only
the AS can create such a signed token. The odds of an attacker being the AS can create such a signed token. The odds of an attacker being
able to guess a signature value with a useful payload are exceedingly able to guess a signature value with a useful payload are exceedingly
small. This technique only works if all targeted RS's check the small. This technique only works if all targeted RSs check the
signature of the access token. Any RS that does not validate the signature of the access token. Any RS that does not validate the
signature of all presented tokens would be susceptible to injection signature of all presented tokens would be susceptible to injection
of a modified or falsified token. Furthermore, an AS has to of a modified or falsified token. Furthermore, an AS has to
carefully protect the keys used to sign access tokens, since anyone carefully protect the keys used to sign access tokens, since anyone
with access to these signing keys would be able to create seemingly- with access to these signing keys would be able to create seemingly
valid access tokens using them. valid access tokens using them.
13.9. Bearer Access Tokens 11.9. Bearer Access Tokens
Bearer access tokens can be used by any party that has access to the Bearer access tokens can be used by any party that has access to the
token itself, without any additional information. As a natural token itself, without any additional information. As a natural
consequence, any RS that a bearer token is presented to has the consequence, any RS that a bearer token is presented to has the
technical capability of presenting that bearer token to another RS, technical capability of presenting that bearer token to another RS,
as long as the token is valid. It also means that any party that is as long as the token is valid. It also means that any party that is
able capture of the token value in storage or in transit is able to able to capture the token value in storage or in transit is able to
use the access token. While bearer tokens are inherently simpler, use the access token. While bearer tokens are inherently simpler,
this simplicity has been misapplied and abused in making needlessly this simplicity has been misapplied and abused in making needlessly
insecure systems. The downsides of bearer tokens have become more insecure systems. The downsides of bearer tokens have become more
pertinent lately as stronger authentication systems have caused some pertinent lately as stronger authentication systems have caused some
attacks to shift to target tokens and APIs. attacks to shift to target tokens and APIs.
In GNAP, key-bound access tokens are the default due to their higher In GNAP, key-bound access tokens are the default due to their higher
security properties. While bearer tokens can be used in GNAP, their security properties. While bearer tokens can be used in GNAP, their
use should be limited to cases where the simplicity benefits outweigh use should be limited to cases where the simplicity benefits outweigh
the significant security downsides. One common deployment pattern is the significant security downsides. One common deployment pattern is
to use a gateway that takes in key-bound tokens on the outside, and to use a gateway that takes in key-bound tokens on the outside and
verifies the signatures on the incoming requests, but translates the verifies the signatures on the incoming requests but translates the
requests to a bearer token for use by trusted internal systems. The requests to a bearer token for use by trusted internal systems. The
bearer tokens are never issued or available outside of the internal bearer tokens are never issued or available outside of the internal
systems, greatly limiting the exposure of the less secure tokens but systems, greatly limiting the exposure of the less-secure tokens but
allowing the internal deployment to benefit from the advantages of allowing the internal deployment to benefit from the advantages of
bearer tokens. bearer tokens.
13.10. Key-Bound Access Tokens 11.10. Key-Bound Access Tokens
Key-bound access tokens, as the name suggests, are bound to a Key-bound access tokens, as the name suggests, are bound to a
specific key and must be presented along with proof of that key specific key and must be presented along with proof of that key
during use. The key itself is not presented at the same time as the during use. The key itself is not presented at the same time as the
token, so even if a token value is captured, it cannot be used to token, so even if a token value is captured, it cannot be used to
make a new request. This is particularly true for an RS, which will make a new request. This is particularly true for an RS, which will
see the token value but will not see the keys used to make the see the token value but will not see the keys used to make the
request (assuming asymmetric cryptography is in use, see request (assuming asymmetric cryptography is in use, see
Section 13.7). Section 11.7).
Key-bound access tokens provide this additional layer of protection Key-bound access tokens provide this additional layer of protection
only when the RS checks the signature of the message presented with only when the RS checks the signature of the message presented with
the token. Acceptance of an invalid presentation signature, or the token. Acceptance of an invalid presentation signature, or
failure to check the signature entirely, would allow an attacker to failure to check the signature entirely, would allow an attacker to
make calls with a captured access token without having access to the make calls with a captured access token without having access to the
related signing key material. related signing key material.
In addition to validating the signature of the presentation message In addition to validating the signature of the presentation message
itself, the RS also needs to ensure that the signing key used is itself, the RS also needs to ensure that the signing key used is
appropriate for the presented token. If an RS does not ensure that appropriate for the presented token. If an RS does not ensure that
the right keys were used to sign a message with a specific token, an the right keys were used to sign a message with a specific token, an
attacker would be able to capture an access token and sign the attacker would be able to capture an access token and sign the
request with their own keys, thereby negating the benefits of using request with their own keys, thereby negating the benefits of using
key-bound access tokens. key-bound access tokens.
The RS also needs to ensure that sufficient portions of the message The RS also needs to ensure that sufficient portions of the message
are covered by the signature. Any items outside the signature could are covered by the signature. Any items outside the signature could
still affect the API's processing decisions, but these items would still affect the API's processing decisions, but these items would
not be strongly bound to the token presentation. As such, an not be strongly bound to the token presentation. As such, an
attacker could capture a valid request, then manipulate portions of attacker could capture a valid request and then manipulate portions
the request outside of the signature envelope in order to cause of the request outside of the signature envelope in order to cause
unwanted actions at the protected API. unwanted actions at the protected API.
Some key-bound tokens are susceptible to replay attacks, depending on Some key-bound tokens are susceptible to replay attacks, depending on
the details of the signing method used. Key proofing mechanisms used the details of the signing method used. Therefore, key proofing
with access tokens therefore need to use replay protection mechanisms mechanisms used with access tokens need to use replay-protection
covered under the signature such as a per-message nonce, a reasonably mechanisms covered under the signature such as a per-message nonce, a
short time validity window, or other uniqueness constraints. The reasonably short time validity window, or other uniqueness
details of using these will vary depending on the key proofing constraints. The details of using these will vary depending on the
mechanism in use, but for example, HTTP Message Signatures has both a key proofing mechanism in use. For example, HTTP message signatures
created and nonce signature parameter as well as the ability to cover have both a created and nonce signature parameter as well as the
significant portions of the HTTP message. All of these can be used ability to cover significant portions of the HTTP message. All of
to limit the attack surface. these can be used to limit the attack surface.
13.11. Exposure of End-user Credentials to Client Instance 11.11. Exposure of End-User Credentials to Client Instance
As a delegation protocol, one of the main goals of GNAP is to prevent As a delegation protocol, one of the main goals of GNAP is to prevent
the client software from being exposed to any credentials or the client software from being exposed to any credentials or
information about the end user or resource owner as a requirement of information about the end user or RO as a requirement of the
the delegation process. By using the variety of interaction delegation process. By using the variety of interaction mechanisms,
mechanisms, the resource owner can interact with the AS without ever the RO can interact with the AS without ever authenticating to the
authenticating to the client software, and without the client client software and without the client software having to impersonate
software having to impersonate the resource owner through replay of the RO through replay of their credentials.
their credentials.
Consequently, no interaction methods defined in the GNAP core require Consequently, no interaction methods defined in this specification
the end user to enter their credentials, but it is technologically require the end user to enter their credentials, but it is
possible for an extension to be defined to carry such values. Such technologically possible for an extension to be defined to carry such
an extension would be dangerous as it would allow rogue client values. Such an extension would be dangerous as it would allow rogue
software to directly collect, store, and replay the end user's client software to directly collect, store, and replay the end user's
credentials outside of any legitimate use within a GNAP request. credentials outside of any legitimate use within a GNAP request.
The concerns of such an extension could be mitigated through use of a The concerns of such an extension could be mitigated through use of a
challenge and response unlocked by the end user's credentials. For challenge and response unlocked by the end user's credentials. For
example, the AS presents a challenge as part of an interaction start example, the AS presents a challenge as part of an interaction start
method, and the client instance signs that challenge using a key method, and the client instance signs that challenge using a key
derived from a password presented by the end user. It would be derived from a password presented by the end user. It would be
possible for the client software to collect this password in a secure possible for the client software to collect this password in a secure
software enclave without exposing the password to the rest of the software enclave without exposing the password to the rest of the
client software or putting it across the wire to the AS. The AS can client software or putting it across the wire to the AS. The AS can
validate this challenge response against a known password for the validate this challenge response against a known password for the
identified end user. While an approach such as this does not remove identified end user. While an approach such as this does not remove
all of the concerns surrounding such a password-based scheme, it is all of the concerns surrounding such a password-based scheme, it is
at least possible to implement in a more secure fashion than simply at least possible to implement in a more secure fashion than simply
collecting and replaying the password. Even so, such schemes should collecting and replaying the password. Even so, such schemes should
only ever be used by trusted clients due to the ease of abusing them. only ever be used by trusted clients due to the ease of abusing them.
13.12. Mixing Up Authorization Servers 11.12. Mixing Up Authorization Servers
If a client instance is able to work with multiple AS's If a client instance is able to work with multiple ASes
simultaneously, it is possible for an attacker to add a compromised simultaneously, it is possible for an attacker to add a compromised
AS to the client instance's configuration and cause the client AS to the client instance's configuration and cause the client
software to start a request at the compromised AS. This AS could software to start a request at the compromised AS. This AS could
then proxy the client's request to a valid AS in order to attempt to then proxy the client's request to a valid AS in order to attempt to
get the resource owner to approve access for the legitimate client get the RO to approve access for the legitimate client instance.
instance.
A client instance needs to always be aware of which AS it is talking A client instance needs to always be aware of which AS it is talking
to throughout a grant process, and ensure that any callback for one to throughout a grant process and ensure that any callback for one AS
AS does not get conflated with the callback to different AS. The does not get conflated with the callback to different AS. The
interaction finish hash calculation in Section 4.2.3 allows a client interaction finish hash calculation in Section 4.2.3 allows a client
instance to protect against this kind of substitution, but only if instance to protect against this kind of substitution, but only if
the client instance validates the hash. If the client instance does the client instance validates the hash. If the client instance does
not use an interaction finish method or does not check the not use an interaction finish method or does not check the
interaction finish hash value, the compromised AS can be granted a interaction finish hash value, the compromised AS can be granted a
valid access token on behalf of the resource owner. See valid access token on behalf of the RO. See Sections 4.5.5 and 5.5
[AXELAND2021] for details of one such attack, which has been since of [AXELAND2021] for details of one such attack, which has been
addressed in this document by including the grant endpoint in the addressed in this document by including the grant endpoint in the
interaction hash calculation. Note that the client instance still interaction hash calculation. Note that the client instance still
needs to validate the hash for the attack to be prevented. needs to validate the hash for the attack to be prevented.
13.13. Processing of Client-Presented User Information 11.13. Processing of Client-Presented User Information
GNAP allows the client instance to present assertions and identifiers GNAP allows the client instance to present assertions and identifiers
of the current user to the AS as part of the initial request. This of the current user to the AS as part of the initial request. This
information should only ever be taken by the AS as a hint, since the information should only ever be taken by the AS as a hint, since the
AS has no way to tell if the represented person is present at the AS has no way to tell if the represented person is present at the
client software, without using an interaction mechanism. This client software without using an interaction mechanism. This
information does not guarantee the given user is there, but it does information does not guarantee the given user is there, but it does
constitute a statement by the client software that the AS can take constitute a statement by the client software that the AS can take
into account. into account.
For example, if a specific user is claimed to be present prior to For example, if a specific user is claimed to be present prior to
interaction, but a different user is shown to be present during interaction, but a different user is shown to be present during
interaction, the AS can either determine this to be an error or interaction, the AS can either determine this to be an error or
signal to the client instance through returned subject information signal to the client instance through returned subject information
that the current user has changed from what the client instance that the current user has changed from what the client instance
thought. This user information can also be used by the AS to thought. This user information can also be used by the AS to
streamline the interaction process when the user is present. For streamline the interaction process when the user is present. For
example, instead of having the user type in their account identifier example, instead of having the user type in their account identifier
during interaction at a redirected URI, the AS can immediately during interaction at a redirected URI, the AS can immediately
challenge the user for their account credentials. Alternatively, if challenge the user for their account credentials. Alternatively, if
an existing session is detected, the AS can determine that it matches an existing session is detected, the AS can determine that it matches
the identifier provided by the client and subsequently skip an the identifier provided by the client and subsequently skip an
explicit authentication event by the resource owner. explicit authentication event by the RO.
In cases where the AS trusts the client software more completely, due In cases where the AS trusts the client software more completely, due
to policy or by previous approval of a given client instance, the AS to policy or previous approval of a given client instance, the AS can
can take this user information as a statement that the user is take this user information as a statement that the user is present
present and could issue access tokens and release subject information and could issue access tokens and release subject information without
without interaction. The AS should only take such action in very interaction. The AS should only take such action in very limited
limited circumstances, as a client instance could assert whatever it circumstances, as a client instance could assert whatever it likes
likes for the user's identifiers in its request. The AS can limit for the user's identifiers in its request. The AS can limit the
the possibility of this by issuing randomized opaque identifiers to possibility of this by issuing randomized opaque identifiers to
client instances to represent different end user accounts after an client instances to represent different end-user accounts after an
initial login. initial login.
When a client instance presents an assertion to the AS, the AS needs When a client instance presents an assertion to the AS, the AS needs
to evaluate that assertion. Since the AS is unlikely to be the to evaluate that assertion. Since the AS is unlikely to be the
intended audience of an assertion held by the client software, the AS intended audience of an assertion held by the client software, the AS
will need to evaluate the assertion in a different context. Even in will need to evaluate the assertion in a different context. Even in
this case, the AS can still evaluate that the assertion was generated this case, the AS can still evaluate that the assertion was generated
by a trusted party, was appropriately signed, and is within any time by a trusted party, was appropriately signed, and is within any time
validity windows stated by the assertion. If the client instance's validity windows stated by the assertion. If the client instance's
audience identifier is known to the AS and can be associated with the audience identifier is known to the AS and can be associated with the
client instance's presented key, the AS can also evaluate that the client instance's presented key, the AS can also evaluate that the
appropriate client instance is presenting the claimed assertion. All appropriate client instance is presenting the claimed assertion. All
of this will prevent an attacker from presenting a manufactured of this will prevent an attacker from presenting a manufactured
assertion, or one captured from an untrusted system. However, assertion or one captured from an untrusted system. However, without
without validating the audience of the assertion, a captured validating the audience of the assertion, a captured assertion could
assertion could be presented by the client instance to impersonate a be presented by the client instance to impersonate a given end user.
given end user. In such cases, the assertion offers little more In such cases, the assertion offers little more protection than a
protection than a simple identifier would. simple identifier would.
A special case exists where the AS is the generator of the assertion A special case exists where the AS is the generator of the assertion
being presented by the client instance. In these cases, the AS can being presented by the client instance. In these cases, the AS can
validate that it did issue the assertion and it is associated with validate that it did issue the assertion and it is associated with
the client instance presenting the assertion. the client instance presenting the assertion.
13.14. Client Instance Pre-registration 11.14. Client Instance Pre-registration
Each client instance is identified by its own unique key, and for Each client instance is identified by its own unique key, and for
some kinds of client software such as a web server or backend system, some kinds of client software such as a web server or backend system,
this identification can be facilitated by registering a single key this identification can be facilitated by registering a single key
for a piece of client software ahead of time. This registration can for a piece of client software ahead of time. This registration can
be associated with a set of display attributes to be used during the be associated with a set of display attributes to be used during the
authorization process, identifying the client software to the user. authorization process to identify the client software to the user.
In these cases, it can be assumed that only one instance of client In these cases, it can be assumed that only one instance of client
software will exist, likely to serve many different users. software will exist, likely to serve many different users.
A client's registration record needs to include its identifying key. A client's registration record needs to include its identifying key.
Furthermore, it is the case that any clients using symmetric Furthermore, it is the case that any clients using symmetric
cryptography for key proofing mechanisms need to have their keys pre- cryptography for key proofing mechanisms need to have their keys pre-
registered. The registration should also include any information registered. The registration should also include any information
that would aid in the authorization process, such as a display name that would aid in the authorization process, such as a display name
and logo. The registration record can also limit a given client to and logo. The registration record can also limit a given client to
ask for certain kinds of information and access, or be limited to ask for certain kinds of information or use specific interaction
specific interaction mechanisms at runtime. mechanisms at runtime.
It also is sensible to pre-register client instances when the It also is sensible to pre-register client instances when the
software is acting autonomously, without the need for a runtime software is acting autonomously, without the need for a runtime
approval by a resource owner or any interaction with an end user. In approval by a RO or any interaction with an end user. In these
these cases, an AS needs to rest on the trust decisions that have cases, an AS needs to rely on the trust decisions that have been
been determined prior to runtime in determining what rights and determined prior to runtime to determine what rights and tokens to
tokens to grant to a given client instance. grant to a given client instance.
However, it does not make sense to pre-register many types of However, it does not make sense to pre-register many types of
clients. Single-page applications (SPAs) and mobile/desktop clients. Single-page applications (SPAs) and mobile/desktop
applications in particular present problems with pre-registration. applications in particular present problems with pre-registration.
For SPAs, the instances are ephemeral in nature and long-term For SPAs, the instances are ephemeral in nature, and long-term
registration of a single instance leads to significant storage and registration of a single instance leads to significant storage and
management overhead at the AS. For mobile applications, each management overhead at the AS. For mobile applications, each
installation of the client software is a separate instance, and installation of the client software is a separate instance, and
sharing a key among all instances would be detrimental to security as sharing a key among all instances would be detrimental to security as
the compromise of any single installation would compromise all copies the compromise of any single installation would compromise all copies
for all users. for all users.
An AS can treat these classes of client software differently from An AS can treat these classes of client software differently from
each other, perhaps by allowing access to certain high-value APIs each other, perhaps by allowing access to certain high-value APIs
only to pre-registered known clients, or by requiring an active end only to pre-registered known clients or by requiring an active end-
user delegation of authority to any client software not pre- user delegation of authority to any client software not pre-
registered. registered.
An AS can also provide warnings and caveats to resource owners during An AS can also provide warnings and caveats to ROs during the
the authorization process, allowing the user to make an informed authorization process, allowing the user to make an informed decision
decision regarding the software they are authorizing. For example, regarding the software they are authorizing. For example, if the AS
if the AS has done vetting of the client software and this specific has vetted the client software and this specific instance, it can
instance, it can present a different authorization screen compared to present a different authorization screen compared to a client
a client instance that is presenting all of its information at instance that is presenting all of its information at runtime.
runtime.
Finally, an AS can use platform attestations and other signals from Finally, an AS can use platform attestations and other signals from
the client instance at runtime to determine whether the software the client instance at runtime to determine whether or not the
making the request is legitimate or not. The details of such software making the request is legitimate. The details of such
attestations are outside the scope of the core protocol, but the attestations are outside the scope of this specification, but the
client portion of a grant request provides a natural extension point client portion of a grant request provides a natural extension point
to such information through the Client Instance Fields registry to such information through the "GNAP Client Instance Fields"
(Section 11.7). registry (Section 10.7).
13.15. Client Instance Impersonation 11.15. Client Instance Impersonation
If client instances are allowed to set their own user-facing display If client instances are allowed to set their own user-facing display
information, such as a display name and website URL, a malicious information, such as a display name and website URL, a malicious
client instance could impersonate legitimate client software for the client instance could impersonate legitimate client software for the
purposes of tricking users into authorizing the malicious client. purposes of tricking users into authorizing the malicious client.
Requiring clients to pre-register does not fully mitigate this Requiring clients to pre-register does not fully mitigate this
problem since many pre-registration systems have self-service portals problem since many pre-registration systems have self-service portals
for management of client registration, allowing authenticated for management of client registration, allowing authenticated
developers to enter self-asserted information into the management developers to enter self-asserted information into the management
portal. portal.
An AS can mitigate this by actively filtering all self-asserted An AS can mitigate this by actively filtering all self-asserted
values presented by client software, both dynamically as part of GNAP values presented by client software, both dynamically as part of GNAP
and through a registration portal, to limit the kinds of and through a registration portal, to limit the kinds of
impersonation that would be done. impersonation that could be done.
An AS can also warn the resource owner about the provenance of the An AS can also warn the RO about the provenance of the information it
information it is displaying, allowing the resource owner to make a is displaying, allowing the RO to make a more informed delegation
more informed delegation decision. For example, an AS can visually decision. For example, an AS can visually differentiate between a
differentiate between a client instance that can be traced back to a client instance that can be traced back to a specific developer's
specific developer's registration and an instance that has self- registration and an instance that has self-asserted its own display
asserted its own display information. information.
13.16. Client-Hosted Logo URI 11.16. Client-Hosted Logo URI
The logo_uri client display field defined in Section 2.3.2 allows the The logo_uri client display field defined in Section 2.3.2 allows the
client instance to specify a URI from which an image can be fetched client instance to specify a URI from which an image can be fetched
for display during authorization decisions. When the URI points to for display during authorization decisions. When the URI points to
an externally hosted resource (as opposed to a data: URI), the an externally hosted resource (as opposed to a data: URI), the
logo_uri field presents challenges in addition to the considerations logo_uri field presents challenges in addition to the considerations
in Section 13.15. in Section 11.15.
When a logo_uri is externally hosted, the client software (or the When a logo_uri is externally hosted, the client software (or the
host of the asset) can change the contents of the logo without host of the asset) can change the contents of the logo without
informing the AS. Since the logo is considered an aspect of the informing the AS. Since the logo is considered an aspect of the
client software's identity, this flexibility allows for a more client software's identity, this flexibility allows for a more
dynamically-managed client instance that makes use of the distributed dynamically managed client instance that makes use of the distributed
systems. systems.
However, this same flexibility allows the host of the asset to change However, this same flexibility allows the host of the asset to change
the hosted file in a malicious way, such as replacing the image the hosted file in a malicious way, such as replacing the image
content with malicious software for download or imitating a different content with malicious software for download or imitating a different
piece of client software. Additionally, the act of fetching the URI piece of client software. Additionally, the act of fetching the URI
could accidentally leak information to the image host in the HTTP could accidentally leak information to the image host in the HTTP
Referer header field, if one is sent. Even though GNAP intentionally Referer header field, if one is sent. Even though GNAP intentionally
does not include security parameters in front-channel URI's wherever does not include security parameters in front-channel URIs wherever
possible, the AS still should take steps to ensure that this possible, the AS still should take steps to ensure that this
information does not leak accidentally, such as setting a referrer information does not leak accidentally, such as setting a referrer
policy on image links or displaying images only from paged served policy on image links or displaying images only from pages served
from a URI with no sensitive security or identity information. from a URI with no sensitive security or identity information.
To avoid these issues, the AS can insist on the use of data: URIs, To avoid these issues, the AS can insist on the use of data: URIs,
though that might not be practical for all types of client software. though that might not be practical for all types of client software.
Alternatively, the AS could pre-fetch the content of the URI and Alternatively, the AS could pre-fetch the content of the URI and
present its own copy to the resource owner instead. This practice present its own copy to the RO instead. This practice opens the AS
opens the AS to potential SSRF attacks, as discussed in to potential SSRF attacks, as discussed in Section 11.34.
Section 13.34.
13.17. Interception of Information in the Browser 11.17. Interception of Information in the Browser
Most information passed through the web-browser is susceptible to Most information passed through the web browser is susceptible to
interception and possible manipulation by elements within the browser interception and possible manipulation by elements within the browser
such as scripts loaded within pages. Information in the URI is such as scripts loaded within pages. Information in the URI is
exposed through browser and server logs, and can also leak to other exposed through browser and server logs, and it can also leak to
parties through HTTP Referer headers. other parties through HTTP Referer headers.
GNAP's design limits the information passed directly through the GNAP's design limits the information passed directly through the
browser, allowing for opaque URIs in most circumstances. For the browser, allowing for opaque URIs in most circumstances. For the
redirect-based interaction finish mechanism, named query parameters redirect-based interaction finish mechanism, named query parameters
are used to carry unguessable opaque values. For these, GNAP are used to carry unguessable opaque values. For these, GNAP
requires creation and validation of a cryptographic hash to protect requires creation and validation of a cryptographic hash to protect
the query parameters added to the URI and associate them with an the query parameters added to the URI and associate them with an
ongoing grant process and values not passed in the URI. The client ongoing grant process and values not passed in the URI. The client
instance has to properly validate this hash to prevent an attacker instance has to properly validate this hash to prevent an attacker
from injecting an interaction reference intended for a different AS from injecting an interaction reference intended for a different AS
or client instance. or client instance.
Several interaction start mechanisms use URIs created by the AS and Several interaction start mechanisms use URIs created by the AS and
passed to the client instance. While these URIs are opaque to the passed to the client instance. While these URIs are opaque to the
client instance, it's possible for the AS to include parameters, client instance, it's possible for the AS to include parameters,
paths, and other pieces of information that could leak security data paths, and other pieces of information that could leak security data
or be manipulated by a party in the middle of the transaction. An AS or be manipulated by a party in the middle of the transaction. An AS
implementation can avoid this problem by creating URIs using implementation can avoid this problem by creating URIs using
unguessable values that are randomized for each new grant request. unguessable values that are randomized for each new grant request.
13.18. Callback URI Manipulation 11.18. Callback URI Manipulation
The callback URI used in interaction finish mechanisms is defined by The callback URI used in interaction finish mechanisms is defined by
the client instance. This URI is opaque to the AS, but can contain the client instance. This URI is opaque to the AS but can contain
information relevant to the client instance's operations. In information relevant to the client instance's operations. In
particular, the client instance can include state information to particular, the client instance can include state information to
allow the callback request to be associated with an ongoing grant allow the callback request to be associated with an ongoing grant
request. request.
Since this URI is exposed to the end user's browser, it is Since this URI is exposed to the end user's browser, it is
susceptible to both logging and manipulation in transit before the susceptible to both logging and manipulation in transit before the
request is made to the client software. As such, a client instance request is made to the client software. As such, a client instance
should never put security-critical or private information into the should never put security-critical or private information into the
callback URI in a cleartext form. For example, if the client callback URI in a cleartext form. For example, if the client
software includes a post-redirect target URI in its callback URI to software includes a post-redirect target URI in its callback URI to
the AS, this target URI could be manipulated by an attacker, creating the AS, this target URI could be manipulated by an attacker, creating
an open redirector at the client. Instead, a client instance can use an open redirector at the client. Instead, a client instance can use
an unguessable identifier in the URI that can then be used by the an unguessable identifier in the URI that can then be used by the
client software to look up the details of the pending request. Since client software to look up the details of the pending request. Since
this approach requires some form of statefulness by the client this approach requires some form of statefulness by the client
software during the redirection process, clients that are not capable software during the redirection process, clients that are not capable
of holding state through a redirect should not use redirect-based of holding state through a redirect should not use redirect-based
interaction mechanisms. interaction mechanisms.
13.19. Redirection Status Codes 11.19. Redirection Status Codes
As already described in [I-D.ietf-oauth-security-topics], a server As described in [OAUTH-SEC-TOPICS], a server should never use HTTP
should never use the HTTP 307 status code to redirect a request that status code 307 (Temporary Redirect) to redirect a request that
potentially contains user credentials. If an HTTP redirect is used potentially contains user credentials. If an HTTP redirect is used
for such a request, the HTTP status code 303 "See Other" should be for such a request, HTTP status code 303 (See Other) should be used
used instead. instead.
The status code 307, as defined in the HTTP standard [HTTP], requires Status code 307 (Temporary Redirect), as defined in the HTTP standard
the user agent to preserve the method and content of a request, thus [HTTP], requires the user agent to preserve the method and content of
submitting the content of the POST request to the redirect target. a request, thus submitting the content of the POST request to the
In the HTTP standard [HTTP], only the status code 303 unambiguously redirect target. In the HTTP standard [HTTP], only status code 303
enforces rewriting the HTTP POST request to an HTTP GET request, (See Other) unambiguously enforces rewriting the HTTP POST request to
which eliminates the POST content from the redirected request. For an HTTP GET request, which eliminates the POST content from the
all other status codes, including status code 302, user agents are redirected request. For all other status codes, including status
allowed not to rewrite a POST request into a GET request and thus to code 302 (Found), user agents are allowed to keep a redirected POST
resubmit the contents. request as a POST and thus can resubmit the content.
The use of status code 307 results in a vulnerability when using the The use of status code 307 (Temporary Redirect) results in a
redirect interaction finish method (Section 3.3.5). With this vulnerability when using the redirect interaction finish method
method, the AS potentially prompts the RO to enter their credentials (Section 3.3.5). With this method, the AS potentially prompts the RO
in a form that is then submitted back to the AS (using an HTTP POST to enter their credentials in a form that is then submitted back to
request). The AS checks the credentials and, if successful, may the AS (using an HTTP POST request). The AS checks the credentials
directly redirect the RO to the client instance's redirect URI. Due and, if successful, may immediately redirect the RO to the client
to the use of status code 307, the RO's user agent now transmits the instance's redirect URI. Due to the use of status code 307
RO's credentials to the client instance. A malicious client instance (Temporary Redirect), the RO's user agent now transmits the RO's
can then use the obtained credentials to impersonate the RO at the credentials to the client instance. A malicious client instance can
AS. then use the obtained credentials to impersonate the RO at the AS.
Redirection away from the initial URI in an interaction session could Redirection away from the initial URI in an interaction session could
also leak information found in that initial URI through the HTTP also leak information found in that initial URI through the HTTP
Referer header field, which would be sent by the user agent to the Referer header field, which would be sent by the user agent to the
redirect target. To avoid such leakage, a server can first redirect redirect target. To avoid such leakage, a server can first redirect
to an internal interstitial page without any identifying or sensitive to an internal interstitial page without any identifying or sensitive
information on the URI before processing the request. When the user information on the URI before processing the request. When the user
agent is ultimately redirected from this page, no part of the agent is ultimately redirected from this page, no part of the
original interaction URI will be found in the Referer header. original interaction URI will be found in the Referer header.
13.20. Interception of Responses from the AS 11.20. Interception of Responses from the AS
Responses from the AS contain information vital to both the security Responses from the AS contain information vital to both the security
and privacy operations of GNAP. This information includes nonces and privacy operations of GNAP. This information includes nonces
used in cryptographic calculations, subject identifiers, assertions, used in cryptographic calculations, Subject Identifiers, assertions,
public keys, and information about what client software is requesting public keys, and information about what client software is requesting
and was granted. and was granted.
In addition, if bearer tokens are used or keys are issued alongside a In addition, if bearer tokens are used or keys are issued alongside a
bound access token, the response from the AS contains all information bound access token, the response from the AS contains all information
necessary for use of the contained access token. Any party that is necessary for use of the contained access token. Any party that is
capable of viewing such a response, such as an intermediary proxy, capable of viewing such a response, such as an intermediary proxy,
would be able to exfiltrate and use this token. If the access token would be able to exfiltrate and use this token. If the access token
is instead bound to the client instance's presented key, is instead bound to the client instance's presented key,
intermediaries no longer have sufficient information to use the intermediaries no longer have sufficient information to use the
token. They can still, however, gain information about the end user token. They can still, however, gain information about the end user
as well as the actions of the client software. as well as the actions of the client software.
13.21. Key Distribution 11.21. Key Distribution
GNAP does not define ways for the client instances keys to be GNAP does not define ways for the client instances keys to be
provided to the client instances, particularly in light of how those provided to the client instances, particularly in light of how those
keys are made known to the AS. These keys could be generated keys are made known to the AS. These keys could be generated
dynamically on the client software or pre-registered at the AS in a dynamically on the client software or pre-registered at the AS in a
static developer portal. The keys for client instances could also be static developer portal. The keys for client instances could also be
distributed as part of the deployment process of instances of the distributed as part of the deployment process of instances of the
client software. For example, an application installation framework client software. For example, an application installation framework
could generate a keypair for each copy of client software, then both could generate a key pair for each copy of client software and then
install it into the client software upon installation and registering both install it into the client software upon installation and
that instance with the AS. register that instance with the AS.
Alternatively, it's possible for the AS to generate keys to be used Alternatively, it's possible for the AS to generate keys to be used
with access tokens that are separate from the keys used by the client with access tokens that are separate from the keys used by the client
instance to request tokens. In this method, the AS would generate instance to request tokens. In this method, the AS would generate
the asymmetric keypair or symmetric key and return the public key or the asymmetric key pair or symmetric key and return the public key or
key reference, to the client instance alongside the access token key reference to the client instance alongside the access token
itself. The means for the AS to return generated key values to the itself. The means for the AS to return generated key values to the
client instance are out of scope, since GNAP does not allow the client instance are out of scope, since GNAP does not allow the
transmission of private or shared key information within the protocol transmission of private or shared key information within the protocol
itself. itself.
Additionally, if the token is bound to a key other than the client Additionally, if the token is bound to a key other than the client
instance's presented key, this opens a possible attack surface for an instance's presented key, this opens a possible attack surface for an
attacker's AS to request an access token then substitute their own attacker's AS to request an access token and then substitute their
key material in the response to the client instance. The attacker's own key material in the response to the client instance. The
AS would need to be able to use the same key as the client instance, attacker's AS would need to be able to use the same key as the client
but this setup would allow an attacker's AS to make use of a instance, but this setup would allow an attacker's AS to make use of
compromised key within a system. This attack can be prevented by a compromised key within a system. This attack can be prevented by
only binding access tokens to the client instance's presented keys, only binding access tokens to the client instance's presented keys
and by having client instances have a strong association between and by having client instances have a strong association between
which keys they expect to use and the AS they expect to use them on. which keys they expect to use and the AS they expect to use them on.
This attack is also only able to be propagated on client instances This attack is also only able to be propagated on client instances
that talk to more than one AS at runtime, which can be limited by the that talk to more than one AS at runtime, which can be limited by the
client software. client software.
13.22. Key Rotation Policy 11.22. Key Rotation Policy
When keys are rotated, there could be a delay in the propagation of When keys are rotated, there could be a delay in the propagation of
that rotation to various components in the AS's ecosystem. The AS that rotation to various components in the AS's ecosystem. The AS
can define its own policy regarding the timeout of the previously- can define its own policy regarding the timeout of the previously
bound key, either making it immediately obsolete or allowing for a bound key, either making it immediately obsolete or allowing for a
limited grace period during which both the previously-bound key and limited grace period during which both the previously bound key and
the current key can be used for signing requests. Such a grace the current key can be used for signing requests. Such a grace
period can be useful when there are multiple running copies of the period can be useful when there are multiple running copies of the
client that are coordinated with each other. For example, the client client that are coordinated with each other. For example, the client
software could be deployed as a cloud service with multiple software could be deployed as a cloud service with multiple
orchestrated nodes. Each of these copies is deployed using the same orchestrated nodes. Each of these copies is deployed using the same
key and therefore all the nodes represent the same client instance to key; therefore, all the nodes represent the same client instance to
the AS. In such cases, it can be difficult, or even impossible, to the AS. In such cases, it can be difficult, or even impossible, to
update the keys on all these copies in the same instant. update the keys on all these copies in the same instant.
The need for accommodating such known delays in the system needs to The need to accommodate such known delays in the system needs to be
be balanced with the risk of allowing an old key to still be used. balanced with the risk of allowing an old key to still be used.
Narrowly restricting the exposure opportunities for exploit at the AS Narrowly restricting the exposure opportunities for exploit at the AS
in terms of time, place, and method makes exploit significantly more in terms of time, place, and method makes exploit significantly more
difficult, especially if the exception happens only once. For difficult, especially if the exception happens only once. For
example, the AS can reject requests from the previously-bound key (or example, the AS can reject requests from the previously bound key (or
any previous one before it) to cause rotation to a new key, or at any previous one before it) to cause rotation to a new key or at
least ensure that the rotation happens in an idempotent way to the least ensure that the rotation happens in an idempotent way to the
same new key. same new key.
See also the related considerations for token values in See also the related considerations for token values in
Section 13.33. Section 11.33.
13.23. Interaction Finish Modes and Polling 11.23. Interaction Finish Modes and Polling
During the interaction process, the client instance usually hands During the interaction process, the client instance usually hands
control of the user experience over to another component, be it the control of the user experience over to another component, be it the
system browser, another application, or some action the resource system browser, another application, or some action the RO is
owner is instructed to take on another device. By using an instructed to take on another device. By using an interaction finish
interaction finish method, the client instance can be securely method, the client instance can be securely notified by the AS when
notified by the AS when the interaction is completed and the next the interaction is completed and the next phase of the protocol
phase of the protocol should occur. This process includes should occur. This process includes information that the client
information that the client instance can use to validate the finish instance can use to validate the finish call from the AS and prevent
call from the AS and prevent some injection, session hijacking, and some injection, session hijacking, and phishing attacks.
phishing attacks.
Some types of client deployment are unable to receive an interaction Some types of client deployment are unable to receive an interaction
finish message. Without an interaction finish method to notify it, finish message. Without an interaction finish method to notify it,
the client instance will need to poll the grant continuation API the client instance will need to poll the grant continuation API
while waiting for the resource owner to approve or deny the request. while waiting for the RO to approve or deny the request. An attacker
An attacker could take advantage of this situation by capturing the could take advantage of this situation by capturing the interaction
interaction start parameters and phishing a legitimate user into start parameters and phishing a legitimate user into authorizing the
authorizing the attacker's waiting client instance, which would in attacker's waiting client instance, which would in turn have no way
turn have no way of associating the completed interaction from the of associating the completed interaction from the targeted user with
targeted user with the start of the request from the attacker. the start of the request from the attacker.
However, it is important to note that this pattern is practically However, it is important to note that this pattern is practically
indistinguishable from some legitimate use cases. For example, a indistinguishable from some legitimate use cases. For example, a
smart device emits a code for the resource owner to enter on a smart device emits a code for the RO to enter on a separate device.
separate device. The smart device has to poll because the expected The smart device has to poll because the expected behavior is that
behavior is that the interaction will take place on the separate the interaction will take place on the separate device, without a way
device, without a way to return information to the original device's to return information to the original device's context.
context.
As such, developers need to weigh the risks of forgoing an As such, developers need to weigh the risks of forgoing an
interaction finish method against the deployment capabilities of the interaction finish method against the deployment capabilities of the
client software and its environment. Due to the increased security, client software and its environment. Due to the increased security,
an interaction finish method should be employed whenever possible. an interaction finish method should be employed whenever possible.
13.24. Session Management for Interaction Finish Methods 11.24. Session Management for Interaction Finish Methods
When using an interaction finish method such as redirect or push, the When using an interaction finish method such as redirect or push, the
client instance receives an unsolicited inbound request from an client instance receives an unsolicited inbound request from an
unknown party over HTTPS. The client instance needs to be able to unknown party over HTTPS. The client instance needs to be able to
successfully associate this incoming request with a specific pending successfully associate this incoming request with a specific pending
grant request being managed by the client instance. If the client grant request being managed by the client instance. If the client
instance is not careful and precise about this, an attacker could instance is not careful and precise about this, an attacker could
associate their own session at the client instance with a stolen associate their own session at the client instance with a stolen
interaction response. The means of preventing this varies by the interaction response. The means of preventing this vary by the type
type of client software and interaction methods in use. Some common of client software and interaction methods in use. Some common
patterns are enumerated here. patterns are enumerated here.
If the end user interacts with the client instance through a web If the end user interacts with the client instance through a web
browser and the redirect interaction finish method is used, the browser and the redirect interaction finish method is used, the
client instance can ensure that the incoming HTTP request from the client instance can ensure that the incoming HTTP request from the
finish method is presented in the same browser session that the grant finish method is presented in the same browser session that the grant
request was started in. This technique is particularly useful when request was started in. This technique is particularly useful when
the redirect interaction start mode is used as well, since in many the redirect interaction start mode is used as well, since in many
cases the end user will follow the redirection with the same browser cases, the end user will follow the redirection with the same browser
that they are using to interact with the client instance. The client that they are using to interact with the client instance. The client
instance can then store the relevant pending grant information in the instance can then store the relevant pending grant information in the
session, either in the browser storage directly (such as with a session, either in the browser storage directly (such as with a
single-page application) or in an associated session store on a back- single-page application) or in an associated session store on a
end server. In both cases, when the incoming request reaches the backend server. In both cases, when the incoming request reaches the
client instance, the session information can be used to ensure that client instance, the session information can be used to ensure that
the same party that started the request is present as the request the same party that started the request is present as the request
finishes. finishes.
Ensuring that the same party that started a request is present when Ensuring that the same party that started a request is present when
that request finishes can prevent phishing attacks, where an attacker that request finishes can prevent phishing attacks, where an attacker
starts a request at an honest client instance and tricks an honest RO starts a request at an honest client instance and tricks an honest RO
into authorizing it. For example, if an honest end user (that also into authorizing it. For example, if an honest end user (that also
acts as the RO) wants to start a request through a client instance acts as the RO) wants to start a request through a client instance
controlled by the attacker, the attacker can start a request at an controlled by the attacker, the attacker can start a request at an
honest client instance and then redirect the honest end user to the honest client instance and then redirect the honest end user to the
interaction URI from the attackers session with the honest client interaction URI from the attackers session with the honest client
instance. If the honest end user then fails to realize that they are instance. If the honest end user then fails to realize that they are
not authorizing the attacker-controlled client instance (with which not authorizing the attacker-controlled client instance (with which
it started its request) but instead the honest client instance when it started its request) but instead the honest client instance when
interacting with the AS, the attacker's session with the honest interacting with the AS, the attacker's session with the honest
client instance would be authorized. This would give the attacker client instance would be authorized. This would give the attacker
access to the honest end user's resources that the honest client access to the honest end user's resources that the honest client
instance is authorized to access. However, if after the interaction instance is authorized to access. However, if after the interaction,
the AS redirects the honest end user back to the client instance the AS redirects the honest end user back to the client instance
whose grant request the end user just authorized, the honest end user whose grant request the end user just authorized, the honest end user
is redirected to the honest client instance. The honest client is redirected to the honest client instance. The honest client
instance can then detect that the end user is not the party that instance can then detect that the end user is not the party that
started the request, since the request at the honest client instance started the request, since the request at the honest client instance
was started by the attacker. This detection can prevent the attack. was started by the attacker. This detection can prevent the attack.
This is related to the discussion in Section 13.15, because again the This is related to the discussion in Section 11.15, because again the
attack can be prevented by the AS informing the user as much as attack can be prevented by the AS informing the user as much as
possible about the client instance that is to be authorized. possible about the client instance that is to be authorized.
If the end user does not interact with the client instance through a If the end user does not interact with the client instance through a
web browser or the interaction start method does not use the same web browser or the interaction start method does not use the same
browser or device that the end user is interacting through (such as browser or device that the end user is interacting through (such as
the launch of a second device through a scannable code or the launch of a second device through a scannable code or
presentation of a user code) the client instance will not be able to presentation of a user code), the client instance will not be able to
strongly associate an incoming HTTP request with an established strongly associate an incoming HTTP request with an established
session with the end user. This is also true when the push session with the end user. This is also true when the push
interaction finish method is used, since the HTTP request comes interaction finish method is used, since the HTTP request comes
directly from the interaction component of the AS. In these directly from the interaction component of the AS. In these
circumstances, the client instance can at least ensure that the circumstances, the client instance can at least ensure that the
incoming HTTP request can be uniquely associated with an ongoing incoming HTTP request can be uniquely associated with an ongoing
grant request by making the interaction finish callback URI unique grant request by making the interaction finish callback URI unique
for the grant when making the interaction request (Section 2.5.2). for the grant when making the interaction request (Section 2.5.2).
Mobile applications and other client instances that generally serve Mobile applications and other client instances that generally serve
only a single end user at a time can use this unique incoming URL to only a single end user at a time can use this unique incoming URL to
differentiate between a legitimate incoming request and an attacker's differentiate between a legitimate incoming request and an attacker's
stolen request. stolen request.
13.25. Calculating Interaction Hash 11.25. Calculating Interaction Hash
While the use of GNAP's signing mechanisms and token-protected grant While the use of GNAP's signing mechanisms and token-protected grant
API provides significant security protections to the protocol, the API provides significant security protections to the protocol, the
interaction reference mechanism is susceptible to monitoring, interaction reference mechanism is susceptible to monitoring,
capture, and injection by an attacker. To combat this, GNAP requires capture, and injection by an attacker. To combat this, GNAP requires
the calculation and verification of an interaction hash. A client the calculation and verification of an interaction hash. A client
instance might be tempted to skip this step, but doing so leaves the instance might be tempted to skip this step, but doing so leaves the
client instance open to injection and manipulation by an attacker client instance open to injection and manipulation by an attacker
that could lead to additional issues. that could lead to additional issues.
skipping to change at page 188, line 32 skipping to change at line 8358
| | | | | | | | | | | | | | | |
| +==(E)================================>| | | +==(E)================================>| |
| | | | | | | | | | | | | | | |
| |<=(7)=+ | | | | | | |<=(7)=+ | | | | |
| | | | | | | | | | | | | | | |
| +==(F)================>| | | | | +==(F)================>| | | |
| | | | | +-(G)->| | | | | | | +-(G)->| |
| | | | | | | | | | | | | | | |
`----` `------` +--------+ +--------+ `----` `------` +--------+ +--------+
Figure 11: Figure 11: Interaction hash attack Figure 11: Interaction Hash Attack
* Prerequisites: The client instance can allow multiple end users to Prerequisites: The client instance can allow multiple end users to
access the same AS. The attacker is attempting to associate their access the same AS. The attacker is attempting to associate their
rights with the target user's session. rights with the target user's session.
* (1) The attacker starts a session at the client instance. * (1) The attacker starts a session at the client instance.
* (2) The client instance creates a grant request with nonce CN1. * (2) The client instance creates a grant request with nonce CN1.
* (3) The AS responds to the grant request with a need to interact, * (3) The AS responds to the grant request with a need to interact,
nonce SN1, and a continuation token, CT1. nonce SN1, and a continuation token, CT1.
* (4) The client instructs the attacker to interact at the AS. * (4) The client instructs the attacker to interact at the AS.
* (5) The attacker interacts at the AS. * (5) The attacker interacts at the AS.
* (6) The AS completes the interact finish with interact ref IR1 and * (6) The AS completes the interact finish with interact reference
interact hash IH1 calculated from (CN1 + SN1 + IR1 + AS). The IR1 and interact hash IH1 calculated from (CN1 + SN1 + IR1 + AS).
attacker prevents IR1 from returning to the client instance. The attacker prevents IR1 from returning to the client instance.
* (A) The target user starts a session at the client instance. * (A) The target user starts a session at the client instance.
* (B) The client instance creates a grant request with nonce CN2. * (B) The client instance creates a grant request with nonce CN2.
* (C) The AS responds to the grant request with a need to interact, * (C) The AS responds to the grant request with a need to interact,
nonce SN2, and a continuation token, CT2. nonce SN2, and a continuation token, CT2.
* (D) The client instance instructs the user to interact at the AS. * (D) The client instance instructs the user to interact at the AS.
* (E) The target user interacts at the AS. * (E) The target user interacts at the AS.
* (7) Before the target user can complete their interaction, the * (7) Before the target user can complete their interaction, the
attacker delivers their own interact ref IR1 into the user's attacker delivers their own interact reference IR1 into the user's
session. The attacker cannot calculate the appropriate hash session. The attacker cannot calculate the appropriate hash
because the attacker does not have access to CN2 and SN2. because the attacker does not have access to CN2 and SN2.
* (F) The target user triggers the interaction finish in their own * (F) The target user triggers the interaction finish in their own
session with the attacker's IR1. session with the attacker's IR1.
* (G) If the client instance is checking the interaction hash, the * (G) If the client instance is checking the interaction hash, the
attack stops here because the hash calculation of (CN2 + SN2 + IR1 attack stops here because the hash calculation of (CN2 + SN2 + IR1
+ AS) will fail. If the client instance does not check the + AS) will fail. If the client instance does not check the
interaction hash, the client instance will be tricked into interaction hash, the client instance will be tricked into
submitting the interaction reference to the AS. Here, the AS will submitting the interaction reference to the AS. Here, the AS will
reject the interaction request because it is presented against CT2 reject the interaction request because it is presented against CT2
and not CT1 as expected. However, an attacker who has potentially and not CT1 as expected. However, an attacker who has potentially
injected CT1 as the value of CT2 would be able to continue the injected CT1 as the value of CT2 would be able to continue the
attack. attack.
Even with additional checks in place, client instances using Even with additional checks in place, client instances using
interaction finish mechanisms are responsible for checking the interaction finish mechanisms are responsible for checking the
interaction hash to provide security to the overall system. interaction hash to provide security to the overall system.
13.26. Storage of Information During Interaction and Continuation 11.26. Storage of Information during Interaction and Continuation
When starting an interactive grant request, a client application has When starting an interactive grant request, a client application has
a number of protocol elements that it needs to manage, including a number of protocol elements that it needs to manage, including
nonces, references, keys, access tokens, and other elements. During nonces, references, keys, access tokens, and other elements. During
the interaction process, the client instance usually hands control of the interaction process, the client instance usually hands control of
the user experience over to another component, be it the system the user experience over to another component, be it the system
browser, another application, or some action the resource owner is browser, another application, or some action the RO is instructed to
instructed to take on another device. In order for the client take on another device. In order for the client instance to make its
instance to make its continuation call, it will need to recall all of continuation call, it will need to recall all of these protocol
these protocol elements at a future time. Usually this means the elements at a future time. Usually, this means the client instance
client instance will need to store these protocol elements in some will need to store these protocol elements in some retrievable
retrievable fashion. fashion.
If the security protocol elements are stored on the end user's If the security protocol elements are stored on the end user's
device, such as in browser storage or in local application data device, such as in browser storage or in local application data
stores, capture and exfiltration of this information could allow an stores, capture and exfiltration of this information could allow an
attacker to continue a pending transaction instead of the client attacker to continue a pending transaction instead of the client
instance. Client software can make use of secure storage mechanisms, instance. Client software can make use of secure storage mechanisms,
including hardware-based key and data storage, to prevent such including hardware-based key and data storage, to prevent such
exfiltration. exfiltration.
Note that in GNAP, the client instance has to choose its interaction Note that in GNAP, the client instance has to choose its interaction
finish URI prior to making the first call to the AS. As such, the finish URI prior to making the first call to the AS. As such, the
interaction finish URI will often have a unique identifier for the interaction finish URI will often have a unique identifier for the
ongoing request, allowing the client instance to access the correct ongoing request, allowing the client instance to access the correct
portion of its storage. Since this URI is passed to other parties portion of its storage. Since this URI is passed to other parties
and often used through a browser, this URI should not contain any and often used through a browser, this URI should not contain any
security-sensitive information that would be valuable to an attacker, security-sensitive information that would be valuable to an attacker,
such as any token identifier, nonce, or user information. Instead, a such as any token identifier, nonce, or user information. Instead, a
cryptographically random value is suggested, and that value should be cryptographically random value is suggested, and that value should be
used to index into a secure session or storage mechanism. used to index into a secure session or storage mechanism.
13.27. Denial of Service (DoS) through Grant Continuation 11.27. Denial of Service (DoS) through Grant Continuation
When a client instance starts off an interactive process, it will When a client instance starts off an interactive process, it will
eventually need to continue the grant request in a subsequent message eventually need to continue the grant request in a subsequent message
to the AS. It's possible for a naive client implementation to to the AS. It's possible for a naive client implementation to
continuously send continuation requests to the AS while waiting for continuously send continuation requests to the AS while waiting for
approval, especially if no interaction finish method is used. Such approval, especially if no interaction finish method is used. Such
constant requests could overwhelm the AS's ability to respond to both constant requests could overwhelm the AS's ability to respond to both
these and other requests. these and other requests.
To mitigate this for well-behaved client software, the continuation To mitigate this for well-behaved client software, the continuation
response contains a wait parameter that is intended to tell the response contains a wait parameter that is intended to tell the
client instance how long it should wait until making its next client instance how long it should wait until making its next
request. This value can be used to back off client software that is request. This value can be used to back off client software that is
checking too quickly by returning increasing wait times for a single checking too quickly by returning increasing wait times for a single
client instance. client instance.
If client software ignores the wait value and makes its continuation If client software ignores the wait value and makes its continuation
calls too quickly, or if the client software assumes the absence of calls too quickly or if the client software assumes the absence of
the wait values means it should poll immediately, the AS can choose the wait values means it should poll immediately, the AS can choose
to return errors to the offending client instance, including possibly to return errors to the offending client instance, including possibly
canceling the ongoing grant request. With well-meaning client canceling the ongoing grant request. With well-meaning client
software these errors can indicate a need to change the client software, these errors can indicate a need to change the client
software's programmed behavior. software's programmed behavior.
13.28. Exhaustion of Random Value Space 11.28. Exhaustion of Random Value Space
Several parts of the GNAP process make use of unguessable randomized Several parts of the GNAP process make use of unguessable randomized
values, such as nonces, tokens, user codes, and randomized URIs. values, such as nonces, tokens, user codes, and randomized URIs.
Since these values are intended to be unique, a sufficiently powerful Since these values are intended to be unique, a sufficiently powerful
attacker could make a large number of requests to trigger generation attacker could make a large number of requests to trigger generation
of randomized values in an attempt to exhaust the random number of randomized values in an attempt to exhaust the random number
generation space. While this attack is particularly applicable to generation space. While this attack is particularly applicable to
the AS, client software could likewise be targeted by an attacker the AS, client software could likewise be targeted by an attacker
triggering new grant requests against an AS. triggering new grant requests against an AS.
To mitigate this, software can ensure that its random values are To mitigate this, software can ensure that its random values are
chosen from a significantly large pool that exhaustion of that pool chosen from a significantly large pool so that exhaustion of that
is prohibitive for an attacker. Additionally, the random values can pool is prohibitive for an attacker. Additionally, the random values
be time-boxed in such a way as their validity windows are reasonably can be time-boxed in such a way that their validity windows are
short. Since many of the random values used within GNAP are used reasonably short. Since many of the random values used within GNAP
within limited portions of the protocol, it is reasonable for a are used within limited portions of the protocol, it is reasonable
particular random value to be valid for only a small amount of time. for a particular random value to be valid for only a small amount of
For example, the nonces used for interaction finish hash calculation time. For example, the nonces used for interaction finish hash
need only to be valid while the client instance is waiting for the calculation need only to be valid while the client instance is
finish callback and can be functionally expired when the interaction waiting for the finish callback and can be functionally expired when
has completed. Similarly, artifacts like access tokens and the the interaction has completed. Similarly, artifacts like access
interaction reference can be limited to have lifetimes tied to their tokens and the interaction reference can be limited to have lifetimes
functional utility. Finally, each different category of artifact tied to their functional utility. Finally, each different category
(nonce, token, reference, identifier, etc.) can be generated from a of artifact (nonce, token, reference, identifier, etc.) can be
separate random pool of values instead of a single global value generated from a separate random pool of values instead of a single
space. global value space.
13.29. Front-channel URIs 11.29. Front-Channel URIs
Some interaction methods in GNAP make use of URIs accessed through Some interaction methods in GNAP make use of URIs accessed through
the end user's browser, known collectively as front-channel the end user's browser, known collectively as front-channel
communication. These URIs are most notably present in the redirect communication. These URIs are most notably present in the redirect
interaction start method and the redirect interaction finish mode. interaction start method and the redirect interaction finish mode.
Since these URIs are intended to be given to the end user, the end Since these URIs are intended to be given to the end user, the end
user and their browser will be subjected to anything hosted at that user and their browser will be subjected to anything hosted at that
URI including viruses, malware, and phishing scams. This kind of URI including viruses, malware, and phishing scams. This kind of
risk is inherent to all redirection-based protocols, including GNAP risk is inherent to all redirection-based protocols, including GNAP,
when used in this way. when used in this way.
When talking to a new or unknown AS, a client instance might want to When talking to a new or unknown AS, a client instance might want to
check the URI from the interaction start against a blocklist and warn check the URI from the interaction start against a blocklist and warn
the end user before redirecting them. Many client instances will the end user before redirecting them. Many client instances will
provide an interstitial message prior to redirection in order to provide an interstitial message prior to redirection in order to
prepare the user for control of the user experience being handed to prepare the user for control of the user experience being handed to
the domain of the AS, and such a method could be used to warn the the domain of the AS, and such a method could be used to warn the
user of potential threats. For instance, a rogue AS impersonating a user of potential threats (for instance, a rogue AS impersonating a
well-known service provider. Client software can also prevent this well-known service provider). Client software can also prevent this
by managing an allowlist of known and trusted AS's. by managing an allowlist of known and trusted ASes.
Alternatively, an attacker could start a GNAP request with a known Alternatively, an attacker could start a GNAP request with a known
and trusted AS but include their own attack site URI as the callback and trusted AS but include their own attack site URI as the callback
for the redirect finish method. The attacker would then send the for the redirect finish method. The attacker would then send the
interaction start URI to the victim and get them to click on it. interaction start URI to the victim and get them to click on it.
Since the URI is at the known AS, the victim is inclined to do so. Since the URI is at the known AS, the victim is inclined to do so.
The victim will then be prompted to approve the attacker's The victim will then be prompted to approve the attacker's
application, and in most circumstances the victim will then be application, and in most circumstances, the victim will then be
redirected to the attacker's site whether or not the user approved redirected to the attacker's site whether or not the user approved
the request. The AS could mitigate this partially by using a the request. The AS could mitigate this partially by using a
blocklist and allowlist of interaction finish URIs during the client blocklist and allowlist of interaction finish URIs during the client
instance's initial request, but this approach can be especially instance's initial request, but this approach can be especially
difficult if the URI has any dynamic portion chosen by the client difficult if the URI has any dynamic portion chosen by the client
software. The AS can couple these checks with policies associated software. The AS can couple these checks with policies associated
with the client instance that has been authenticated in the request. with the client instance that has been authenticated in the request.
If the AS has any doubt about the interaction finish URI, the AS can If the AS has any doubt about the interaction finish URI, the AS can
provide an interstitial warning to the end user before processing the provide an interstitial warning to the end user before processing the
redirect. redirect.
Ultimately, all protocols that use redirect-based communication Ultimately, all protocols that use redirect-based communication
through the user's browser are susceptible to having an attacker try through the user's browser are susceptible to having an attacker try
to co-opt one or more of those URIs in order to harm the user. It is to co-opt one or more of those URIs in order to harm the user. It is
the responsibility of the AS and the client software to provide the responsibility of the AS and the client software to provide
appropriate warnings, education, and mitigation to protect end users. appropriate warnings, education, and mitigation to protect end users.
13.30. Processing Assertions 11.30. Processing Assertions
Identity assertions can be used in GNAP to convey subject Identity assertions can be used in GNAP to convey subject
information, both from the AS to the client instance in a response information, both from the AS to the client instance in a response
(Section 3.4) and from the client instance to the AS in a request (Section 3.4) and from the client instance to the AS in a request
(Section 2.2). In both of these circumstances, when an assertion is (Section 2.2). In both of these circumstances, when an assertion is
passed in GNAP, the receiver of the assertion needs to parse and passed in GNAP, the receiver of the assertion needs to parse and
process the assertion. As assertions are complex artifacts with process the assertion. As assertions are complex artifacts with
their own syntax and security, special care needs to be taken to their own syntax and security, special care needs to be taken to
prevent the assertion values from being used as an attack vector. prevent the assertion values from being used as an attack vector.
All assertion processing needs to account for the security aspects of All assertion processing needs to account for the security aspects of
the assertion format in use. In particular, the processor needs to the assertion format in use. In particular, the processor needs to
parse the assertion from a JSON string object, and apply the parse the assertion from a JSON string object and apply the
appropriate cryptographic processes to ensure the integrity of the appropriate cryptographic processes to ensure the integrity of the
assertion. assertion.
For example, when SAML 2 assertions are used, the receiver has to For example, when SAML 2.0 assertions are used, the receiver has to
parse an XML document. There are many well-known security parse an XML document. There are many well-known security
vulnerabilities in XML parsers, and the XML standard itself can be vulnerabilities in XML parsers, and the XML standard itself can be
attacked through the use of processing instructions and entity attacked through the use of processing instructions and entity
expansions to cause problems with the processor. Therefore, any expansions to cause problems with the processor. Therefore, any
system capable of processing SAML 2 assertions also needs to have a system capable of processing SAML 2.0 assertions also needs to have a
secure and correct XML parser. In addition to this, the SAML 2 secure and correct XML parser. In addition to this, the SAML 2.0
specification uses XML Signatures, which have their own specification uses XML Signatures, which have their own
implementation problems that need to be accounted for. Similar implementation problems that need to be accounted for. Similar
requirements exist for OpenID Connect's ID token, which is based on requirements exist for OpenID Connect ID Token, which is based on the
the JSON Web Token (JWT) format and the related JSON Object Signing JWT format and the related JOSE cryptography suite.
And Encryption (JOSE) cryptography suite.
13.31. Stolen Token Replay 11.31. Stolen Token Replay
If a client instance can request tokens at multiple AS's, and the If a client instance can request tokens at multiple ASes and the
client instance uses the same keys to make its requests across those client instance uses the same keys to make its requests across those
different AS's, then it is possible for an attacker to replay a different ASes, then it is possible for an attacker to replay a
stolen token issued by an honest AS from a compromised AS, thereby stolen token issued by an honest AS from a compromised AS, thereby
binding the stolen token to the client instance's key in a different binding the stolen token to the client instance's key in a different
context. The attacker can manipulate the client instance into using context. The attacker can manipulate the client instance into using
the stolen token at an RS, particularly at an RS that is expecting a the stolen token at an RS, particularly at an RS that is expecting a
token from the honest AS. Since the honest AS issued the token and token from the honest AS. Since the honest AS issued the token and
the client instance presents the token with its expected bound key, the client instance presents the token with its expected bound key,
the attack succeeds. the attack succeeds.
This attack has several preconditions. In this attack, the attacker This attack has several preconditions. In this attack, the attacker
does not need access to the client instance's key and cannot use the does not need access to the client instance's key and cannot use the
stolen token directly at the RS, but the attacker is able to get the stolen token directly at the RS, but the attacker is able to get the
access token value in some fashion. The client instance also needs access token value in some fashion. The client instance also needs
to be configured to talk to multiple AS's, including the attacker's to be configured to talk to multiple ASes, including the attacker's
controlled AS. Finally, the client instance needs to be able to be controlled AS. Finally, the client instance needs to be able to be
manipulated by the attacker to call the RS while using a token issued manipulated by the attacker to call the RS while using a token issued
from the stolen AS. The RS does not need to be compromised or made from the stolen AS. The RS does not need to be compromised or made
to trust the attacker's AS. to trust the attacker's AS.
To protect against this attack, the client instance can use a To protect against this attack, the client instance can use a
different key for each AS that it talks to. Since the replayed token different key for each AS that it talks to. Since the replayed token
will be bound to the key used at the honest AS, the uncompromised RS will be bound to the key used at the honest AS, the uncompromised RS
will reject the call since the client instance will be using the key will reject the call since the client instance will be using the key
used at the attacker's AS instead with the same token. When the MTLS used at the attacker's AS instead with the same token. When the MTLS
key proofing method is used, a client instance can use self-signed key proofing method is used, a client instance can use self-signed
certificates to use a different key for each AS that it talks to, as certificates to use a different key for each AS that it talks to, as
discussed in Section 13.4. discussed in Section 11.4.
Additionally, the client instance can keep a strong association Additionally, the client instance can keep a strong association
between the RS and a specific AS that it trusts to issue tokens for between the RS and a specific AS that it trusts to issue tokens for
that RS. This strong binding also helps against some forms of AS that RS. This strong binding also helps against some forms of AS
mix-up attacks (Section 13.12). Managing this binding is outside the mix-up attacks (Section 11.12). Managing this binding is outside the
scope of GNAP core, but it can be managed either as a configuration scope of this specification, but it can be managed either as a
element for the client instance or dynamically through discovering configuration element for the client instance or dynamically through
the AS from the RS (Section 9.1). discovering the AS from the RS (Section 9.1).
The details of this attack are available in [HELMSCHMIDT2022] with The details of this attack, with additional discussion and
additional discussion and considerations. considerations, are available in Section 3.2 of [HELMSCHMIDT2022].
13.32. Self-contained Stateless Access Tokens 11.32. Self-Contained Stateless Access Tokens
The contents and format of the access token are at the discretion of The contents and format of the access token are at the discretion of
the AS, and are opaque to the client instance within GNAP. As the AS and are opaque to the client instance within GNAP. As
discussed in the companion document, discussed in [GNAP-RS], the AS and RS can make use of stateless
[I-D.ietf-gnap-resource-servers], the AS and RS can make use of access tokens with an internal structure and format. These access
stateless access tokens with an internal structure and format. These tokens allow an RS to validate the token without having to make any
access tokens allow an RS to validate the token without having to external calls at runtime, allowing for benefits in some deployments,
make any external calls at runtime, allowing for benefits in some the discussion of which is outside the scope of this specification.
deployments, the discussion of which are outside the scope of this
specification.
However, the use of such self-contained access tokens has an effect However, the use of such self-contained access tokens has an effect
on the ability of the AS to provide certain functionality defined on the ability of the AS to provide certain functionality defined
within this specification. Specifically, since the access token is within this specification. Specifically, since the access token is
self-contained, it is difficult or impossible for an AS to signal to self-contained, it is difficult or impossible for an AS to signal to
all RS's within an ecosystem when a specific access token has been all RSs within an ecosystem when a specific access token has been
revoked. Therefore, an AS in such an ecosystem should probably not revoked. Therefore, an AS in such an ecosystem should probably not
offer token revocation functionality to client instances, since the offer token revocation functionality to client instances, since the
client instance's calls to such an endpoint is effectively client instance's calls to such an endpoint are effectively
meaningless. However, a client instance calling the token revocation meaningless. However, a client instance calling the token revocation
function will also throw out its copy of the token, so such a placebo function will also throw out its copy of the token, so such a placebo
endpoint might not be completely meaningless. Token rotation endpoint might not be completely meaningless. Token rotation is
similarly difficult because the AS has to revoke the old access token similarly difficult because the AS has to revoke the old access token
after a rotation call has been made. If the access tokens are after a rotation call has been made. If the access tokens are
completely self-contained and non-revocable, this means that there completely self-contained and non-revocable, this means that there
will be a period of time during which both the old and new access will be a period of time during which both the old and new access
tokens are valid and usable, which is an increased security risk for tokens are valid and usable, which is an increased security risk for
the environment. the environment.
These problems can be mitigated by keeping the validity time windows These problems can be mitigated by keeping the validity time windows
of self-contained access tokens reasonably short, limiting the time of self-contained access tokens reasonably short, limiting the time
after a revocation event that a revoked token could be used. after a revocation event that a revoked token could be used.
Additionally, the AS could proactively signal to RS's under its Additionally, the AS could proactively signal to RSs under its
control identifiers for revoked tokens that have yet to expire. This control identifiers for revoked tokens that have yet to expire. This
type of information push would be expected to be relatively small and type of information push would be expected to be relatively small and
infrequent, and its implementation is outside the scope of this infrequent, and its implementation is outside the scope of this
specification. specification.
13.33. Network Problems and Token and Grant Management 11.33. Network Problems and Token and Grant Management
If a client instance makes a call to rotate an access token but the If a client instance makes a call to rotate an access token but the
network connection is dropped before the client instance receives the network connection is dropped before the client instance receives the
response with the new access token, the system as a whole can end up response with the new access token, the system as a whole can end up
in an inconsistent state, where the AS has already rotated the old in an inconsistent state, where the AS has already rotated the old
access token and invalidated it, but the client instance only has access token and invalidated it, but the client instance only has
access to the invalidated access token and not the newly rotated access to the invalidated access token and not the newly rotated
token value. If the client instance retries the rotation request, it token value. If the client instance retries the rotation request, it
would fail because the client is no longer presenting a valid and would fail because the client is no longer presenting a valid and
current access token. A similar situation can occur during grant current access token. A similar situation can occur during grant
continuation, where the same client instance calls to continue or continuation, where the same client instance calls to continue or
update a grant request without successfully receiving the results of update a grant request without successfully receiving the results of
the update. the update.
To combat this, both grant Management (Section 5) and token To combat this, both grant management (Section 5) and token
management (Section 6) can be designed to be idempotent, where management (Section 6) can be designed to be idempotent, where
subsequent calls to the same function with the same credentials are subsequent calls to the same function with the same credentials are
meant to produce the same results. For example, multiple calls to meant to produce the same results. For example, multiple calls to
rotate the same access token need to result in the same rotated token rotate the same access token need to result in the same rotated token
value, within a reasonable time window. value, within a reasonable time window.
In practice, an AS can hold on to an old token value for such limited In practice, an AS can hold onto an old token value for such limited
purposes. For example, to support rotating access tokens over purposes. For example, to support rotating access tokens over
unreliable networks, the AS receives the initial request to rotate an unreliable networks, the AS receives the initial request to rotate an
access token and creates a new token value and returns it. The AS access token and creates a new token value and returns it. The AS
also marks the old token value as having been used to create the also marks the old token value as having been used to create the
newly-rotated token value. If the AS sees the old token value within newly rotated token value. If the AS sees the old token value within
a small enough time window, such as a few seconds since the first a small enough time window, such as a few seconds since the first
rotation attempt, the AS can return the same rotated access token rotation attempt, the AS can return the same rotated access token
value. Furthermore, once the system has seen the newly-rotated token value. Furthermore, once the system has seen the newly rotated token
in use, the original token can be discarded because the client in use, the original token can be discarded because the client
instance has proved that it did receive the token. The result of instance has proved that it did receive the token. The result of
this is a system that is eventually self-consistent without placing this is a system that is eventually self-consistent without placing
an undue complexity burden on the client instance to manage an undue complexity burden on the client instance to manage
problematic networks. problematic networks.
13.34. Server-side Request Forgery (SSRF) 11.34. Server-Side Request Forgery (SSRF)
There are several places within GNAP where a URI can be given to a There are several places within GNAP where a URI can be given to a
party causing it to fetch that URI during normal operation of the party, causing it to fetch that URI during normal operation of the
protocol. If an attacker is able to control the value of one of protocol. If an attacker is able to control the value of one of
these URIs within the protocol, the attacker could cause the target these URIs within the protocol, the attacker could cause the target
system to execute a request on a URI that is within reach of the system to execute a request on a URI that is within reach of the
target system but normally unavailable to the attacker. For example, target system but normally unavailable to the attacker. Examples
an attacker sending a URL of http://localhost/admin to cause the include an attacker sending a URL of http://localhost/admin to cause
server to access an internal function on itself, or the server to access an internal function on itself or
https://192.168.0.14/ to call a service behind a firewall. Even if https://192.168.0.14/ to call a service behind a firewall. Even if
the attacker does not gain access to the results of the call, the the attacker does not gain access to the results of the call, the
side effects of such requests coming from a trusted host can be side effects of such requests coming from a trusted host can be
problematic to the security and sanctity of such otherwise unexposed problematic to the security and sanctity of such otherwise unexposed
endpoints. This can be particularly problematic if such a URI is endpoints. This can be particularly problematic if such a URI is
used to call non-HTTP endpoints, such as remote code execution used to call non-HTTP endpoints, such as remote code execution
services local to the AS. services local to the AS.
In GNAP, the most vulnerable place in the core protocol is the The most vulnerable place in this specification is the push-based
push-based post-interaction finish method (Section 4.2.2), as the post-interaction finish method (Section 4.2.2), as the client
client instance is less trusted than the AS and can use this method instance is less trusted than the AS and can use this method to make
to make the AS call an arbitrary URI. While it is not required by the AS call an arbitrary URI. While it is not required by the
the protocol, the AS can fetch other client-instance provided URIs protocol, the AS can fetch other URIs provided by the client
such as the logo image or home page, for verification or privacy- instance, such as the logo image or home page, for verification or
preserving purposes before displaying them to the resource owner as privacy-preserving purposes before displaying them to the RO as part
part of a consent screen. Even if the AS does not fetch these URIs, of a consent screen. Even if the AS does not fetch these URIs, their
their use in GNAP's normal operation could cause an attack against use in GNAP's normal operation could cause an attack against the end
the end user's browser as it fetches these same attack URIs. user's browser as it fetches these same attack URIs. Furthermore,
Furthermore, extensions to GNAP that allow or require URI fetch could extensions to GNAP that allow or require URI fetch could also be
also be similarly susceptible, such as a system for having the AS similarly susceptible, such as a system for having the AS fetch a
fetch a client instance's keys from a presented URI instead of the client instance's keys from a presented URI instead of the client
client instance presenting the key by value. Such extensions are instance presenting the key by value. Such extensions are outside
outside the scope of this specification, but any system deploying the scope of this specification, but any system deploying such an
such an extension would need to be aware of this issue. extension would need to be aware of this issue.
To help mitigate this problem, similar approaches to protecting To help mitigate this problem, similar approaches that protect
parties against malicious redirects (Section 13.29) can be used. For parties against malicious redirects (Section 11.29) can be used. For
example, all URIs that can result in a direct request being made by a example, all URIs that can result in a direct request being made by a
party in the protocol can be filtered through an allowlist or party in the protocol can be filtered through an allowlist or
blocklist. For example, an AS that supports the push based blocklist. For example, an AS that supports the push-based
interaction finish can compare the callback URI in the interaction interaction finish method can compare the callback URI in the
request to a known URI for a pre-registered client instance, or it interaction request to a known URI for a pre-registered client
can ensure that the URI is not on a blocklist of sensitive URLs such instance, or it can ensure that the URI is not on a blocklist of
as internal network addresses. However, note that because these sensitive URLs such as internal network addresses. However, note
types of calls happen outside of the view of human interaction, it is that because these types of calls happen outside of the view of human
not usually feasible to provide notification and warning to someone interaction, it is not usually feasible to provide notification and
before the request needs to be executed, as is the case with warning to someone before the request needs to be executed, as is the
redirection URLs. As such, SSRF is somewhat more difficult to manage case with redirection URLs. As such, SSRF is somewhat more difficult
at runtime, and systems should generally refuse to fetch a URI if to manage at runtime, and systems should generally refuse to fetch a
unsure. URI if unsure.
13.35. Multiple Key Formats 11.35. Multiple Key Formats
All keys presented by value are allowed to be in only a single All keys presented by value are only allowed to be in a single
format. While it would seem beneficial to allow keys to be sent in format. While it would seem beneficial to allow keys to be sent in
multiple formats, in case the receiver doesn't understand one or more multiple formats in case the receiver doesn't understand one or more
of the formats used, there would be security issues with such a of the formats used, there are security issues with such a feature.
feature. If multiple keys formats were allowed, receivers of these If multiple keys formats are allowed, receivers of these key
key definitions would need to be able to make sure that it's the same definitions would need to be able to make sure that it's the same key
key represented in each field and not simply use one of the key represented in each field and not simply use one of the key formats
formats without checking for equivalence. If equivalence were not without checking for equivalence. If equivalence is not carefully
carefully checked, it is possible for an attacker to insert their own checked, it is possible for an attacker to insert their own key into
key into one of the formats without needing to have control over the one of the formats without needing to have control over the other
other formats. This could potentially lead to a situation where one formats. This could potentially lead to a situation where one key is
key is used by part of the system (such as identifying the client used by part of the system (such as identifying the client instance)
instance) and a different key in a different format in the same and a different key in a different format in the same message is used
message is used for other things (such as calculating signature for other things (such as calculating signature validity). However,
validity). However, in such cases, it is impossible for the receiver in such cases, it is impossible for the receiver to ensure that all
to ensure that all formats contain the same key information since it formats contain the same key information since it is assumed that the
is assumed that the receiver cannot understand all of the formats. receiver cannot understand all of the formats.
To combat this, all keys presented by value have to be in exactly one To combat this, all keys presented by value have to be in exactly one
supported format known by the receiver as discussed in Section 7.1. supported format known by the receiver as discussed in Section 7.1.
In most cases, a client instance is going to be configured with its In most cases, a client instance is going to be configured with its
keys in a single format, and it will simply present that format as-is keys in a single format, and it will simply present that format as is
to the AS in its request. A client instance capable of multiple to the AS in its request. A client instance capable of multiple
formats can use AS discovery (Section 9) to determine which formats formats can use AS discovery (Section 9) to determine which formats
are supported, if desired. An AS should be generous in supporting are supported, if desired. An AS should be generous in supporting
many different key formats to allow different types of client many different key formats to allow different types of client
software and client instance deployments. An AS implementation software and client instance deployments. An AS implementation
should try to support multiple formats to allow a variety of client should try to support multiple formats to allow a variety of client
software to connect. software to connect.
13.36. Asynchronous Interactions 11.36. Asynchronous Interactions
GNAP allows the RO to be contacted by the AS asynchronously, outside GNAP allows the RO to be contacted by the AS asynchronously, outside
the regular flow of the protocol. This allows for some advanced use the regular flow of the protocol. This allows for some advanced use
cases, such as cross-user authentication or information release, but cases, such as cross-user authentication or information release, but
such advanced use cases have some distinct issues that implementors such advanced use cases have some distinct issues that implementors
need to be fully aware of before using these features. need to be fully aware of before using these features.
First, in many applications, the return of a subject information to First, in many applications, the return of subject information to the
the client instance could indicate to the client instance that the client instance could indicate to the client instance that the end
end-user is the party represented by that information, functionally user is the party represented by that information, functionally
allowing the end-user to authenticate to the client application. allowing the end user to authenticate to the client application.
While the details of a fully functional authentication protocol are While the details of a fully functional authentication protocol are
outside the scope of GNAP, it is a common exercise for a client outside the scope of GNAP, it is a common exercise for a client
instance to be requesting information about the end user. This is instance to request information about the end user. This is
facilitated by the several interaction methods (Section 4.1) defined facilitated by several interaction methods (Section 4.1) defined in
in GNAP that allow the end user to begin interaction directly with GNAP that allow the end user to begin interaction directly with the
the AS. However, when the subject of the information is AS. However, when the subject of the information is intentionally
intentionally not the end-user, the client application will need some not the end user, the client application will need some way to
way to differentiate between requests for authentication of the end differentiate between requests for authentication of the end user and
user and requests for information about a different user. Confusing requests for information about a different user. Confusing these
these states could lead to an attacker having their account states could lead to an attacker having their account associated with
associated with a privileged user. Client instances can mitigate a privileged user. Client instances can mitigate this by having
this by having distinct code paths for primary end user distinct code paths for primary end-user authentication and for
authentication and requesting subject information about secondary requesting subject information about secondary users, such as in a
users, such as in a call center. In such use cases, the client call center. In such use cases, the client software used by the RO
software used by the resource owner (the caller) and the end-user (the caller) and the end user (the agent) are generally distinct,
(the agent) are generally distinct, allowing the AS to differentiate allowing the AS to differentiate between the agent's corporate device
between the agent's corporate device making the request and the making the request and the caller's personal device approving the
caller's personal device approving the request. request.
Second, RO's interacting asynchronously do not usually have the same Second, ROs that interact asynchronously do not usually have the same
context as an end user in an application attempting to perform the context as an end user in an application attempting to perform the
task needing authorization. As such, the asynchronous requests for task needing authorization. As such, the asynchronous requests for
authorization coming to the RO from the AS might have very little to authorization coming to the RO from the AS might have very little to
do with what the RO is doing at the time. This situation can do with what the RO is doing at the time. This situation can
consequently lead to authorization fatigue on the part of the RO, consequently lead to authorization fatigue on the part of the RO,
where any incoming authorization request is quickly approved and where any incoming authorization request is quickly approved and
dispatched without the RO making a proper verification of the dispatched without the RO making a proper verification of the
request. An attacker can exploit this fatigue and get the RO to request. An attacker can exploit this fatigue and get the RO to
authorize the attacker's system for access. To mitigate this, AS authorize the attacker's system for access. To mitigate this, AS
systems deploying asynchronous authorization should only prompt the systems deploying asynchronous authorization should only prompt the
RO when the RO is expecting such a request, and significant user RO when the RO is expecting such a request, and significant user
experience engineering efforts need to be employed to ensure the RO experience engineering efforts need to be employed to ensure that the
can clearly make the appropriate security decision. Furthermore, RO can clearly make the appropriate security decision. Furthermore,
audit capability, and the ability to undo access decisions that may audit capability and the ability to undo access decisions that may be
be ongoing, is particularly important in the asynchronous case. ongoing are particularly important in the asynchronous case.
13.37. Compromised RS 11.37. Compromised RS
An attacker may aim to gain access to confidential or sensitive An attacker may aim to gain access to confidential or sensitive
resources. The measures for hardening and monitoring resource server resources. The measures for hardening and monitoring RS systems
systems (beyond protection with access tokens) is out of the scope of (beyond protection with access tokens) are out of the scope of this
this document, but the use of GNAP to protect a system does not document, but the use of GNAP to protect a system does not absolve
absolve the resource server of following best practices. GNAP the RS of following best practices. GNAP generally considers that a
generally considers a breach can occur, and therefore advises to breach can occur and therefore advises to prefer key-bound tokens
prefer key-bound tokens whenever possible, which at least limits the whenever possible, which at least limits the impact of access token
impact of access token leakage by a compromised or malicious RS. leakage by a compromised or malicious RS.
13.38. AS-Provided Token Keys 11.38. AS-Provided Token Keys
While the most common token issuance pattern is to bind the access While the most common token-issuance pattern is to bind the access
token to the client instance's presented key, it is possible for the token to the client instance's presented key, it is possible for the
AS to provide a binding key along with an access token, as shown by AS to provide a binding key along with an access token, as shown by
the key field of the token response in Section 3.2.1. This practice the key field of the token response in Section 3.2.1. This practice
allows for an AS to generate and manage the keys associated with allows for an AS to generate and manage the keys associated with
tokens independently of the keys known to client instances. tokens independently of the keys known to client instances.
If the key material is returned by value from the AS, then the client If the key material is returned by value from the AS, then the client
instance will simply use this key value when presenting the token. instance will simply use this key value when presenting the token.
This can be exploited by an attacker to issue a compromised token to This can be exploited by an attacker to issue a compromised token to
an unsuspecting client, assuming that the client instance trusts the an unsuspecting client, assuming that the client instance trusts the
attacker's AS to issue tokens for the target RS. In this attack, the attacker's AS to issue tokens for the target RS. In this attack, the
attacker first gets a token bound to a key under the attacker's attacker first gets a token bound to a key under the attacker's
control. This token is likely bound to an authorization or account control. This token is likely bound to an authorization or account
controlled by the attacker. The attacker then re-issues that same controlled by the attacker. The attacker then reissues that same
token to the client instance, this time acting as an AS. The token to the client instance, this time acting as an AS. The
attacker can return their own key to the client instance, tricking attacker can return their own key to the client instance, tricking
the client instance into using the attacker's token. Such an attack the client instance into using the attacker's token. Such an attack
is also possible when the key is returned by reference, if the is also possible when the key is returned by reference, if the
attacker is able to provide a reference meaningful to the client attacker is able to provide a reference meaningful to the client
instance that references a key under the attacker's control. This instance that references a key under the attacker's control. This
substitution attack is similar to some of the main issues found with substitution attack is similar to some of the main issues found with
bearer tokens as discussed in Section 13.9. bearer tokens as discussed in Section 11.9.
Returning a key with an access token should be limited to only Returning a key with an access token should be limited to
circumstances where both the client and AS can be verified to be circumstances where both the client and AS can be verified to be
honest, and further only when the tradeoff of not using a client honest and when the trade-off of not using a client instance's own
instance's own keys is worth the additional risk. keys is worth the additional risk.
14. Privacy Considerations 12. Privacy Considerations
The privacy considerations in this section are modeled after the list The privacy considerations in this section are modeled after the list
of privacy threats in [RFC6973], "Privacy Considerations for Internet of privacy threats in "Privacy Considerations for Internet Protocols"
Protocols", and either explain how these threats are mitigated or [RFC6973] and either explain how these threats are mitigated or
advise how the threats relate to GNAP. advise how the threats relate to GNAP.
14.1. Surveillance 12.1. Surveillance
Surveillance is the observation or monitoring of an individual's Surveillance is the observation or monitoring of an individual's
communications or activities. Surveillance can be conducted by communications or activities. Surveillance can be conducted by
observers or eavesdroppers at any point along the communications observers or eavesdroppers at any point along the communications
path. path.
GNAP assumes the TLS protection used throughout the spec is intact. GNAP assumes the TLS protection used throughout the spec is intact.
Without the protection of TLS, there are many points throughout the Without the protection of TLS, there are many points throughout the
use of GNAP that would lead to possible surveillance. Even with the use of GNAP that could lead to possible surveillance. Even with the
proper use of TLS, surveillance could occur by several parties proper use of TLS, surveillance could occur by several parties
outside of the TLS-protected channels, as discussed in the sections outside of the TLS-protected channels, as discussed in the
below. subsections below.
14.1.1. Surveillance by the Client 12.1.1. Surveillance by the Client
The purpose of GNAP is to authorize clients to be able to access The purpose of GNAP is to authorize clients to be able to access
information on behalf of a user. So while it is expected that the information on behalf of a user. So while it is expected that the
client may be aware of the user's identity as well as data being client may be aware of the user's identity as well as data being
fetched for that user, in some cases the extent of the client may be fetched for that user, in some cases, the extent of the client may be
beyond what the user is aware of. For example, a client may be beyond what the user is aware of. For example, a client may be
implemented as multiple distinct pieces of software, such as a implemented as multiple distinct pieces of software, such as a
logging service or a mobile app that reports usage data to an logging service or a mobile application that reports usage data to an
external backend service. Each of these pieces could gain external backend service. Each of these pieces could gain
information about the user without the user being aware of this information about the user without the user being aware of this
action. action.
When the client software uses a hosted asset for its components, such When the client software uses a hosted asset for its components, such
as its logo image, the fetch of these assets can reveal user actions as its logo image, the fetch of these assets can reveal user actions
to the host. If the AS presents the logo URI to the resource owner to the host. If the AS presents the logo URI to the RO in a browser
in a browser page, the browser will fetch the logo URL from the page, the browser will fetch the logo URL from the authorization
authorization screen. This fetch will tell the host of the logo screen. This fetch will tell the host of the logo image that someone
image that someone is accessing an instance of the client software is accessing an instance of the client software and requesting access
and requesting access for it. This is particularly problematic when for it. This is particularly problematic when the host of the asset
the host of the asset is not the client software itself, such as when is not the client software itself, such as when a content delivery
a content delivery network is used. network is used.
14.1.2. Surveillance by the Authorization Server 12.1.2. Surveillance by the Authorization Server
The role of the authorization server is to manage the authorization The role of the AS is to manage the authorization of client instances
of client instances to protect access to the user's data. In this to protect access to the user's data. In this role, the AS is by
role, the authorization server is by definition aware of each definition aware of each authorization of a client instance by a
authorization of a client instance by a user. When the authorization user. When the AS shares user information with the client instance,
server shares user information with the client instance, it needs to it needs to make sure that it has the permission from that user to do
make sure that it has the permission from that user to do so. so.
Additionally, as part of the authorization grant process, the Additionally, as part of the authorization grant process, the AS may
authorization server may be aware of which resource servers the be aware of which RSs the client intends to use an access token at.
client intends to use an access token at. However, it is possible to However, it is possible to design a system using GNAP in which this
design a system using GNAP in which this knowledge is not made knowledge is not made available to the AS, such as by avoiding the
available to the authorization server, such as by avoiding the use of use of the locations object in the authorization request.
the locations object in the authorization request.
If the authorization server's implementation of access tokens is such If the AS's implementation of access tokens is such that it requires
that it requires a resource server call back to the authorization an RS callback to the AS to validate them, then the AS will be aware
server to validate them, then the authorization server will be aware of which RSs are actively in use and by which users and clients. To
of which resource servers are actively in use and by which users and avoid this possibility, the AS would need to structure access tokens
which clients. To avoid this possibility, the authorization server in such a way that they can be validated by the RS without notifying
would need to structure access tokens in such a way that they can be the AS that the token is being validated.
validated by the resource server without notifying the authorization
server that the token is being validated.
14.2. Stored Data 12.2. Stored Data
Several parties in the GNAP process are expected to persist data at Several parties in the GNAP process are expected to persist data at
least temporarily, if not semi-permanently, for the normal least temporarily, if not semi-permanently, for the normal
functioning of the system. If compromised, this could lead to functioning of the system. If compromised, this could lead to
exposure of sensitive information. This section documents the exposure of sensitive information. This section documents the
potentially sensitive information each party in GNAP is expected to potentially sensitive information each party in GNAP is expected to
store for normal operation. Naturally it is possible that any party store for normal operation. Naturally, it is possible for any party
is storing information for longer than technically necessary of the to store information related to protocol mechanics (such as audit
protocol mechanics (such as audit logs, etc). logs, etc.) for longer than is technically necessary.
The authorization server is expected to store subject identifiers for The AS is expected to store Subject Identifiers for users
users indefinitely, in order to be able to include them in the indefinitely, in order to be able to include them in the responses to
responses to clients. The authorization server is also expected to clients. The AS is also expected to store client key identifiers
store client key identifiers associated with display information associated with display information about the client, such as its
about the client such as its name and logo. name and logo.
The client is expected to store its client instance key indefinitely, The client is expected to store its client instance key indefinitely,
in order to authenticate to the authorization server for the normal in order to authenticate to the AS for the normal functioning of the
functioning of the GNAP flows. Additionally, the client will be GNAP flows. Additionally, the client will be temporarily storing
temporarily storing artifacts issued by the authorization server artifacts issued by the AS during a flow, and these artifacts ought
during a flow, and these artifacts ought to be discarded by the to be discarded by the client when the transaction is complete.
client when the transaction is complete.
The resource server is not required to store any state for its normal The RS is not required to store any state for its normal operation,
operation, as far as its part in implementing GNAP. Depending on the as far as its part in implementing GNAP. Depending on the
implementation of access tokens, the resource server may need to implementation of access tokens, the RS may need to cache public keys
cache public keys from the authorization server in order to validate from the AS in order to validate access tokens.
access tokens.
14.3. Intrusion 12.3. Intrusion
Intrusion refers to the ability of various parties to send Intrusion refers to the ability of various parties to send
unsolicited messages or cause denial of service for unrelated unsolicited messages or cause denial of service for unrelated
parties. parties.
If the resource owner is different from the end user, there is an If the RO is different from the end user, there is an opportunity for
opportunity for the end user to cause unsolicited messages to be sent the end user to cause unsolicited messages to be sent to the RO if
to the resource owner if the system prompts the resource owner for the system prompts the RO for consent when an end user attempts to
consent when an end user attempts to access their data. access their data.
The format and contents of subject identifiers are intentionally not The format and contents of Subject Identifiers are intentionally not
defined by GNAP. If the authorization server uses values for subject defined by GNAP. If the AS uses values for Subject Identifiers that
identifiers that are also identifiers for communication channels, are also identifiers for communication channels (e.g., an email
(e.g. an email address or phone number), this opens up the address or phone number), this opens up the possibility for a client
possibility for a client to learn this information when it was not to learn this information when it was not otherwise authorized to
otherwise authorized to access this kind of data about the user. access this kind of data about the user.
14.4. Correlation 12.4. Correlation
The threat of correlation is the combination of various pieces of The threat of correlation is the combination of various pieces of
information related to an individual in a way that defies their information related to an individual in a way that defies their
expectations of what others know about them. expectations of what others know about them.
14.4.1. Correlation by Clients 12.4.1. Correlation by Clients
The biggest risk of correlation in GNAP is when an authorization The biggest risk of correlation in GNAP is when an AS returns stable,
server returns stable consistent user identifiers to multiple consistent user identifiers to multiple different applications. In
different applications. In this case, applications created by this case, applications created by different parties would be able to
different parties would be able to correlate these user identifiers correlate these user identifiers out of band in order to know which
out of band in order to know which users they have in common. users they have in common.
The most common example of this in practice is tracking for The most common example of this in practice is tracking for
advertising purposes, such that a client shares their list of user advertising purposes, such that a client shares their list of user
IDs with an ad platform that is then able to retarget ads to IDs with an ad platform that is then able to retarget ads to
applications created by other parties. In contrast, a positive applications created by other parties. In contrast, a positive
example of correlation is a corporate acquisition where two example of correlation is a corporate acquisition where two
previously unrelated clients now do need to be able to identify the previously unrelated clients now do need to be able to identify the
same user between the two clients, such as when software systems are same user between the two clients, such as when software systems are
intentionally connected by the end user. intentionally connected by the end user.
Another means of correlation comes from the use of RS-first discovery Another means of correlation comes from the use of RS-first discovery
(Section 9.1). A client instance knowing nothing other than an RS's (Section 9.1). A client instance that knows nothing other than an
URL could make an unauthenticated call to the RS and learn which AS RS's URL could make an unauthenticated call to the RS and learn which
protects the resources there. If the client instance knows something AS protects the resources there. If the client instance knows
about the AS, such as it being a single-user AS or belonging to a something about the AS, such as it being a single-user AS or
specific organization, the client instance could, through belonging to a specific organization, the client instance could,
association, learn things about the resource without ever gaining through association, learn things about the resource without ever
access to the resource itself. gaining access to the resource itself.
14.4.2. Correlation by Resource Servers 12.4.2. Correlation by Resource Servers
Unrelated resource servers also have an opportunity to correlate Unrelated RSs also have an opportunity to correlate users if the AS
users if the authorization server includes stable user identifiers in includes stable user identifiers in access tokens or in access token
access tokens or in access token introspection responses. introspection responses.
In some cases a resource server may not actually need to be able to In some cases, an RS may not actually need to be able to identify
identify users, (such as a resource server providing access to a users (such as an RS providing access to a company cafeteria menu,
company cafeteria menu which only needs to validate whether the user which only needs to validate whether the user is a current employee),
is a current employee), so authorization servers should be thoughtful so ASes should be thoughtful of when user identifiers are actually
of when user identifiers are actually necessary to communicate to necessary to communicate to RSs for the functioning of the system.
resource servers for the functioning of the system.
However, note that the lack of inclusion of a user identifier in an However, note that the lack of inclusion of a user identifier in an
access token may be a risk if there is a concern that two users may access token may be a risk if there is a concern that two users may
voluntarily share access tokens between them in order to access voluntarily share access tokens between them in order to access
protected resources. For example, if a website wants to limit access protected resources. For example, if a website wants to limit access
to only people over 18, and such does not need to know any user to only people over 18, and such does not need to know any user
identifiers, an access token may be issued by an AS contains only the identifiers, an access token may be issued by an AS contains only the
claim "over 18". If the user is aware that this access token doesn't claim "over 18". If the user is aware that this access token doesn't
reference them individually, they may be willing to share the access reference them individually, they may be willing to share the access
token with a user who is under 18 in order to let them get access to token with a user who is under 18 in order to let them get access to
the website. (Note that the binding of an access token to a non- the website. (Note that the binding of an access token to a non-
extractable client instance key also prevents the access token from extractable client instance key also prevents the access token from
being voluntarily shared.) being voluntarily shared.)
14.4.3. Correlation by Authorization Servers 12.4.3. Correlation by Authorization Servers
Clients are expected to be identified by their client instance key. Clients are expected to be identified by their client instance key.
If a particular client instance key is used at more than one If a particular client instance key is used at more than one AS, this
authorization server, this could open up the possibility for multiple could open up the possibility for multiple unrelated ASes to
unrelated authorization servers to correlate client instances. This correlate client instances. This is especially a problem in the
is especially a problem in the common case where a client instance is common case where a client instance is used by a single individual,
used by a single individual, as it would allow the authorization as it would allow the ASes to correlate that individual between them.
servers to correlate that individual between them. If this is a If this is a concern of a client, the client should use distinct keys
concern of a client, the client should use distinct keys with each with each AS.
authorization server.
14.5. Disclosure in Shared References 12.5. Disclosure in Shared References
Throughout many parts of GNAP, the parties pass shared references Throughout many parts of GNAP, the parties pass shared references
between each other, sometimes in place of the values themselves. For between each other, sometimes in place of the values themselves (for
example the interact_ref value used throughout the flow. These example, the interact_ref value used throughout the flow). These
references are intended to be random strings and should not contain references are intended to be random strings and should not contain
any private or sensitive data that would potentially leak information any private or sensitive data that could potentially leak information
between parties. between parties.
15. References 13. References
15.1. Normative References 13.1. Normative References
[BCP195] Best Current Practice 195, [BCP195] Best Current Practice 195,
<https://www.rfc-editor.org/info/bcp195>. <https://www.rfc-editor.org/info/bcp195>.
At the time of writing, this BCP comprises the following: At the time of writing, this BCP comprises the following:
Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS
1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, March 2021, 1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, March 2021,
<https://www.rfc-editor.org/info/rfc8996>. <https://www.rfc-editor.org/info/rfc8996>.
Sheffer, Y., Saint-Andre, P., and T. Fossati, Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer "Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/info/rfc9325>. 2022, <https://www.rfc-editor.org/info/rfc9325>.
[HASH-ALG] IANA, "Named Information Hash Algorithm Registry", n.d., [HASH-ALG] IANA, "Named Information Hash Algorithm Registry",
<https://www.iana.org/assignments/named-information/named- <https://www.iana.org/assignments/named-information/>.
information.xhtml#hash-alg>.
[HTTP] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [HTTP] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110, Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022, DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/rfc/rfc9110>. <https://www.rfc-editor.org/info/rfc9110>.
[OIDC] Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and [OIDC] Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
C. Mortimore, "OpenID Connect Core 1.0 incorporating C. Mortimore, "OpenID Connect Core 1.0 incorporating
errata set 1", November 2014, errata set 2", December 2023,
<https://openid.net/specs/openid-connect-core-1_0.html>. <https://openid.net/specs/openid-connect-core-1_0.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2397] Masinter, L., "The "data" URL scheme", RFC 2397, [RFC2397] Masinter, L., "The "data" URL scheme", RFC 2397,
DOI 10.17487/RFC2397, August 1998, DOI 10.17487/RFC2397, August 1998,
<https://www.rfc-editor.org/rfc/rfc2397>. <https://www.rfc-editor.org/info/rfc2397>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/rfc/rfc3339>. <https://www.rfc-editor.org/info/rfc3339>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/rfc/rfc4648>. <https://www.rfc-editor.org/info/rfc4648>.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying [RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, <https://www.rfc-editor.org/rfc/rfc5646>. September 2009, <https://www.rfc-editor.org/info/rfc5646>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012, RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/rfc/rfc6749>. <https://www.rfc-editor.org/info/rfc6749>.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization [RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750, Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC6750, October 2012, DOI 10.17487/RFC6750, October 2012,
<https://www.rfc-editor.org/rfc/rfc6750>. <https://www.rfc-editor.org/info/rfc6750>.
[RFC7468] Josefsson, S. and S. Leonard, "Textual Encodings of PKIX, [RFC7468] Josefsson, S. and S. Leonard, "Textual Encodings of PKIX,
PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468, PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468,
April 2015, <https://www.rfc-editor.org/rfc/rfc7468>. April 2015, <https://www.rfc-editor.org/info/rfc7468>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/rfc/rfc7515>. 2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517, [RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015, DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/rfc/rfc7517>. <https://www.rfc-editor.org/info/rfc7517>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259, Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017, DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/rfc/rfc8259>. <https://www.rfc-editor.org/info/rfc8259>.
[RFC8705] Campbell, B., Bradley, J., Sakimura, N., and T. [RFC8705] Campbell, B., Bradley, J., Sakimura, N., and T.
Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication
and Certificate-Bound Access Tokens", RFC 8705, and Certificate-Bound Access Tokens", RFC 8705,
DOI 10.17487/RFC8705, February 2020, DOI 10.17487/RFC8705, February 2020,
<https://www.rfc-editor.org/rfc/rfc8705>. <https://www.rfc-editor.org/info/rfc8705>.
[RFC9111] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [RFC9111] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Caching", STD 98, RFC 9111, Ed., "HTTP Caching", STD 98, RFC 9111,
DOI 10.17487/RFC9111, June 2022, DOI 10.17487/RFC9111, June 2022,
<https://www.rfc-editor.org/rfc/rfc9111>. <https://www.rfc-editor.org/info/rfc9111>.
[RFC9421] Backman, A., Ed., Richer, J., Ed., and M. Sporny, "HTTP [RFC9421] Backman, A., Ed., Richer, J., Ed., and M. Sporny, "HTTP
Message Signatures", RFC 9421, DOI 10.17487/RFC9421, Message Signatures", RFC 9421, DOI 10.17487/RFC9421,
February 2024, <https://www.rfc-editor.org/rfc/rfc9421>. February 2024, <https://www.rfc-editor.org/info/rfc9421>.
[RFC9493] Backman, A., Ed., Scurtescu, M., and P. Jain, "Subject [RFC9493] Backman, A., Ed., Scurtescu, M., and P. Jain, "Subject
Identifiers for Security Event Tokens", RFC 9493, Identifiers for Security Event Tokens", RFC 9493,
DOI 10.17487/RFC9493, December 2023, DOI 10.17487/RFC9493, December 2023,
<https://www.rfc-editor.org/rfc/rfc9493>. <https://www.rfc-editor.org/info/rfc9493>.
[RFC9530] Polli, R. and L. Pardue, "Digest Fields", RFC 9530, [RFC9530] Polli, R. and L. Pardue, "Digest Fields", RFC 9530,
DOI 10.17487/RFC9530, February 2024, DOI 10.17487/RFC9530, February 2024,
<https://www.rfc-editor.org/rfc/rfc9530>. <https://www.rfc-editor.org/info/rfc9530>.
[SAML2] Cantor, S., Kemp, J., Philpott, R., and E. Maler, [SAML2] Cantor, S., Ed., Kemp, J., Ed., Philpott, R., Ed., and E.
"Assertions and Protocol for the OASIS Security Assertion Maler, Ed., "Assertions and Protocol for the OASIS
Markup Language (SAML) V2.0", March 2005, Security Assertion Markup Language (SAML) V2.0", OASIS
<https://docs.oasis-open.org/security/saml/v2.0/saml-core- Standard, March 2005, <https://docs.oasis-
2.0-os.pdf>. open.org/security/saml/v2.0/saml-core-2.0-os.pdf>.
15.2. Informative References 13.2. Informative References
[Auth-Schemes]
IANA, "HTTP Authentication Schemes",
<https://www.iana.org/assignments/http-authschemes>.
[AXELAND2021] [AXELAND2021]
Axeland, Å. and O. Oueidat, "Security Analysis of Attack Axeland, Å. and O. Oueidat, "Security Analysis of Attack
Surfaces on the Grant Negotiation and Authorization Surfaces on the Grant Negotiation and Authorization
Protocol", 2021, Protocol", Master's thesis, Department of Computer Science
<https://odr.chalmers.se/handle/20.500.12380/304105>. and Engineering, Chalmers University of Technology and
University of Gothenburg, 2021,
<https://hdl.handle.net/20.500.12380/304105>.
[HELMSCHMIDT2022] [GNAP-REG] IANA, "Grant Negotiation and Authorization Protocol
Helmschmidt, F., "Security Analysis of the Grant (GNAP)", <https://www.iana.org/assignments/gnap>.
Negotiation and Authorization Protocol", 2022,
<http://dx.doi.org/10.18419/opus-12203>.
[I-D.ietf-gnap-resource-servers] [GNAP-RS] Richer, J., Ed. and F. Imbault, "Grant Negotiation and
Richer, J. and F. Imbault, "Grant Negotiation and
Authorization Protocol Resource Server Connections", Work Authorization Protocol Resource Server Connections", Work
in Progress, Internet-Draft, draft-ietf-gnap-resource- in Progress, Internet-Draft, draft-ietf-gnap-resource-
servers-05, 19 February 2024, servers-08, 9 August 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-gnap- <https://datatracker.ietf.org/doc/html/draft-ietf-gnap-
resource-servers-05>. resource-servers-08>.
[I-D.ietf-oauth-security-topics] [HELMSCHMIDT2022]
Helmschmidt, F., "Security Analysis of the Grant
Negotiation and Authorization Protocol", Master's thesis,
Institute of Information Security, University of Stuggart,
DOI 10.18419/opus-12203, 2022,
<http://dx.doi.org/10.18419/opus-12203>.
[MediaTypes]
IANA, "Media Types",
<https://www.iana.org/assignments/media-types>.
[OAUTH-SEC-TOPICS]
Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett, Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett,
"OAuth 2.0 Security Best Current Practice", Work in "OAuth 2.0 Security Best Current Practice", Work in
Progress, Internet-Draft, draft-ietf-oauth-security- Progress, Internet-Draft, draft-ietf-oauth-security-
topics-25, 8 February 2024, topics-29, 3 June 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-oauth- <https://datatracker.ietf.org/doc/html/draft-ietf-oauth-
security-topics-25>. security-topics-29>.
[IANA.MediaTypes]
IANA, "Media Types", n.d.,
<https://www.iana.org/assignments/media-types/media-
types.xhtml>.
[promise-theory] [promise-theory]
Burgess, M. and J. Bergstra, "Promise theory", January Bergstra, J. and M. Burgess, "Promise Theory: Principles
2014, <http://markburgess.org/promises.html>. and Applications", Second Edition, XtAxis Press, 2019,
<http://markburgess.org/promises.html>.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046, Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996, DOI 10.17487/RFC2046, November 1996,
<https://www.rfc-editor.org/rfc/rfc2046>. <https://www.rfc-editor.org/info/rfc2046>.
[RFC4107] Bellovin, S. and R. Housley, "Guidelines for Cryptographic [RFC4107] Bellovin, S. and R. Housley, "Guidelines for Cryptographic
Key Management", BCP 107, RFC 4107, DOI 10.17487/RFC4107, Key Management", BCP 107, RFC 4107, DOI 10.17487/RFC4107,
June 2005, <https://www.rfc-editor.org/rfc/rfc4107>. June 2005, <https://www.rfc-editor.org/info/rfc4107>.
[RFC6202] Loreto, S., Saint-Andre, P., Salsano, S., and G. Wilkins, [RFC6202] Loreto, S., Saint-Andre, P., Salsano, S., and G. Wilkins,
"Known Issues and Best Practices for the Use of Long "Known Issues and Best Practices for the Use of Long
Polling and Streaming in Bidirectional HTTP", RFC 6202, Polling and Streaming in Bidirectional HTTP", RFC 6202,
DOI 10.17487/RFC6202, April 2011, DOI 10.17487/RFC6202, April 2011,
<https://www.rfc-editor.org/rfc/rfc6202>. <https://www.rfc-editor.org/info/rfc6202>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13, Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013, RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/rfc/rfc6838>. <https://www.rfc-editor.org/info/rfc6838>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973, Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013, DOI 10.17487/RFC6973, July 2013,
<https://www.rfc-editor.org/rfc/rfc6973>. <https://www.rfc-editor.org/info/rfc6973>.
[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, [RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015, DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/rfc/rfc7518>. <https://www.rfc-editor.org/info/rfc7518>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8264] Saint-Andre, P. and M. Blanchet, "PRECIS Framework: [RFC8264] Saint-Andre, P. and M. Blanchet, "PRECIS Framework:
Preparation, Enforcement, and Comparison of Preparation, Enforcement, and Comparison of
Internationalized Strings in Application Protocols", Internationalized Strings in Application Protocols",
RFC 8264, DOI 10.17487/RFC8264, October 2017, RFC 8264, DOI 10.17487/RFC8264, October 2017,
<https://www.rfc-editor.org/rfc/rfc8264>. <https://www.rfc-editor.org/info/rfc8264>.
[RFC8707] Campbell, B., Bradley, J., and H. Tschofenig, "Resource [RFC8707] Campbell, B., Bradley, J., and H. Tschofenig, "Resource
Indicators for OAuth 2.0", RFC 8707, DOI 10.17487/RFC8707, Indicators for OAuth 2.0", RFC 8707, DOI 10.17487/RFC8707,
February 2020, <https://www.rfc-editor.org/rfc/rfc8707>. February 2020, <https://www.rfc-editor.org/info/rfc8707>.
[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu, [RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
"Handling Long Lines in Content of Internet-Drafts and "Handling Long Lines in Content of Internet-Drafts and
RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020, RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
<https://www.rfc-editor.org/rfc/rfc8792>. <https://www.rfc-editor.org/info/rfc8792>.
[RFC9396] Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0 [RFC9396] Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0
Rich Authorization Requests", RFC 9396, Rich Authorization Requests", RFC 9396,
DOI 10.17487/RFC9396, May 2023, DOI 10.17487/RFC9396, May 2023,
<https://www.rfc-editor.org/rfc/rfc9396>. <https://www.rfc-editor.org/info/rfc9396>.
[RFC9440] Campbell, B. and M. Bishop, "Client-Cert HTTP Header [RFC9440] Campbell, B. and M. Bishop, "Client-Cert HTTP Header
Field", RFC 9440, DOI 10.17487/RFC9440, July 2023, Field", RFC 9440, DOI 10.17487/RFC9440, July 2023,
<https://www.rfc-editor.org/rfc/rfc9440>. <https://www.rfc-editor.org/info/rfc9440>.
[RFC9525] Saint-Andre, P. and R. Salz, "Service Identity in TLS", [RFC9525] Saint-Andre, P. and R. Salz, "Service Identity in TLS",
RFC 9525, DOI 10.17487/RFC9525, November 2023, RFC 9525, DOI 10.17487/RFC9525, November 2023,
<https://www.rfc-editor.org/rfc/rfc9525>. <https://www.rfc-editor.org/info/rfc9525>.
[SP80063C] Grassi, P., Nadeau, E., Richer, J., Squire, S., Fenton, [SP80063C] Grassi, P., Richer, J., Squire, S., Fenton, J., Nadeau,
J., Lefkovitz, N., Danker, J., Choong, Y., Greene, K., and E., Lefkovitz, N., Danker, J., Choong, Y., Greene, K., and
M. Theofanos, "Digital Identity Guidelines: Federation and M. Theofanos, "Digital Identity Guidelines: Federation and
Assertions", June 2017, Assertions", NIST SP 800-63C, DOI 10.6028/NIST.SP.800-63c,
<https://doi.org/10.6028/NIST.SP.800-63c>. June 2017,
<https://nvlpubs.nist.gov/nistpubs/SpecialPublications/
Appendix A. Document History NIST.SP.800-63c.pdf>.
Note: To be removed by RFC editor before publication.
* 19
- Updates from IESG reviews.
- Updated JOSE types to no longer use subtypes.
- Added media type registrations.
* 18
- Updates from IESG reviews.
* 17
- Updates from IESG reviews.
* 16
- Updates from AD review.
- Added security considerations on token substitution attack.
* 15
- Editorial updates from shepherd review.
- Clarify character set constraints of user codes.
* 14
- Update token rotation to use URI + management token.
- Fix key rotation with HTTP Signatures based on security
analysis.
* -13
- Editoral changes from chair review.
- Clarify that user codes are ungessable.
- Fix user code examples.
- Clarify expectations for extensions to interaction start and
finish methods.
- Fix references.
- Add IANA designated expert instructions.
- Clarify new vs. updated access tokens, and call out no need for
refresh tokens in OAuth 2 comparison section.
- Add instructions on assertion processing.
- Explicitly list user reference lifetime management.
* -12
- Make default hash algorithm SHA256 instead of SHA3-512.
- Remove previous_key from key rotation.
- Defined requirements for key rotation methods.
- Add specificity to context of subject identifier being the AS.
- Editorial updates and protocol clarification.
* -11
- Error as object or string, more complete set of error codes
- Added key rotation in token management.
- Restrict keys to a single format per message.
- Discussed security issues of multiple key formats.
- Make token character set more strict.
- Add note on long-polling in continuation requests.
- Removed "Models" section.
- Rewrote guidance and requirements for extensions.
- Require all URIs to be absolute throughout protocol.
- Make response from RS a "SHOULD" instead of a "MAY".
- Added a way for the client instance to ask for a specific
user's information, separate from the end-user.
- Added security considerations for asynchronous authorization.
- Added security considerations for compromised RS.
- Added interoperability profiles.
- Added implementation status section.
* -10
- Added note on relating access rights sent as strings to rights
sent as objects.
- Expand proofing methods to allow definition by object, with
single string as optimization for common cases.
- Removed "split_token" functionality.
- Collapse "user_code" into a string instead of an object.
- References hash algorithm identifiers from the existing IANA
registry
- Allow interaction responses to time out.
- Added explicit protocol state discussion.
- Added RO policy use case.
* -09
- Added security considerations on redirection status codes.
- Added security considerations on cuckoo token attack.
- Made token management URL required on token rotation.
- Added considerations on token rotation and self-contained
tokens.
- Added security considerations for SSRF.
- Moved normative requirements about end user presence to
security considerations.
- Clarified default wait times for continuation requests
(including polling).
- Clarified URI vs. URL.
- Added "user_code_uri" mode, removed "uri" from "user_code"
mode.
- Consistently formatted all parameter lists.
- Updated examples for HTTP Signatures.
* -08
- Update definition for "Client" to account for the case of no
end user.
- Change definition for "Subject".
- Expanded security and privacy considerations for more
situations.
- Added cross-links from security and privacy considerations.
- Editorial updates.
* -07
- Replace user handle by opaque identifier
- Added trust relationships
- Added privacy considerations section
- Added security considerations.
* -06
- Removed "capabilities" and "existing_grant" protocol fields.
- Removed separate "instance_id" field.
- Split "interaction_methods_supported" into
"interaction_start_modes_supported" and
"interaction_finish_methods_supported".
- Added AS endpoint to hash calculation to fix mix-up attack.
- Added "privileges" field to resource access request object.
- Moved client-facing RS response back from GNAP-RS document.
- Removed oauthpop key binding.
- Removed dpop key binding.
- Added example DID identifier.
- Changed token response booleans to flag structure to match
request.
- Updated signature examples to use HTTP Message Signatures.
* -05
- Changed "interaction_methods" to
"interaction_methods_supported".
- Changed "key_proofs" to "key_proofs_supported".
- Changed "assertions" to "assertions_supported".
- Updated discovery and field names for subject formats.
- Add an appendix to provide protocol rationale, compared to
OAuth2.
- Updated subject information definition.
- Refactored the RS-centric components into a new document.
- Updated cryptographic proof of possession methods to match
current reference syntax.
- Updated proofing language to use "signer" and "verifier"
generically.
- Updated cryptographic proof of possession examples.
- Editorial cleanup and fixes.
- Diagram cleanup and fixes.
* -04
- Updated terminology.
- Refactored key presentation and binding.
- Refactored "interact" request to group start and end modes.
- Changed access token request and response syntax.
- Changed DPoP digest field to 'htd' to match proposed FAPI
profile.
- Include the access token hash in the DPoP message.
- Removed closed issue links.
- Removed function to read state of grant request by client.
- Closed issues related to reading and updating access tokens.
* -03
- Changed "resource client" terminology to separate "client
instance" and "client software".
- Removed OpenID Connect "claims" parameter.
- Dropped "short URI" redirect.
- Access token is mandatory for continuation.
- Removed closed issue links.
- Editorial fixes.
* -02
- Moved all "editor's note" items to GitHub Issues.
- Added JSON types to fields.
- Changed "GNAP Protocol" to "GNAP".
- Editorial fixes.
* -01
- "updated_at" subject info timestamp now in ISO 8601 string
format.
- Editorial fixes.
- Added Aaron and Fabien as document authors.
* -00
- Initial working group draft. [Subj-ID-Formats]
IANA, "Subject Identifier Formats",
<https://www.iana.org/assignments/secevent>.
Appendix B. Compared to OAuth 2.0 Appendix A. Comparison with OAuth 2.0
GNAP's protocol design differs from OAuth 2.0's in several GNAP's protocol design differs from OAuth 2.0's in several
fundamental ways: fundamental ways:
1. *Consent and authorization flexibility:* 1. *Consent and authorization flexibility:*
OAuth 2.0 generally assumes the user has access to a web browser. OAuth 2.0 generally assumes the user has access to a web browser.
The type of interaction available is fixed by the grant type, and The type of interaction available is fixed by the grant type, and
the most common interactive grant types start in the browser. the most common interactive grant types start in the browser.
OAuth 2.0 assumes that the user using the client software is the OAuth 2.0 assumes that the user using the client software is the
same user that will interact with the AS to approve access. same user that will interact with the AS to approve access.
GNAP allows various patterns to manage authorizations and GNAP allows various patterns to manage authorizations and
consents required to fulfill this requested delegation, including consents required to fulfill this requested delegation, including
information sent by the client instance, information supplied by information sent by the client instance, information supplied by
external parties, and information gathered through the external parties, and information gathered through the
interaction process. GNAP allows a client instance to list interaction process. GNAP allows a client instance to list
different ways that it can start and finish an interaction, and different ways that it can start and finish an interaction, and
these can be mixed together as needed for different use cases. these can be mixed together as needed for different use cases.
GNAP interactions can use a browser, but don't have to. Methods GNAP interactions can use a browser, but they don't have to.
can use inter-application messaging protocols, out-of-band data Methods can use inter-application messaging protocols, out-of-
transfer, or anything else. GNAP allows extensions to define new band data transfer, or anything else. GNAP allows extensions to
ways to start and finish an interaction, as new methods and define new ways to start and finish an interaction, as new
platforms are expected to become available over time. GNAP is methods and platforms are expected to become available over time.
designed to allow the end user and the resource owner to be two GNAP is designed to allow the end user and the RO to be two
different people, but still works in the optimized case of them different people, but it still works in the optimized case of
being the same party. them being the same party.
2. *Intent registration and inline negotiation:* 2. *Intent registration and inline negotiation:*
OAuth 2.0 uses different "grant types" that start at different OAuth 2.0 uses different "grant types" that start at different
endpoints for different purposes. Many of these require endpoints for different purposes. Many of these require
discovery of several interrelated parameters. discovery of several interrelated parameters.
GNAP requests all start with the same type of request to the same GNAP requests all start with the same type of request to the same
endpoint at the AS. Next steps are negotiated between the client endpoint at the AS. Next steps are negotiated between the client
instance and AS based on software capabilities, policies instance and AS based on software capabilities, policies
surrounding requested access, and the overall context of the surrounding requested access, and the overall context of the
ongoing request. GNAP defines a continuation API that allows the ongoing request. GNAP defines a continuation API that allows the
client instance and AS to request and send additional information client instance and AS to request and send additional information
from each other over multiple steps. This continuation API uses from each other over multiple steps. This continuation API uses
the same access token protection that other GNAP-protected APIs the same access token protection that other GNAP-protected APIs
use. GNAP allows discovery to optimize the requests but it isn't use. GNAP allows discovery to optimize the requests, but it
required thanks to the negotiation capabilities. isn't required thanks to the negotiation capabilities.
GNAP is able to handle the life-cycle of an authorization GNAP is able to handle the life cycle of an authorization request
request, and therefore simplifies the mental model surrounding and therefore simplifies the mental model surrounding OAuth2.
OAuth2. For instance, there's no need for refresh tokens when For instance, there's no need for refresh tokens when the API
the API enables proper rotation of access tokens. enables proper rotation of access tokens.
3. *Client instances:* 3. *Client instances:*
OAuth 2.0 requires all clients to be registered at the AS and to OAuth 2.0 requires all clients to be registered at the AS and to
use a client_id known to the AS as part of the protocol. This use a client_id known to the AS as part of the protocol. This
client_id is generally assumed to be assigned by a trusted client_id is generally assumed to be assigned by a trusted
authority during a registration process, and OAuth places a lot authority during a registration process, and OAuth places a lot
of trust on the client_id as a result. Dynamic registration of trust on the client_id as a result. Dynamic registration
allows different classes of clients to get a client_id at allows different classes of clients to get a client_id at
runtime, even if they only ever use it for one request. runtime, even if they only ever use it for one request.
skipping to change at page 216, line 49 skipping to change at line 9365
client instance identifier mechanism allows for pre-registered client instance identifier mechanism allows for pre-registered
clients and dynamically registered clients to exist as an clients and dynamically registered clients to exist as an
optimized case without requiring the identifier as part of the optimized case without requiring the identifier as part of the
protocol at all times. protocol at all times.
4. *Expanded delegation:* 4. *Expanded delegation:*
OAuth 2.0 defines the "scope" parameter for controlling access to OAuth 2.0 defines the "scope" parameter for controlling access to
APIs. This parameter has been coopted to mean a number of APIs. This parameter has been coopted to mean a number of
different things in different protocols, including flags for different things in different protocols, including flags for
turning special behavior on and off, including the return of data turning special behavior on and off and the return of data apart
apart from the access token. The "resource" indicator (defined from the access token. The "resource" indicator (defined in
in [RFC8707]) and RAR extensions (as defined in [RFC9396]) expand [RFC8707]) and Rich Authorization Request (RAR) extensions (as
on the "scope" concept in similar but different ways. defined in [RFC9396]) expand on the "scope" concept in similar
but different ways.
GNAP defines a rich structure for requesting access (analogous to GNAP defines a rich structure for requesting access (analogous to
RAR), with string references as an optimization (analogous to RAR), with string references as an optimization (analogous to
scopes). GNAP defines methods for requesting directly-returned scopes). GNAP defines methods for requesting directly returned
user information, separate from API access. This information user information, separate from API access. This information
includes identifiers for the current user and structured includes identifiers for the current user and structured
assertions. The core GNAP protocol makes no assumptions or assertions. GNAP makes no assumptions or demands on the format
demands on the format or contents of the access token, but the RS or contents of the access token, but the RS extension allows a
extension allows a negotiation of token formats between the AS negotiation of token formats between the AS and RS.
and RS.
5. *Cryptography-based security:* 5. *Cryptography-based security:*
OAuth 2.0 uses shared bearer secrets, including the client_secret OAuth 2.0 uses shared bearer secrets, including the client_secret
and access token, and advanced authentication and sender and access token, and advanced authentication and sender
constraint have been built on after the fact in inconsistent constraints have been built on after the fact in inconsistent
ways. ways.
In GNAP, all communication between the client instance and AS is In GNAP, all communication between the client instance and AS is
bound to a key held by the client instance. GNAP uses the same bound to a key held by the client instance. GNAP uses the same
cryptographic mechanisms for both authenticating the client (to cryptographic mechanisms for both authenticating the client (to
the AS) and binding the access token (to the RS and the AS). the AS) and binding the access token (to the RS and the AS).
GNAP allows extensions to define new cryptographic protection GNAP allows extensions to define new cryptographic protection
mechanisms, as new methods are expected to become available over mechanisms, as new methods are expected to become available over
time. GNAP does not have a notion of "public clients" because time. GNAP does not have the notion of "public clients" because
key information can always be sent and used dynamically. key information can always be sent and used dynamically.
6. *Privacy and usable security:* 6. *Privacy and usable security:*
OAuth 2.0's deployment model assumes a strong binding between the OAuth 2.0's deployment model assumes a strong binding between the
AS and the RS. AS and the RS.
GNAP is designed to be interoperable with decentralized identity GNAP is designed to be interoperable with decentralized identity
standards and to provide a human-centric authorization layer. In standards and to provide a human-centric authorization layer. In
addition to the core protocol, GNAP supports various patterns of addition to this specification, GNAP supports various patterns of
communication between RSs and ASs through extensions. GNAP tries communication between RSs and ASes through extensions. GNAP
to limit the odds of a consolidation to just a handful of super- tries to limit the odds of a consolidation to just a handful of
popular AS services. popular AS services.
Appendix C. Example Protocol Flows Appendix B. Example Protocol Flows
The protocol defined in this specification provides a number of The protocol defined in this specification provides a number of
features that can be combined to solve many different kinds of features that can be combined to solve many different kinds of
authentication scenarios. This section seeks to show examples of how authentication scenarios. This section seeks to show examples of how
the protocol would be applied for different situations. the protocol could be applied for different situations.
Some longer fields, particularly cryptographic information, have been Some longer fields, particularly cryptographic information, have been
truncated for display purposes in these examples. truncated for display purposes in these examples.
C.1. Redirect-Based User Interaction B.1. Redirect-Based User Interaction
In this scenario, the user is the RO and has access to a web browser, In this scenario, the user is the RO and has access to a web browser,
and the client instance can take front-channel callbacks on the same and the client instance can take front-channel callbacks on the same
device as the user. This combination is analogous to the OAuth 2.0 device as the user. This combination is analogous to the OAuth 2.0
Authorization Code grant type. Authorization Code grant type.
The client instance initiates the request to the AS. Here the client The client instance initiates the request to the AS. Here, the
instance identifies itself using its public key. client instance identifies itself using its public key.
POST /tx HTTP/1.1 POST /tx HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Content-Digest: sha-256=... Content-Digest: sha-256=...
{ {
"access_token": { "access_token": {
skipping to change at page 219, line 4 skipping to change at line 9466
"key": { "key": {
"proof": "httpsig", "proof": "httpsig",
"jwk": { "jwk": {
"kty": "RSA", "kty": "RSA",
"e": "AQAB", "e": "AQAB",
"kid": "xyz-1", "kid": "xyz-1",
"alg": "RS256", "alg": "RS256",
"n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8..." "n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8..."
} }
} }
}, },
"interact": { "interact": {
"start": ["redirect"], "start": ["redirect"],
"finish": { "finish": {
"method": "redirect", "method": "redirect",
"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
} }
} }
The AS processes the request and determines that the RO needs to The AS processes the request and determines that the RO needs to
interact. The AS returns the following response giving the client interact. The AS returns the following response that gives the
instance the information it needs to connect. The AS has also client instance the information it needs to connect. The AS has also
indicated to the client instance that it can use the given instance indicated to the client instance that it can use the given instance
identifier to identify itself in future requests (Section 2.3.1). identifier to identify itself in future requests (Section 2.3.1).
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"interact": { "interact": {
"redirect": "redirect":
skipping to change at page 221, line 40 skipping to change at line 9585
}] }]
}, },
"continue": { "continue": {
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU" "value": "80UPRY5NM33OMUKMKSKU"
}, },
"uri": "https://server.example.com/continue" "uri": "https://server.example.com/continue"
} }
} }
C.2. Secondary Device Interaction B.2. Secondary Device Interaction
In this scenario, the user does not have access to a web browser on In this scenario, the user does not have access to a web browser on
the device and must use a secondary device to interact with the AS. the device and must use a secondary device to interact with the AS.
The client instance can display a user code or a printable QR code. The client instance can display a user code or a printable QR code.
The client instance is not able to accept callbacks from the AS and The client instance is not able to accept callbacks from the AS and
needs to poll for updates while waiting for the user to authorize the needs to poll for updates while waiting for the user to authorize the
request. request.
The client instance initiates the request to the AS. The client instance initiates the request to the AS.
skipping to change at page 222, line 27 skipping to change at line 9618
}, },
"client": "7C7C4AZ9KHRS6X63AJAO", "client": "7C7C4AZ9KHRS6X63AJAO",
"interact": { "interact": {
"start": ["redirect", "user_code"] "start": ["redirect", "user_code"]
} }
} }
The AS processes this and determines that the RO needs to interact. The AS processes this and determines that the RO needs to interact.
The AS supports both redirect URIs and user codes for interaction, so The AS supports both redirect URIs and user codes for interaction, so
it includes both. Since there is no interaction finish mode, the AS it includes both. Since there is no interaction finish mode, the AS
does not include a nonce, but does include a "wait" parameter on the does not include a nonce but does include a "wait" parameter on the
continuation section because it expects the client instance to poll continuation section because it expects the client instance to poll
for results. for results.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"interact": { "interact": {
"redirect": "https://srv.ex/MXKHQ", "redirect": "https://srv.ex/MXKHQ",
skipping to change at page 223, line 4 skipping to change at line 9641
} }
}, },
"continue": { "continue": {
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU" "value": "80UPRY5NM33OMUKMKSKU"
}, },
"uri": "https://server.example.com/continue/VGJKPTKC50", "uri": "https://server.example.com/continue/VGJKPTKC50",
"wait": 60 "wait": 60
} }
} }
The client instance saves the response and displays the user code The client instance saves the response and displays the user code
visually on its screen along with the static device URI. The client visually on its screen along with the static device URI. The client
instance also displays the short interaction URI as a QR code to be instance also displays the short interaction URI as a QR code to be
scanned. scanned.
If the user scans the code, they are taken to the interaction If the user scans the code, they are taken to the interaction
endpoint and the AS looks up the current pending request based on the endpoint, and the AS looks up the current pending request based on
incoming URI. If the user instead goes to the static page and enters the incoming URI. If the user instead goes to the static page and
the code manually, the AS looks up the current pending request based enters the code manually, the AS looks up the current pending request
on the value of the user code. In both cases, the user logs in, is based on the value of the user code. In both cases, the user logs
identified as the RO for the resource being requested, and approves in, is identified as the RO for the resource being requested, and
the request. Once the request has been approved, the AS displays to approves the request. Once the request has been approved, the AS
the user a message to return to their device. displays to the user a message to return to their device.
Meanwhile, the client instance periodically polls the AS every 60 Meanwhile, the client instance polls the AS every 60 seconds at the
seconds at the continuation URI. The client instance signs the continuation URI. The client instance signs the request using the
request using the same key and method that it did in the first same key and method that it did in the first request.
request.
POST /continue/VGJKPTKC50 HTTP/1.1 POST /continue/VGJKPTKC50 HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Content-Digest: sha-256=... Content-Digest: sha-256=...
The AS retrieves the pending request based on the pending grant The AS retrieves the pending request based on the pending grant
request associated with the continuation access token and determines request associated with the continuation access token and determines
that it has not yet been authorized. The AS indicates to the client that it has not yet been authorized. The AS indicates to the client
instance that no access token has yet been issued but it can continue instance that no access token has yet been issued but it can continue
to call after another 60 second timeout. to call after another 60-second timeout.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "G7YQT4KQQ5TZY9SLSS5E" "value": "G7YQT4KQQ5TZY9SLSS5E"
}, },
skipping to change at page 224, line 4 skipping to change at line 9686
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "G7YQT4KQQ5TZY9SLSS5E" "value": "G7YQT4KQQ5TZY9SLSS5E"
}, },
"uri": "https://server.example.com/continue/ATWHO4Q1WV", "uri": "https://server.example.com/continue/ATWHO4Q1WV",
"wait": 60 "wait": 60
} }
} }
Note that the continuation URI and access token have been rotated Note that the continuation URI and access token have been rotated
since they were used by the client instance to make this call. The since they were used by the client instance to make this call. The
client instance polls the continuation URI after a 60 second timeout client instance polls the continuation URI after a 60-second timeout
using this new information. using this new information.
POST /continue/ATWHO4Q1WV HTTP/1.1 POST /continue/ATWHO4Q1WV HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP G7YQT4KQQ5TZY9SLSS5E Authorization: GNAP G7YQT4KQQ5TZY9SLSS5E
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Content-Digest: sha-256=... Content-Digest: sha-256=...
The AS retrieves the pending request based on the URI and access The AS retrieves the pending request based on the URI and access
skipping to change at page 224, line 37 skipping to change at line 9720
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"manage": "https://server.example.com/token/PRY5NM33O\ "manage": "https://server.example.com/token/PRY5NM33O\
M4TB8N6BW7OZB8CDFONP219RP1L", M4TB8N6BW7OZB8CDFONP219RP1L",
"access": [ "access": [
"dolphin-metadata", "some other thing" "dolphin-metadata", "some other thing"
] ]
} }
} }
C.3. No User Involvement B.3. No User Involvement
In this scenario, the client instance is requesting access on its own In this scenario, the client instance is requesting access on its own
behalf, with no user to interact with. behalf, with no user to interact with.
The client instance creates a request to the AS, identifying itself The client instance creates a request to the AS, identifying itself
with its public key and using MTLS to make the request. with its public key and using MTLS to make the request.
POST /tx HTTP/1.1 POST /tx HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
skipping to change at page 225, line 23 skipping to change at line 9746
], ],
}, },
"client": { "client": {
"key": { "key": {
"proof": "mtls", "proof": "mtls",
"cert#S256": "bwcK0esc3ACC3DB2Y5_lESsXE8o9ltc05O89jdN-dg2" "cert#S256": "bwcK0esc3ACC3DB2Y5_lESsXE8o9ltc05O89jdN-dg2"
} }
} }
} }
The AS processes this and determines that the client instance can ask The AS processes this, determines that the client instance can ask
for the requested resources and issues an access token. for the requested resources, and issues an access token.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"manage": "https://server.example.com/token", "manage": "https://server.example.com/token",
"access": [ "access": [
"backend service", "nightly-routine-3" "backend service", "nightly-routine-3"
] ]
} }
} }
C.4. Asynchronous Authorization B.4. Asynchronous Authorization
In this scenario, the client instance is requesting on behalf of a In this scenario, the client instance is requesting on behalf of a
specific RO, but has no way to interact with the user. The AS can specific RO but has no way to interact with the user. The AS can
asynchronously reach out to the RO for approval in this scenario. asynchronously reach out to the RO for approval in this scenario.
The client instance starts the request at the AS by requesting a set The client instance starts the request at the AS by requesting a set
of resources. The client instance also identifies a particular user. of resources. The client instance also identifies a particular user.
POST /tx HTTP/1.1 POST /tx HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
skipping to change at page 227, line 26 skipping to change at line 9841
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU" "value": "80UPRY5NM33OMUKMKSKU"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 60 "wait": 60
} }
} }
The AS reaches out to the RO and prompts them for consent. In this The AS reaches out to the RO and prompts them for consent. In this
example scenario, the AS has an application that it can push example scenario, the AS has an application that it can push
notifications in to for the specified account. notifications to for the specified account.
Meanwhile, the client instance periodically polls the AS every 60 Meanwhile, the client instance periodically polls the AS every 60
seconds at the continuation URI. seconds at the continuation URI.
POST /continue HTTP/1.1 POST /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
The AS retrieves the pending request based on the continuation access The AS retrieves the pending request based on the continuation access
token and determines that it has not yet been authorized. The AS token and determines that it has not yet been authorized. The AS
indicates to the client instance that no access token has yet been indicates to the client instance that no access token has yet been
issued but it can continue to call after another 60 second timeout. issued but it can continue to call after another 60-second timeout.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "BI9QNW6V9W3XFJK4R02D" "value": "BI9QNW6V9W3XFJK4R02D"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 60 "wait": 60
} }
} }
Note that the continuation access token value has been rotated since Note that the continuation access token value has been rotated since
it was used by the client instance to make this call. The client it was used by the client instance to make this call. The client
instance polls the continuation URI after a 60 second timeout using instance polls the continuation URI after a 60-second timeout using
the new token. the new token.
POST /continue HTTP/1.1 POST /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: GNAP BI9QNW6V9W3XFJK4R02D Authorization: GNAP BI9QNW6V9W3XFJK4R02D
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
The AS retrieves the pending request based on the handle and The AS retrieves the pending request based on the handle, determines
determines that it has been approved and it issues an access token. that it has been approved, and issues an access token.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"manage": "https://server.example.com/token/PRY5NM33O\ "manage": "https://server.example.com/token/PRY5NM33O\
M4TB8N6BW7OZB8CDFONP219RP1L", M4TB8N6BW7OZB8CDFONP219RP1L",
"access": [ "access": [
"dolphin-metadata", "some other thing" "dolphin-metadata", "some other thing"
] ]
} }
} }
C.5. Applying OAuth 2.0 Scopes and Client IDs B.5. Applying OAuth 2.0 Scopes and Client IDs
While GNAP is not designed to be directly compatible with OAuth 2.0 While GNAP is not designed to be directly compatible with OAuth 2.0
[RFC6749], considerations have been made to enable the use of OAuth [RFC6749], considerations have been made to enable the use of OAuth
2.0 concepts and constructs more smoothly within GNAP. 2.0 concepts and constructs more smoothly within GNAP.
In this scenario, the client developer has a client_id and set of In this scenario, the client developer has a client_id and set of
scope values from their OAuth 2.0 system and wants to apply them to scope values from their OAuth 2.0 system and wants to apply them to
the new protocol. Traditionally, the OAuth 2.0 client developer the new protocol. In OAuth 2.0, the client developer would put their
would put their client_id and scope values as parameters into a client_id and scope values as parameters into a redirect request to
redirect request to the authorization endpoint. the authorization endpoint.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
HTTP 302 Found HTTP 302 Found
Location: https://server.example.com/authorize\ Location: https://server.example.com/authorize\
?client_id=7C7C4AZ9KHRS6X63AJAO\ ?client_id=7C7C4AZ9KHRS6X63AJAO\
&scope=read%20write%20dolphin\ &scope=read%20write%20dolphin\
&redirect_uri=https://client.example.net/return\ &redirect_uri=https://client.example.net/return\
&response_type=code\ &response_type=code\
&state=123455 &state=123455
skipping to change at page 230, line 40 skipping to change at line 9963
The client_id can be used to identify the client instance's keys that The client_id can be used to identify the client instance's keys that
it uses for authentication, the scopes represent resources that the it uses for authentication, the scopes represent resources that the
client instance is requesting, and the redirect_uri and state value client instance is requesting, and the redirect_uri and state value
are pre-combined into a finish URI that can be unique per request. are pre-combined into a finish URI that can be unique per request.
The client instance additionally creates a nonce to protect the The client instance additionally creates a nonce to protect the
callback, separate from the state parameter that it has added to its callback, separate from the state parameter that it has added to its
return URI. return URI.
From here, the protocol continues as above. From here, the protocol continues as above.
Appendix D. Interoperability Profiles Appendix C. Interoperability Profiles
The GNAP specification has many different modes, options, and The GNAP specification has many different modes, options, and
mechanisms, allowing it to solve a wide variety of problems in a wide mechanisms, allowing it to solve a wide variety of problems in a wide
variety of deployments. The wide applicability of GNAP makes it variety of deployments. The wide applicability of GNAP makes it
difficult, if not impossible, to define a set of mandatory-to- difficult, if not impossible, to define a set of mandatory-to-
implement features, since one environment's required feature would be implement features, since one environment's required feature would be
impossible to do in another environment. While this is a large impossible to do in another environment. While this is a large
problem in many systems, GNAP's back-and-forth negotiation process problem in many systems, GNAP's back-and-forth negotiation process
allows parties to declare at runtime everything that they support and allows parties to declare at runtime everything that they support and
then have the other party select from that the subset of items that then have the other party select from that the subset of items that
they also support, leading to functional compatibility in many parts they also support, leading to functional compatibility in many parts
of the protocol even in an open world scenario. of the protocol even in an open world scenario.
In addition, GNAP defines a set of interoperability profiles which In addition, GNAP defines a set of interoperability profiles that
gather together core requirements to fix options into common gather together core requirements to fix options into common
configurations that are likely to be useful to large populations of configurations that are likely to be useful to large populations of
similar applications. similar applications.
Conformant AS implementations of these profiles MUST implement at Conformant AS implementations of these profiles MUST implement at
least the features as specified in the profile and MAY implement least the features as specified in the profile and MAY implement
additional features or profiles. Conformant client implementations additional features or profiles. Conformant client implementations
of these profiles MUST implement at least the features as specified, of these profiles MUST implement at least the features as specified,
except where a subset of the features allows the protocol to function except where a subset of the features allows the protocol to function
(such as using polling instead of a push finish method for the (such as using polling instead of a push finish method for the
Secondary Device profile). Secondary Device profile).
D.1. Web-based Redirection C.1. Web-Based Redirection
Implementations conformant to the Web-based Redirection profile of Implementations conformant to the web-based redirection profile of
GNAP MUST implement all of the following features: GNAP MUST implement all of the following features:
* _Interaction Start Methods_: redirect * Interaction Start Methods: redirect
* _Interaction Finish Methods_: redirect * Interaction Finish Methods: redirect
* _Interaction Hash Algorithms_: sha-256 * Interaction Hash Algorithms: sha-256
* _Key Proofing Methods_: httpsig with no additional parameters * Key Proofing Methods: httpsig with no additional parameters
* _Key Formats_: jwks with signature algorithm included in the key's * Key Formats: jwks with signature algorithm included in the key's
alg parameter alg parameter
* _JOSE Signature Algorithm_: PS256 * JOSE Signature Algorithm: PS256
* _Subject Identifier Formats_: opaque * Subject Identifier Formats: opaque
* _Assertion Formats_: id_token * Assertion Formats: id_token
D.2. Secondary Device C.2. Secondary Device
Implementations conformant to the Secondary Device profile of GNAP Implementations conformant to the Secondary Device profile of GNAP
MUST implement all of the following features: MUST implement all of the following features:
* _Interaction Start Methods_: user_code and user_code_uri * Interaction Start Methods: user_code and user_code_uri
* _Interaction Finish Methods_: push * Interaction Finish Methods: push
* _Interaction Hash Algorithms_: sha-256 * Interaction Hash Algorithms: sha-256
* _Key Proofing Methods_: httpsig with no additional parameters * Key Proofing Methods: httpsig with no additional parameters
* _Key Formats_: jwks with signature algorithm included in the key's
* Key Formats: jwks with signature algorithm included in the key's
alg parameter alg parameter
* _JOSE Signature Algorithm_: PS256 * JOSE Signature Algorithm: PS256
* _Subject Identifier Formats_: opaque * Subject Identifier Formats: opaque
* _Assertion Formats_: id_token * Assertion Formats: id_token
Appendix E. Guidance for Extensions Appendix D. Guidance for Extensions
Extensions to this specification have a variety of places to alter Extensions to this specification have a variety of places to alter
the protocol, including many fields and objects that can have the protocol, including many fields and objects that can have
additional values in a registry registry (Section 11) established by additional values in a registry (Section 10) established by this
this specification. For interoperability and to preserve the specification. For interoperability and to preserve the security of
security of the protocol, extensions should register new values with the protocol, extensions should register new values with IANA by
IANA by following the specified mechanism. While it may technically following the specified mechanism. While it may technically be
be possible to extend the protocol by adding elements to JSON objects possible to extend the protocol by adding elements to JSON objects
that are not governed by an IANA registry, a recipient may ignore that are not governed by an IANA registry, a recipient may ignore
such values but is also allowed to reject them. such values but is also allowed to reject them.
Most object fields in GNAP are specified with types, and those types Most object fields in GNAP are specified with types, and those types
can allow different but related behavior. For example, the access can allow different but related behavior. For example, the access
array can include either strings or objects, as discussed in array can include either strings or objects, as discussed in
Section 8. The use of JSON polymorphism (Appendix F) within GNAP Section 8. The use of JSON polymorphism (Appendix E) within GNAP
allows extensions to define new fields by not only choosing a new allows extensions to define new fields by not only choosing a new
name but also by using an existing name with a new type. However, name but also by using an existing name with a new type. However,
the extension's definition of a new type for a field needs to fit the the extension's definition of a new type for a field needs to fit the
same kind of item being extended. For example, a hypothetical same kind of item being extended. For example, a hypothetical
extension could define a string value for the access_token request extension could define a string value for the access_token request
field, with a URL to download a hosted access token request. Such an field, with a URL to download a hosted access token request. Such an
extension would be appropriate as the access_token field still extension would be appropriate as the access_token field still
defines the access tokens being requested. However, if an extension defines the access tokens being requested. However, if an extension
were to define a string value for the access_token request field, were to define a string value for the access_token request field,
with the value instead being something unrelated to the access token with the value instead being something unrelated to the access token
request such as a value or key format, this would not be an request such as a value or key format, this would not be an
appropriate means of extension. (Note that this specific extension appropriate means of extension. (Note that this specific extension
example would create another form of SSRF attack surface as discussed example would create another form of SSRF attack surface as discussed
in Section 13.34.) in Section 11.34.)
For another example, both interaction interaction start modes As another example, both interaction start modes (Section 2.5.1) and
(Section 2.5.1) and key proofing methods (Section 7.3) can be defined key proofing methods (Section 7.3) can be defined as either strings
as either strings or objects. An extension could take a method or objects. An extension could take a method defined as a string,
defined as a string, such as app, and define an object-based version such as app, and define an object-based version with additional
with additional parameters. This extension should still define a parameters. This extension should still define a method to launch an
method to launch an application on the end user's device, just like application on the end user's device, just like app does when
app does when specified as a string. specified as a string.
Additionally, the ability to deal with different types for a field is Additionally, the ability to deal with different types for a field is
not expected to be equal between an AS and client software, with the not expected to be equal between an AS and client software, with the
client software being assumed to be both more varied and more client software being assumed to be both more varied and more
simplified than the AS. Furthermore, the nature of the negotiation simplified than the AS. Furthermore, the nature of the negotiation
process in GNAP allows the AS more chance of recovery from unknown process in GNAP allows the AS more chance of recovery from unknown
situations and parameters. As such, any extensions that change the situations and parameters. As such, any extensions that change the
type of any field returned to a client instance should only do so type of any field returned to a client instance should only do so
when the client instance has indicated specific support for that when the client instance has indicated specific support for that
extension through some kind of request parameter. extension through some kind of request parameter.
Appendix F. JSON Structures and Polymorphism Appendix E. JSON Structures and Polymorphism
GNAP makes use of polymorphism within the JSON [RFC8259] structures GNAP makes use of polymorphism within the JSON [RFC8259] structures
used for the protocol. Each portion of this protocol is defined in used for the protocol. Each portion of this protocol is defined in
terms of the JSON data type that its values can take, whether it's a terms of the JSON data type that its values can take, whether it's a
string, object, array, boolean, or number. For some fields, string, object, array, boolean, or number. For some fields,
different data types offer different descriptive capabilities and are different data types offer different descriptive capabilities and are
used in different situations for the same field. Each data type used in different situations for the same field. Each data type
provides a different syntax to express the same underlying semantic provides a different syntax to express the same underlying semantic
protocol element, which allows for optimization and simplification in protocol element, which allows for optimization and simplification in
many common cases. many common cases.
skipping to change at page 233, line 40 skipping to change at line 10108
be used as the value for any member. In practice, each member has a be used as the value for any member. In practice, each member has a
semantic type that needs to make sense to the parties creating and semantic type that needs to make sense to the parties creating and
consuming the object. Within this protocol, each object member is consuming the object. Within this protocol, each object member is
defined in terms of its semantic content, and this semantic content defined in terms of its semantic content, and this semantic content
might have expressions in different concrete data types for different might have expressions in different concrete data types for different
specific purposes. Since each object member has exactly one value in specific purposes. Since each object member has exactly one value in
JSON, each data type for an object member field is naturally mutually JSON, each data type for an object member field is naturally mutually
exclusive with other data types within a single JSON object. exclusive with other data types within a single JSON object.
For example, a resource request for a single access token is composed For example, a resource request for a single access token is composed
of an object of resource request descriptions while a request for of an object of resource request descriptions, while a request for
multiple access tokens is composed of an array whose member values multiple access tokens is composed of an array whose member values
are all objects. Both of these represent requests for access, but are all objects. Both of these represent requests for access, but
the difference in syntax allows the client instance and AS to the difference in syntax allows the client instance and AS to
differentiate between the two request types in the same request. differentiate between the two request types in the same request.
Another form of polymorphism in JSON comes from the fact that the Another form of polymorphism in JSON comes from the fact that the
values within JSON arrays need not all be of the same JSON data type. values within JSON arrays need not all be of the same JSON data type.
However, within this protocol, each element within the array needs to However, within this protocol, each element within the array needs to
be of the same kind of semantic element for the collection to make be of the same kind of semantic element for the collection to make
sense, even when the data types are different from each other. sense, even when the data types are different from each other.
skipping to change at page 234, line 17 skipping to change at line 10132
requested using a string. In both cases, the resource request is requested using a string. In both cases, the resource request is
being described in a way that the AS needs to interpret, but with being described in a way that the AS needs to interpret, but with
different levels of specificity and complexity for the client different levels of specificity and complexity for the client
instance to deal with. An API designer can provide a set of common instance to deal with. An API designer can provide a set of common
access scopes as simple strings but still allow client software access scopes as simple strings but still allow client software
developers to specify custom access when needed for more complex developers to specify custom access when needed for more complex
APIs. APIs.
Extensions to this specification can use different data types for Extensions to this specification can use different data types for
defined fields, but each extension needs to not only declare what the defined fields, but each extension needs to not only declare what the
data type means, but also provide justification for the data type data type means but also provide justification for the data type
representing the same basic kind of thing it extends. For example, representing the same basic kind of thing it extends. For example,
an extension declaring an "array" representation for a field would an extension declaring an "array" representation for a field would
need to explain how the array represents something akin to the non- need to explain how the array represents something akin to the non-
array element that it is replacing. See additional discussion in array element that it is replacing. See additional discussion in
Appendix E. Appendix D.
Acknowledgements
The authors would like to thank the following individuals for their
reviews, implementations, and contributions: Åke Axeland, Aaron
Parecki, Adam Omar Oueidat, Andrii Deinega, Annabelle Backman, Dick
Hardt, Dmitri Zagidulin, Dmitry Barinov, Florian Helmschmidt, Francis
Pouatcha, George Fletcher, Haardik Haardik, Hamid Massaoud, Jacky
Yuan, Joseph Heenan, Kathleen Moriarty, Leif Johansson, Mike Jones,
Mike Varley, Nat Sakimura, Takahiko Kawasaki, Takahiro Tsuchiya, and
Yaron Sheffer.
The authors would also like to thank the GNAP Working Group design
team (Kathleen Moriarty, Dick Hardt, Mike Jones, and the authors),
who incorporated elements from the XAuth and XYZ proposals to create
the first draft version of this document.
In addition, the authors would like to thank Aaron Parecki and Mike
Jones for insights into how to integrate identity and authentication
systems into the core protocol. Both Justin Richer and Dick Hardt
developed the use cases, diagrams, and insights provided in the XYZ
and XAuth proposals that have been incorporated here. The authors
would like to especially thank Mike Varley and the team at SecureKey
for feedback and development of early versions of the XYZ protocol
that fed into this standards work.
Finally, the authors want to acknowledge the immense contributions of
Aaron Parecki to the content of this document. We thank him for his
insight, input, and hard work, without which GNAP would not have
grown to what it is.
Authors' Addresses Authors' Addresses
Justin Richer (editor) Justin Richer (editor)
Bespoke Engineering Bespoke Engineering
Email: ietf@justin.richer.org Email: ietf@justin.richer.org
URI: https://bspk.io/ URI: https://bspk.io/
Fabien Imbault Fabien Imbault
acert.io acert.io
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