draft-ietf-oauth-v2-1-02.txt   draft-ietf-oauth-v2-1-03.txt 
OAuth Working Group D. Hardt OAuth Working Group D. Hardt
Internet-Draft SignIn.Org Internet-Draft SignIn.Org
Intended status: Standards Track A. Parecki Intended status: Standards Track A. Parecki
Expires: 16 September 2021 Okta Expires: 12 March 2022 Okta
T. Lodderstedt T. Lodderstedt
yes.com yes.com
15 March 2021 8 September 2021
The OAuth 2.1 Authorization Framework The OAuth 2.1 Authorization Framework
draft-ietf-oauth-v2-1-02 draft-ietf-oauth-v2-1-03
Abstract Abstract
The OAuth 2.1 authorization framework enables a third-party The OAuth 2.1 authorization framework enables a third-party
application to obtain limited access to an HTTP service, either on application to obtain limited access to an HTTP service, either on
behalf of a resource owner by orchestrating an approval interaction behalf of a resource owner by orchestrating an approval interaction
between the resource owner and an authorization service, or by between the resource owner and an authorization service, or by
allowing the third-party application to obtain access on its own allowing the third-party application to obtain access on its own
behalf. This specification replaces and obsoletes the OAuth 2.0 behalf. This specification replaces and obsoletes the OAuth 2.0
Authorization Framework described in RFC 6749. Authorization Framework described in RFC 6749.
skipping to change at page 1, line 39 skipping to change at page 1, line 39
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.1. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 7 1.2. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 7
1.3. Authorization Grant . . . . . . . . . . . . . . . . . . . 8 1.3. Authorization Grant . . . . . . . . . . . . . . . . . . . 8
1.3.1. Authorization Code . . . . . . . . . . . . . . . . . 8 1.3.1. Authorization Code . . . . . . . . . . . . . . . . . 8
1.3.2. Client Credentials . . . . . . . . . . . . . . . . . 9 1.3.2. Refresh Token . . . . . . . . . . . . . . . . . . . . 9
1.4. Access Token . . . . . . . . . . . . . . . . . . . . . . 9 1.3.3. Client Credentials . . . . . . . . . . . . . . . . . 10
1.5. Refresh Token . . . . . . . . . . . . . . . . . . . . . . 10 1.4. Access Token . . . . . . . . . . . . . . . . . . . . . . 11
1.6. TLS Version . . . . . . . . . . . . . . . . . . . . . . . 12 1.5. TLS Version . . . . . . . . . . . . . . . . . . . . . . . 12
1.7. HTTP Redirections . . . . . . . . . . . . . . . . . . . . 12 1.6. HTTP Redirections . . . . . . . . . . . . . . . . . . . . 12
1.8. Interoperability . . . . . . . . . . . . . . . . . . . . 12 1.7. Interoperability . . . . . . . . . . . . . . . . . . . . 12
1.9. Compatibility with OAuth 2.0 . . . . . . . . . . . . . . 13 1.8. Compatibility with OAuth 2.0 . . . . . . . . . . . . . . 13
1.10. Notational Conventions . . . . . . . . . . . . . . . . . 13 1.9. Notational Conventions . . . . . . . . . . . . . . . . . 13
2. Client Registration . . . . . . . . . . . . . . . . . . . . . 14 2. Client Registration . . . . . . . . . . . . . . . . . . . . . 14
2.1. Client Types . . . . . . . . . . . . . . . . . . . . . . 14 2.1. Client Types . . . . . . . . . . . . . . . . . . . . . . 14
2.2. Client Identifier . . . . . . . . . . . . . . . . . . . . 16 2.2. Client Identifier . . . . . . . . . . . . . . . . . . . . 16
2.3. Client Authentication . . . . . . . . . . . . . . . . . . 16 2.3. Client Redirection Endpoint . . . . . . . . . . . . . . . 16
2.3.1. Client Secret . . . . . . . . . . . . . . . . . . . . 17 2.3.1. Endpoint Request Confidentiality . . . . . . . . . . 16
2.3.2. Other Authentication Methods . . . . . . . . . . . . 18 2.3.2. Registration Requirements . . . . . . . . . . . . . . 17
2.4. Unregistered Clients . . . . . . . . . . . . . . . . . . 18 2.3.3. Multiple Redirect URIs . . . . . . . . . . . . . . . 17
3. Protocol Endpoints . . . . . . . . . . . . . . . . . . . . . 18 2.3.4. Invalid Endpoint . . . . . . . . . . . . . . . . . . 17
3.1. Authorization Endpoint . . . . . . . . . . . . . . . . . 19 2.3.5. Endpoint Content . . . . . . . . . . . . . . . . . . 17
3.1.1. Response Type . . . . . . . . . . . . . . . . . . . . 19 2.4. Client Authentication . . . . . . . . . . . . . . . . . . 18
3.1.2. Redirection Endpoint . . . . . . . . . . . . . . . . 20 2.4.1. Client Secret . . . . . . . . . . . . . . . . . . . . 19
3.2. Token Endpoint . . . . . . . . . . . . . . . . . . . . . 22 2.4.2. Other Authentication Methods . . . . . . . . . . . . 20
2.5. Unregistered Clients . . . . . . . . . . . . . . . . . . 20
3. Protocol Endpoints . . . . . . . . . . . . . . . . . . . . . 20
3.1. Authorization Endpoint . . . . . . . . . . . . . . . . . 21
3.2. Token Endpoint . . . . . . . . . . . . . . . . . . . . . 21
3.2.1. Client Authentication . . . . . . . . . . . . . . . . 22 3.2.1. Client Authentication . . . . . . . . . . . . . . . . 22
3.3. Access Token Scope . . . . . . . . . . . . . . . . . . . 23 3.2.2. Token Request . . . . . . . . . . . . . . . . . . . . 22
4. Obtaining Authorization . . . . . . . . . . . . . . . . . . . 23 3.2.3. Token Response . . . . . . . . . . . . . . . . . . . 24
4.1. Authorization Code Grant . . . . . . . . . . . . . . . . 23 4. Grant Types . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.1.1. Authorization Request . . . . . . . . . . . . . . . . 25 4.1. Authorization Code Grant . . . . . . . . . . . . . . . . 28
4.1.2. Authorization Response . . . . . . . . . . . . . . . 28 4.1.1. Authorization Request . . . . . . . . . . . . . . . . 29
4.1.3. Access Token Request . . . . . . . . . . . . . . . . 31 4.1.2. Authorization Response . . . . . . . . . . . . . . . 32
4.1.4. Access Token Response . . . . . . . . . . . . . . . . 32 4.1.3. Token Endpoint Extension . . . . . . . . . . . . . . 35
4.2. Client Credentials Grant . . . . . . . . . . . . . . . . 32 4.2. Client Credentials Grant . . . . . . . . . . . . . . . . 36
4.2.1. Authorization Request and Response . . . . . . . . . 33 4.2.1. Token Endpoint Extension . . . . . . . . . . . . . . 37
4.2.2. Access Token Request . . . . . . . . . . . . . . . . 33 4.3. Refresh Token Grant . . . . . . . . . . . . . . . . . . . 38
4.2.3. Access Token Response . . . . . . . . . . . . . . . . 34 4.3.1. Token Endpoint Extension . . . . . . . . . . . . . . 38
4.3. Extension Grants . . . . . . . . . . . . . . . . . . . . 34 4.3.2. Refresh Token Response . . . . . . . . . . . . . . . 39
5. Issuing an Access Token . . . . . . . . . . . . . . . . . . . 35 4.4. Extension Grants . . . . . . . . . . . . . . . . . . . . 40
5.1. Successful Response . . . . . . . . . . . . . . . . . . . 35 5. Accessing Protected Resources . . . . . . . . . . . . . . . . 41
5.2. Error Response . . . . . . . . . . . . . . . . . . . . . 36 5.1. Access Token Types . . . . . . . . . . . . . . . . . . . 41
5.2. Bearer Tokens . . . . . . . . . . . . . . . . . . . . . . 42
5.2.1. Authenticated Requests . . . . . . . . . . . . . . . 42
5.2.2. The WWW-Authenticate Response Header Field . . . . . 44
5.2.3. Error Codes . . . . . . . . . . . . . . . . . . . . . 45
5.3. Error Response . . . . . . . . . . . . . . . . . . . . . 46
5.3.1. Extension Token Types . . . . . . . . . . . . . . . . 46
6. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 46
6.1. Defining Access Token Types . . . . . . . . . . . . . . . 47
6.2. Defining New Endpoint Parameters . . . . . . . . . . . . 47
6.3. Defining New Authorization Grant Types . . . . . . . . . 47
6.4. Defining New Authorization Endpoint Response Types . . . 48
6.5. Defining Additional Error Codes . . . . . . . . . . . . . 48
7. Security Considerations . . . . . . . . . . . . . . . . . . . 49
7.1. Access Token Security Considerations . . . . . . . . . . 49
7.1.1. Security Threats . . . . . . . . . . . . . . . . . . 49
7.1.2. Threat Mitigation . . . . . . . . . . . . . . . . . . 50
7.1.3. Summary of Recommendations . . . . . . . . . . . . . 52
7.1.4. Token Replay Prevention . . . . . . . . . . . . . . . 53
7.1.5. Access Token Privilege Restriction . . . . . . . . . 54
7.2. Client Authentication . . . . . . . . . . . . . . . . . . 54
7.2.1. Client Authentication of Native Apps . . . . . . . . 55
7.3. Registration of Native App Clients . . . . . . . . . . . 55
7.4. Client Impersonation . . . . . . . . . . . . . . . . . . 56
7.4.1. Impersonation of Native Apps . . . . . . . . . . . . 56
7.4.2. Access Token Privilege Restriction . . . . . . . . . 57
7.4.3. Access Token Replay Prevention . . . . . . . . . . . 57
7.5. Refresh Tokens . . . . . . . . . . . . . . . . . . . . . 58
7.6. Client Impersonating Resource Owner . . . . . . . . . . . 58
7.7. Protecting the Authorization Code Flow . . . . . . . . . 59
7.7.1. Loopback Redirect Considerations in Native Apps . . . 59
7.7.2. HTTP 307 Redirect . . . . . . . . . . . . . . . . . . 60
7.8. Authorization Codes . . . . . . . . . . . . . . . . . . . 61
7.9. Request Confidentiality . . . . . . . . . . . . . . . . . 62
7.10. Ensuring Endpoint Authenticity . . . . . . . . . . . . . 62
7.11. Credentials-Guessing Attacks . . . . . . . . . . . . . . 62
7.12. Phishing Attacks . . . . . . . . . . . . . . . . . . . . 63
7.13. Fake External User-Agents in Native Apps . . . . . . . . 63
7.14. Malicious External User-Agents in Native Apps . . . . . . 64
7.15. Cross-Site Request Forgery . . . . . . . . . . . . . . . 64
7.16. Clickjacking . . . . . . . . . . . . . . . . . . . . . . 65
7.17. Code Injection and Input Validation . . . . . . . . . . . 66
7.18. Open Redirectors . . . . . . . . . . . . . . . . . . . . 66
7.18.1. Client as Open Redirector . . . . . . . . . . . . . 66
7.18.2. Authorization Server as Open Redirector . . . . . . 66
6. Refreshing an Access Token . . . . . . . . . . . . . . . . . 38 7.19. Authorization Server Mix-Up Mitigation in Native Apps . . 67
6.1. Refresh Token Request . . . . . . . . . . . . . . . . . . 38 7.20. Embedded User Agents in Native Apps . . . . . . . . . . . 67
6.2. Refresh Token Response . . . . . . . . . . . . . . . . . 40 7.21. Other Recommendations . . . . . . . . . . . . . . . . . . 68
7. Accessing Protected Resources . . . . . . . . . . . . . . . . 41 8. Native Applications . . . . . . . . . . . . . . . . . . . . . 68
7.1. Access Token Types . . . . . . . . . . . . . . . . . . . 41 8.1. Using Inter-App URI Communication for OAuth in Native
7.2. Bearer Tokens . . . . . . . . . . . . . . . . . . . . . . 42 Apps . . . . . . . . . . . . . . . . . . . . . . . . . . 69
7.2.1. Authenticated Requests . . . . . . . . . . . . . . . 42 8.2. Initiating the Authorization Request from a Native App . 70
7.2.2. The WWW-Authenticate Response Header Field . . . . . 44 8.3. Receiving the Authorization Response in a Native App . . 70
7.2.3. Error Codes . . . . . . . . . . . . . . . . . . . . . 45 8.3.1. Private-Use URI Scheme Redirection . . . . . . . . . 71
7.3. Error Response . . . . . . . . . . . . . . . . . . . . . 46 8.3.2. Claimed "https" Scheme URI Redirection . . . . . . . 72
7.3.1. Extension Token Types . . . . . . . . . . . . . . . . 46 8.3.3. Loopback Interface Redirection . . . . . . . . . . . 72
7.4. Access Token Security Considerations . . . . . . . . . . 46 9. Browser-Based Apps . . . . . . . . . . . . . . . . . . . . . 73
7.4.1. Security Threats . . . . . . . . . . . . . . . . . . 47 10. Differences from OAuth 2.0 . . . . . . . . . . . . . . . . . 73
7.4.2. Threat Mitigation . . . . . . . . . . . . . . . . . . 47 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 74
7.4.3. Summary of Recommendations . . . . . . . . . . . . . 49 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 74
7.4.4. Token Replay Prevention . . . . . . . . . . . . . . . 50 12.1. Normative References . . . . . . . . . . . . . . . . . . 74
7.4.5. Access Token Privilege Restriction . . . . . . . . . 51 12.2. Informative References . . . . . . . . . . . . . . . . . 77
8. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 51
8.1. Defining Access Token Types . . . . . . . . . . . . . . . 51
8.2. Defining New Endpoint Parameters . . . . . . . . . . . . 52
8.3. Defining New Authorization Grant Types . . . . . . . . . 52
8.4. Defining New Authorization Endpoint Response Types . . . 52
8.5. Defining Additional Error Codes . . . . . . . . . . . . . 53
9. Security Considerations . . . . . . . . . . . . . . . . . . . 53
9.1. Client Authentication . . . . . . . . . . . . . . . . . . 54
9.1.1. Client Authentication of Native Apps . . . . . . . . 54
9.2. Registration of Native App Clients . . . . . . . . . . . 55
9.3. Client Impersonation . . . . . . . . . . . . . . . . . . 55
9.3.1. Impersonation of Native Apps . . . . . . . . . . . . 56
9.4. Access Tokens . . . . . . . . . . . . . . . . . . . . . . 56
9.4.1. Access Token Privilege Restriction . . . . . . . . . 57
9.4.2. Access Token Replay Prevention . . . . . . . . . . . 57
9.5. Refresh Tokens . . . . . . . . . . . . . . . . . . . . . 58
9.6. Client Impersonating Resource Owner . . . . . . . . . . . 58
9.7. Protecting Redirect-Based Flows . . . . . . . . . . . . . 59
9.7.1. Loopback Redirect Considerations in Native Apps . . . 59
9.7.2. HTTP 307 Redirect . . . . . . . . . . . . . . . . . . 60
9.8. Authorization Codes . . . . . . . . . . . . . . . . . . . 61
9.9. Request Confidentiality . . . . . . . . . . . . . . . . . 62
9.10. Ensuring Endpoint Authenticity . . . . . . . . . . . . . 62
9.11. Credentials-Guessing Attacks . . . . . . . . . . . . . . 63
9.12. Phishing Attacks . . . . . . . . . . . . . . . . . . . . 63
9.13. Fake External User-Agents in Native Apps . . . . . . . . 63
9.14. Malicious External User-Agents in Native Apps . . . . . . 64
9.15. Cross-Site Request Forgery . . . . . . . . . . . . . . . 64
9.16. Clickjacking . . . . . . . . . . . . . . . . . . . . . . 65
9.17. Code Injection and Input Validation . . . . . . . . . . . 66
9.18. Open Redirectors . . . . . . . . . . . . . . . . . . . . 66
9.18.1. Client as Open Redirector . . . . . . . . . . . . . 66
9.18.2. Authorization Server as Open Redirector . . . . . . 66
9.19. Authorization Server Mix-Up Mitigation in Native Apps . . 67
9.20. Embedded User Agents in Native Apps . . . . . . . . . . . 67
9.21. Other Recommendations . . . . . . . . . . . . . . . . . . 68
10. Native Applications . . . . . . . . . . . . . . . . . . . . . 68
10.1. Using Inter-App URI Communication for OAuth in Native
Apps . . . . . . . . . . . . . . . . . . . . . . . . . . 69
10.2. Initiating the Authorization Request from a Native
App . . . . . . . . . . . . . . . . . . . . . . . . . . 70
10.3. Receiving the Authorization Response in a Native App . . 71
10.3.1. Private-Use URI Scheme Redirection . . . . . . . . . 71
10.3.2. Claimed "https" Scheme URI Redirection . . . . . . . 72
10.3.3. Loopback Interface Redirection . . . . . . . . . . . 72
11. Browser-Based Apps . . . . . . . . . . . . . . . . . . . . . 73
12. Differences from OAuth 2.0 . . . . . . . . . . . . . . . . . 73
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 74
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 74
14.1. Normative References . . . . . . . . . . . . . . . . . . 74
14.2. Informative References . . . . . . . . . . . . . . . . . 77
Appendix A. Augmented Backus-Naur Form (ABNF) Syntax . . . . . . 80 Appendix A. Augmented Backus-Naur Form (ABNF) Syntax . . . . . . 80
A.1. "client_id" Syntax . . . . . . . . . . . . . . . . . . . 81 A.1. "client_id" Syntax . . . . . . . . . . . . . . . . . . . 80
A.2. "client_secret" Syntax . . . . . . . . . . . . . . . . . 81 A.2. "client_secret" Syntax . . . . . . . . . . . . . . . . . 80
A.3. "response_type" Syntax . . . . . . . . . . . . . . . . . 81 A.3. "response_type" Syntax . . . . . . . . . . . . . . . . . 80
A.4. "scope" Syntax . . . . . . . . . . . . . . . . . . . . . 81 A.4. "scope" Syntax . . . . . . . . . . . . . . . . . . . . . 81
A.5. "state" Syntax . . . . . . . . . . . . . . . . . . . . . 81 A.5. "state" Syntax . . . . . . . . . . . . . . . . . . . . . 81
A.6. "redirect_uri" Syntax . . . . . . . . . . . . . . . . . . 81 A.6. "redirect_uri" Syntax . . . . . . . . . . . . . . . . . . 81
A.7. "error" Syntax . . . . . . . . . . . . . . . . . . . . . 81 A.7. "error" Syntax . . . . . . . . . . . . . . . . . . . . . 81
A.8. "error_description" Syntax . . . . . . . . . . . . . . . 82 A.8. "error_description" Syntax . . . . . . . . . . . . . . . 81
A.9. "error_uri" Syntax . . . . . . . . . . . . . . . . . . . 82 A.9. "error_uri" Syntax . . . . . . . . . . . . . . . . . . . 81
A.10. "grant_type" Syntax . . . . . . . . . . . . . . . . . . . 82 A.10. "grant_type" Syntax . . . . . . . . . . . . . . . . . . . 81
A.11. "code" Syntax . . . . . . . . . . . . . . . . . . . . . . 82 A.11. "code" Syntax . . . . . . . . . . . . . . . . . . . . . . 82
A.12. "access_token" Syntax . . . . . . . . . . . . . . . . . . 82 A.12. "access_token" Syntax . . . . . . . . . . . . . . . . . . 82
A.13. "token_type" Syntax . . . . . . . . . . . . . . . . . . . 82 A.13. "token_type" Syntax . . . . . . . . . . . . . . . . . . . 82
A.14. "expires_in" Syntax . . . . . . . . . . . . . . . . . . . 82 A.14. "expires_in" Syntax . . . . . . . . . . . . . . . . . . . 82
A.15. "refresh_token" Syntax . . . . . . . . . . . . . . . . . 83 A.15. "refresh_token" Syntax . . . . . . . . . . . . . . . . . 82
A.16. Endpoint Parameter Syntax . . . . . . . . . . . . . . . . 83 A.16. Endpoint Parameter Syntax . . . . . . . . . . . . . . . . 82
A.17. "code_verifier" Syntax . . . . . . . . . . . . . . . . . 83 A.17. "code_verifier" Syntax . . . . . . . . . . . . . . . . . 83
A.18. "code_challenge" Syntax . . . . . . . . . . . . . . . . . 83 A.18. "code_challenge" Syntax . . . . . . . . . . . . . . . . . 83
Appendix B. Use of application/x-www-form-urlencoded Media Appendix B. Use of application/x-www-form-urlencoded Media
Type . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Type . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Appendix C. Extensions . . . . . . . . . . . . . . . . . . . . . 84 Appendix C. Extensions . . . . . . . . . . . . . . . . . . . . . 84
Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 86 Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 85
Appendix E. Document History . . . . . . . . . . . . . . . . . . 85
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 86
1. Introduction 1. Introduction
In the traditional client-server authentication model, the client In the traditional client-server authentication model, the client
requests an access-restricted resource (protected resource) on the requests an access-restricted resource (protected resource) on the
server by authenticating with the server using the resource owner's server by authenticating with the server using the resource owner's
credentials. In order to provide third-party applications access to credentials. In order to provide third-party applications access to
restricted resources, the resource owner shares its credentials with restricted resources, the resource owner shares its credentials with
the third party. This creates several problems and limitations: the third party. This creates several problems and limitations:
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ability to restrict duration or access to a limited subset of ability to restrict duration or access to a limited subset of
resources. resources.
* Resource owners often reuse passwords with other unrelated * Resource owners often reuse passwords with other unrelated
services, despite best security practices. This password reuse services, despite best security practices. This password reuse
means a vulnerability or exposure in one service may have security means a vulnerability or exposure in one service may have security
implications in completely unrelated services. implications in completely unrelated services.
* Resource owners cannot revoke access to an individual third party * Resource owners cannot revoke access to an individual third party
without revoking access to all third parties, and must do so by without revoking access to all third parties, and must do so by
changing the third party's password. changing their password.
* Compromise of any third-party application results in compromise of * Compromise of any third-party application results in compromise of
the end-user's password and all of the data protected by that the end-user's password and all of the data protected by that
password. password.
OAuth addresses these issues by introducing an authorization layer OAuth addresses these issues by introducing an authorization layer
and separating the role of the client from that of the resource and separating the role of the client from that of the resource
owner. In OAuth, the client requests access to resources controlled owner. In OAuth, the client requests access to resources controlled
by the resource owner and hosted by the resource server. Instead of by the resource owner and hosted by the resource server. Instead of
using the resource owner's credentials to access protected resources, using the resource owner's credentials to access protected resources,
the client obtains an access token - a credential representing a the client obtains an access token - a credential representing a
specific set of access attributes such as scope and lifetime. Access specific set of access attributes such as scope and lifetime. Access
tokens are issued to clients by an authorization server with the tokens are issued to clients by an authorization server with the
approval of the resource owner. The client uses the access token to approval of the resource owner. The client uses the access token to
access the protected resources hosted by the resource server. access the protected resources hosted by the resource server.
For example, an end-user (resource owner) can grant a printing For example, an end-user (resource owner) can grant a printing
service (client) access to their protected photos stored at a photo- service (client) access to their protected photos stored at a photo-
sharing service (resource server), without sharing their username and sharing service (resource server), without sharing their username and
password with the printing service. Instead, they authenticates password with the printing service. Instead, they authenticate
directly with a server trusted by the photo-sharing service directly with a server trusted by the photo-sharing service
(authorization server), which issues the printing service delegation- (authorization server), which issues the printing service delegation-
specific credentials (access token). specific credentials (access token).
This specification is designed for use with HTTP ([RFC7230]). The This specification is designed for use with HTTP ([RFC7231]). The
use of OAuth over any protocol other than HTTP is out of scope. use of OAuth over any protocol other than HTTP is out of scope.
Since the publication of the OAuth 2.0 Authorization Framework Since the publication of the OAuth 2.0 Authorization Framework
([RFC6749]) in October 2012, it has been updated by OAuth 2.0 for ([RFC6749]) in October 2012, it has been updated by OAuth 2.0 for
Native Apps ([RFC8252]), OAuth Security Best Current Practice Native Apps ([RFC8252]), OAuth Security Best Current Practice
([I-D.ietf-oauth-security-topics]), and OAuth 2.0 for Browser-Based ([I-D.ietf-oauth-security-topics]), and OAuth 2.0 for Browser-Based
Apps ([I-D.ietf-oauth-browser-based-apps]). The OAuth 2.0 Apps ([I-D.ietf-oauth-browser-based-apps]). The OAuth 2.0
Authorization Framework: Bearer Token Usage ([RFC6750]) has also been Authorization Framework: Bearer Token Usage ([RFC6750]) has also been
updated with ([I-D.ietf-oauth-security-topics]). This Standards updated with ([I-D.ietf-oauth-security-topics]). This Standards
Track specification consolidates the information in all of these Track specification consolidates the information in all of these
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behalf of the resource owner and with its authorization. The term behalf of the resource owner and with its authorization. The term
"client" does not imply any particular implementation "client" does not imply any particular implementation
characteristics (e.g., whether the application executes on a characteristics (e.g., whether the application executes on a
server, a desktop, or other devices). server, a desktop, or other devices).
"authorization server": The server issuing access tokens to the "authorization server": The server issuing access tokens to the
client after successfully authenticating the resource owner and client after successfully authenticating the resource owner and
obtaining authorization. This is sometimes abbreviated as "AS". obtaining authorization. This is sometimes abbreviated as "AS".
The interaction between the authorization server and resource server The interaction between the authorization server and resource server
is beyond the scope of this specification, however several extension is beyond the scope of this specification, however several extensions
have been defined to provide an option for interoperability between have been defined to provide an option for interoperability between
resource servers and authorization servers. The authorization server resource servers and authorization servers. The authorization server
may be the same server as the resource server or a separate entity. may be the same server as the resource server or a separate entity.
A single authorization server may issue access tokens accepted by A single authorization server may issue access tokens accepted by
multiple resource servers. multiple resource servers.
1.2. Protocol Flow 1.2. Protocol Flow
+--------+ +---------------+ +--------+ +---------------+
| |--(1)- Authorization Request ->| Resource | | |--(1)- Authorization Request ->| Resource |
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The abstract OAuth 2.1 flow illustrated in Figure 1 describes the The abstract OAuth 2.1 flow illustrated in Figure 1 describes the
interaction between the four roles and includes the following steps: interaction between the four roles and includes the following steps:
1. The client requests authorization from the resource owner. The 1. The client requests authorization from the resource owner. The
authorization request can be made directly to the resource owner authorization request can be made directly to the resource owner
(as shown), or preferably indirectly via the authorization server (as shown), or preferably indirectly via the authorization server
as an intermediary. as an intermediary.
2. The client receives an authorization grant, which is a credential 2. The client receives an authorization grant, which is a credential
representing the resource owner's authorization, expressed using representing the resource owner's authorization, expressed using
one of two authorization grant types defined in this one of the authorization grant types defined in this
specification or using an extension grant type. The specification or using an extension grant type. The
authorization grant type depends on the method used by the client authorization grant type depends on the method used by the client
to request authorization and the types supported by the to request authorization and the types supported by the
authorization server. authorization server.
3. The client requests an access token by authenticating with the 3. The client requests an access token by authenticating with the
authorization server and presenting the authorization grant. authorization server and presenting the authorization grant.
4. The authorization server authenticates the client and validates 4. The authorization server authenticates the client and validates
the authorization grant, and if valid, issues an access token. the authorization grant, and if valid, issues an access token.
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The preferred method for the client to obtain an authorization grant The preferred method for the client to obtain an authorization grant
from the resource owner (depicted in steps (1) and (2)) is to use the from the resource owner (depicted in steps (1) and (2)) is to use the
authorization server as an intermediary, which is illustrated in authorization server as an intermediary, which is illustrated in
Figure 3 in Section 4.1. Figure 3 in Section 4.1.
1.3. Authorization Grant 1.3. Authorization Grant
An authorization grant is a credential representing the resource An authorization grant is a credential representing the resource
owner's authorization (to access its protected resources) used by the owner's authorization (to access its protected resources) used by the
client to obtain an access token. This specification defines two client to obtain an access token. This specification defines three
grant types - authorization code and client credentials - as well as grant types - authorization code, refresh token, and client
an extensibility mechanism for defining additional types. credentials - as well as an extensibility mechanism for defining
additional types.
1.3.1. Authorization Code 1.3.1. Authorization Code
An authorization code is a temporary credential used to obtain an An authorization code is a temporary credential used to obtain an
access token. Instead of the client requesting authorization access token. Instead of the client requesting authorization
directly from the resource owner, the client directs the resource directly from the resource owner, the client directs the resource
owner to an authorization server (via its user-agent as defined in owner to an authorization server (via its user agent, which in turn
[RFC7231]), which in turn directs the resource owner back to the directs the resource owner back to the client with the authorization
client with the authorization code. The client can then exchange the code. The client can then exchange the authorization code for an
authorization code for an access token. access token.
Before directing the resource owner back to the client with the Before directing the resource owner back to the client with the
authorization code, the authorization server authenticates the authorization code, the authorization server authenticates the
resource owner, and may request the resource owner's consent or resource owner, and may request the resource owner's consent or
otherwise inform them of the client's request. Because the resource otherwise inform them of the client's request. Because the resource
owner only authenticates with the authorization server, the resource owner only authenticates with the authorization server, the resource
owner's credentials are never shared with the client, and the client owner's credentials are never shared with the client, and the client
does not need to have knowledge of any additional authentication does not need to have knowledge of any additional authentication
steps such as multi-factor authentication or delegated accounts. steps such as multi-factor authentication or delegated accounts.
The authorization code provides a few important security benefits, The authorization code provides a few important security benefits,
such as the ability to authenticate the client, as well as the such as the ability to authenticate the client, as well as the
transmission of the access token directly to the client without transmission of the access token directly to the client without
passing it through the resource owner's user-agent and potentially passing it through the resource owner's user agent and potentially
exposing it to others, including the resource owner. exposing it to others, including the resource owner.
1.3.2. Client Credentials 1.3.2. Refresh Token
The client credentials or other forms of client authentication (e.g.
a "client_secret" or a private key used to sign a JWT) can be used as
an authorization grant when the authorization scope is limited to the
protected resources under the control of the client, or to protected
resources previously arranged with the authorization server. Client
credentials are used as an authorization grant typically when the
client is acting on its own behalf (the client is also the resource
owner) or is requesting access to protected resources based on an
authorization previously arranged with the authorization server.
1.4. Access Token
Access tokens are credentials used to access protected resources. An
access token is a string representing an authorization issued to the
client. The string is considered opaque to the client, even if it
has a structure. Depending on the authorization server, the access
token string may be parseable by the resource server.
Access tokens represent specific scopes and durations of access,
granted by the resource owner, and enforced by the resource server
and authorization server.
The token may be used by the RS to retrieve the authorization
information, or the token may self-contain the authorization
information in a verifiable manner (i.e., a token string consisting
of a signed data payload). One example of a token retrieval
mechanism is Token Introspection [RFC7662], in which the RS calls an
endpoint on the AS to validate the token presented by the client.
One example of a structured token format is
[I-D.ietf-oauth-access-token-jwt], a method of encoding access token
data as a JSON Web Token [RFC7519].
Additional authentication credentials, which are beyond the scope of
this specification, may be required in order for the client to use an
access token. This is typically referred to as a sender-constrained
access token, such as Mutual TLS Access Tokens [RFC8705].
The access token provides an abstraction layer, replacing different
authorization constructs (e.g., username and password) with a single
token understood by the resource server. This abstraction enables
issuing access tokens more restrictive than the authorization grant
used to obtain them, as well as removing the resource server's need
to understand a wide range of authentication methods.
Access tokens can have different formats, structures, and methods of
utilization (e.g., cryptographic properties) based on the resource
server security requirements. Access token attributes and the
methods used to access protected resources may be extended beyond
what is described in this specification.
1.5. Refresh Token
Refresh tokens are credentials used to obtain access tokens. Refresh Refresh tokens are credentials used to obtain access tokens. Refresh
tokens are issued to the client by the authorization server and are tokens are issued to the client by the authorization server and are
used to obtain a new access token when the current access token used to obtain a new access token when the current access token
becomes invalid or expires, or to obtain additional access tokens becomes invalid or expires, or to obtain additional access tokens
with identical or narrower scope (access tokens may have a shorter with identical or narrower scope (access tokens may have a shorter
lifetime and fewer permissions than authorized by the resource lifetime and fewer permissions than authorized by the resource
owner). Issuing a refresh token is optional at the discretion of the owner). Issuing a refresh token is optional at the discretion of the
authorization server, and may be issued based on properties of the authorization server, and may be issued based on properties of the
client, properties of the request, policies within the authorization client, properties of the request, policies within the authorization
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7. The client requests a new access token by presenting the refresh 7. The client requests a new access token by presenting the refresh
token and providing client authentication if it has been issued token and providing client authentication if it has been issued
credentials. The client authentication requirements are based on credentials. The client authentication requirements are based on
the client type and on the authorization server policies. the client type and on the authorization server policies.
8. The authorization server authenticates the client and validates 8. The authorization server authenticates the client and validates
the refresh token, and if valid, issues a new access token (and, the refresh token, and if valid, issues a new access token (and,
optionally, a new refresh token). optionally, a new refresh token).
1.6. TLS Version 1.3.3. Client Credentials
The client credentials or other forms of client authentication (e.g.
a "client_secret" or a private key used to sign a JWT) can be used as
an authorization grant when the authorization scope is limited to the
protected resources under the control of the client, or to protected
resources previously arranged with the authorization server. Client
credentials are used as an authorization grant typically when the
client is acting on its own behalf (the client is also the resource
owner) or is requesting access to protected resources based on an
authorization previously arranged with the authorization server.
1.4. Access Token
Access tokens are credentials used to access protected resources. An
access token is a string representing an authorization issued to the
client. The string is considered opaque to the client, even if it
has a structure. Depending on the authorization server, the access
token string may be parseable by the resource server, such as when
using the JSON Web Token Profile for Access Tokens
([I-D.ietf-oauth-access-token-jwt]).
Access tokens represent specific scopes and durations of access,
granted by the resource owner, and enforced by the resource server
and authorization server.
The token may be used by the RS to retrieve the authorization
information, or the token may self-contain the authorization
information in a verifiable manner (i.e., a token string consisting
of a signed data payload). One example of a token retrieval
mechanism is Token Introspection [RFC7662], in which the RS calls an
endpoint on the AS to validate the token presented by the client.
One example of a structured token format is
[I-D.ietf-oauth-access-token-jwt], a method of encoding access token
data as a JSON Web Token [RFC7519].
Additional authentication credentials, which are beyond the scope of
this specification, may be required in order for the client to use an
access token. This is typically referred to as a sender-constrained
access token, such as Mutual TLS Access Tokens [RFC8705].
The access token provides an abstraction layer, replacing different
authorization constructs (e.g., username and password) with a single
token understood by the resource server. This abstraction enables
issuing access tokens more restrictive than the authorization grant
used to obtain them, as well as removing the resource server's need
to understand a wide range of authentication methods.
Access tokens can have different formats, structures, and methods of
utilization (e.g., cryptographic properties) based on the resource
server security requirements. Access token attributes and the
methods used to access protected resources may be extended beyond
what is described in this specification.
Access tokens (as well as any confidential access token attributes)
MUST be kept confidential in transit and storage, and only shared
among the authorization server, the resource servers the access token
is valid for, and the client to whom the access token is issued.
Access token credentials MUST only be transmitted using TLS as
described in Section 1.5 with server authentication as defined by
[RFC2818].
The authorization server MUST ensure that access tokens cannot be
generated, modified, or guessed to produce valid access tokens by
unauthorized parties.
1.5. TLS Version
Whenever Transport Layer Security (TLS) is used by this Whenever Transport Layer Security (TLS) is used by this
specification, the appropriate version (or versions) of TLS will vary specification, the appropriate version (or versions) of TLS will vary
over time, based on the widespread deployment and known security over time, based on the widespread deployment and known security
vulnerabilities. Refer to [BCP195] for up to date recommendations on vulnerabilities. Refer to [BCP195] for up to date recommendations on
transport layer security. transport layer security.
Implementations MAY also support additional transport-layer security Implementations MAY also support additional transport-layer security
mechanisms that meet their security requirements. mechanisms that meet their security requirements.
1.7. HTTP Redirections 1.6. HTTP Redirections
This specification makes extensive use of HTTP redirections, in which This specification makes extensive use of HTTP redirections, in which
the client or the authorization server directs the resource owner's the client or the authorization server directs the resource owner's
user-agent to another destination. While the examples in this user agent to another destination. While the examples in this
specification show the use of the HTTP 302 status code, any other specification show the use of the HTTP 302 status code, any other
method available via the user-agent to accomplish this redirection, method available via the user agent to accomplish this redirection,
with the exception of HTTP 307, is allowed and is considered to be an with the exception of HTTP 307, is allowed and is considered to be an
implementation detail. See Section 9.7.2 for details. implementation detail. See Section 7.7.2 for details.
1.8. Interoperability 1.7. Interoperability
OAuth 2.1 provides a rich authorization framework with well-defined OAuth 2.1 provides a rich authorization framework with well-defined
security properties. security properties.
This specification leaves a few required components partially or This specification leaves a few required components partially or
fully undefined (e.g., client registration, authorization server fully undefined (e.g., client registration, authorization server
capabilities, endpoint discovery). Some of these behaviors are capabilities, endpoint discovery). Some of these behaviors are
defined in optional extensions which implementations can choose to defined in optional extensions which implementations can choose to
use, such as: use, such as:
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* [RFC7592]: Dynamic Client Management, providing a mechanism for * [RFC7592]: Dynamic Client Management, providing a mechanism for
updating dynamically registered client information updating dynamically registered client information
* [RFC7662]: Token Introspection, defining a mechanism for resource * [RFC7662]: Token Introspection, defining a mechanism for resource
servers to obtain information about access tokens servers to obtain information about access tokens
Please refer to Appendix C for a list of current known extensions at Please refer to Appendix C for a list of current known extensions at
the time of this publication. the time of this publication.
1.9. Compatibility with OAuth 2.0 1.8. Compatibility with OAuth 2.0
OAuth 2.1 is compatible with OAuth 2.0 with the extensions and OAuth 2.1 is compatible with OAuth 2.0 with the extensions and
restrictions from known best current practices applied. restrictions from known best current practices applied.
Specifically, features not specified in OAuth 2.0 core, such as PKCE, Specifically, features not specified in OAuth 2.0 core, such as PKCE,
are required in OAuth 2.1. Additionally, some features available in are required in OAuth 2.1. Additionally, some features available in
OAuth 2.0, such as the Implicit or Resource Owner Credentials grant OAuth 2.0, such as the Implicit or Resource Owner Credentials grant
types, are not specified in OAuth 2.1. Furthermore, some behaviors types, are not specified in OAuth 2.1. Furthermore, some behaviors
allowed in OAuth 2.0 are restricted in OAuth 2.1, such as the strict allowed in OAuth 2.0 are restricted in OAuth 2.1, such as the strict
string matching of redirect URIs required by OAuth 2.1. string matching of redirect URIs required by OAuth 2.1.
See Section 12 for more details on the differences from OAuth 2.0. See Section 10 for more details on the differences from OAuth 2.0.
1.10. Notational Conventions 1.9. Notational Conventions
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 BCP "OPTIONAL" in this document are to be interpreted as described in
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 specification uses the Augmented Backus-Naur Form (ABNF) This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234]. Additionally, the rule URI-reference is notation of [RFC5234]. Additionally, the rule URI-reference is
included from "Uniform Resource Identifier (URI): Generic Syntax" included from "Uniform Resource Identifier (URI): Generic Syntax"
[RFC3986]. [RFC3986].
Certain security-related terms are to be understood in the sense Certain security-related terms are to be understood in the sense
defined in [RFC4949]. These terms include, but are not limited to, defined in [RFC4949]. These terms include, but are not limited to,
"attack", "authentication", "authorization", "certificate", "attack", "authentication", "authorization", "certificate",
"confidentiality", "credential", "encryption", "identity", "sign", "confidentiality", "credential", "encryption", "identity", "sign",
"signature", "trust", "validate", and "verify". "signature", "trust", "validate", and "verify".
The term "payload" is to be interpreted as described in Section 3.3 The term "payload" is to be interpreted as described in Section 3.3
of [RFC7231]. of [RFC7231].
The term "user agent" is to be interpreted as described in [RFC7230].
Unless otherwise noted, all the protocol parameter names and values Unless otherwise noted, all the protocol parameter names and values
are case sensitive. are case sensitive.
2. Client Registration 2. Client Registration
Before initiating the protocol, the client must establish its Before initiating the protocol, the client must establish its
registration with the authorization server. The means through which registration with the authorization server. The means through which
the client registers with the authorization server are beyond the the client registers with the authorization server are beyond the
scope of this specification but typically involve the client scope of this specification but typically involve the client
developer manually registering the client at the authorization developer manually registering the client at the authorization
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(e.g., redirect URI, client type). For example, registration can be (e.g., redirect URI, client type). For example, registration can be
accomplished using a self-issued or third-party-issued assertion, or accomplished using a self-issued or third-party-issued assertion, or
by the authorization server performing client discovery using a by the authorization server performing client discovery using a
trusted channel. trusted channel.
When registering a client, the client developer SHALL: When registering a client, the client developer SHALL:
* specify the client type as described in Section 2.1, * specify the client type as described in Section 2.1,
* provide client details needed by the grant type in use, such as * provide client details needed by the grant type in use, such as
redirect URIs as described in Section 3.1.2, and redirect URIs as described in Section 2.3, and
* include any other information required by the authorization server * include any other information required by the authorization server
(e.g., application name, website, description, logo image, the (e.g., application name, website, description, logo image, the
acceptance of legal terms). acceptance of legal terms).
Dynamic Client Registration ([RFC7591]) defines a common general data Dynamic Client Registration ([RFC7591]) defines a common general data
model for clients that may be used even with manual client model for clients that may be used even with manual client
registration. registration.
2.1. Client Types 2.1. Client Types
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grant type. grant type.
A single "client_id" MUST NOT be treated as more than one type of A single "client_id" MUST NOT be treated as more than one type of
client. client.
This specification has been designed around the following client This specification has been designed around the following client
profiles: profiles:
"web application": A web application is a confidential client "web application": A web application is a confidential client
running on a web server. Resource owners access the client via an running on a web server. Resource owners access the client via an
HTML user interface rendered in a user-agent on the device used by HTML user interface rendered in a user agent on the device used by
the resource owner. The client credentials as well as any access the resource owner. The client credentials as well as any access
token issued to the client are stored on the web server and are tokens issued to the client are stored on the web server and are
not exposed to or accessible by the resource owner. not exposed to or accessible by the resource owner.
"browser-based application": A browser-based application is a public "browser-based application": A browser-based application is a public
client in which the client code is downloaded from a web server client in which the client code is downloaded from a web server
and executes within a user-agent (e.g., web browser) on the device and executes within a user agent (e.g., web browser) on the device
used by the resource owner. Protocol data and credentials are used by the resource owner. Protocol data and credentials are
easily accessible (and often visible) to the resource owner. easily accessible (and often visible) to the resource owner.
Since such applications reside within the user-agent, they can Since such applications reside within the user agent, they can
make seamless use of the user-agent capabilities when requesting make seamless use of the user agent capabilities when requesting
authorization. authorization.
"native application": A native application is a public client "native application": A native application is a public client
installed and executed on the device used by the resource owner. installed and executed on the device used by the resource owner.
Protocol data and credentials are accessible to the resource Protocol data and credentials are accessible to the resource
owner. It is assumed that any client authentication credentials owner. It is assumed that any client authentication credentials
included in the application can be extracted. On the other hand, included in the application can be extracted. On the other hand,
dynamically issued credentials such as access tokens or refresh dynamically issued credentials such as access tokens or refresh
tokens can receive an acceptable level of protection. At a tokens can receive an acceptable level of protection. At a
minimum, these credentials are protected from hostile servers with minimum, these credentials are protected from hostile servers with
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secret; it is exposed to the resource owner and MUST NOT be used secret; it is exposed to the resource owner and MUST NOT be used
alone for client authentication. The client identifier is unique to alone for client authentication. The client identifier is unique to
the authorization server. the authorization server.
The client identifier string size is left undefined by this The client identifier string size is left undefined by this
specification. The client should avoid making assumptions about the specification. The client should avoid making assumptions about the
identifier size. The authorization server SHOULD document the size identifier size. The authorization server SHOULD document the size
of any identifier it issues. of any identifier it issues.
Authorization servers SHOULD NOT allow clients to choose or influence Authorization servers SHOULD NOT allow clients to choose or influence
their "client_id" value. See Section 9.6 for details. their "client_id" value. See Section 7.6 for details.
2.3. Client Authentication 2.3. Client Redirection Endpoint
The client redirection endpoint (also referred to as "redirect
endpoint") is the URI of the client that the authorization server
redirects the user agent back to after completing its interaction
with the resource owner.
The authorization server redirects the user agent to one of the
client's redirection endpoints previously established with the
authorization server during the client registration process.
The redirect URI MUST be an absolute URI as defined by [RFC3986]
Section 4.3. The endpoint URI MAY include an "application/x-www-
form-urlencoded" formatted (per Appendix B) query component
([RFC3986] Section 3.4), which MUST be retained when adding
additional query parameters. The endpoint URI MUST NOT include a
fragment component.
2.3.1. Endpoint Request Confidentiality
The redirection endpoint SHOULD require the use of TLS as described
in Section 1.5 when the requested response type is "code", or when
the redirection request will result in the transmission of sensitive
credentials over an open network. If TLS is not available, the
authorization server SHOULD warn the resource owner about the
insecure endpoint prior to redirection (e.g., display a message
during the authorization request).
2.3.2. Registration Requirements
Authorization servers MUST require clients to register their complete
redirect URI (including the path component) and reject authorization
requests that specify a redirect URI that doesn't exactly match one
that was registered; the exception is loopback redirects, where an
exact match is required except for the port URI component.
For private-use URI scheme-based redirect URIs, authorization servers
SHOULD enforce the requirement in Section 8.3.1 that clients use
schemes that are reverse domain name based. At a minimum, any
private-use URI scheme that doesn't contain a period character (".")
SHOULD be rejected.
The client MAY use the "state" request parameter to achieve per-
request customization if needed rather than varying the redirect URI
per request.
The authorization server MAY allow the client to register multiple
redirect URIs.
Without requiring registration of redirect URIs, attackers can use
the authorization endpoint as an open redirector as described in
Section 7.18.
2.3.3. Multiple Redirect URIs
If multiple redirect URIs have been registered, the client MUST
include a redirect URI with the authorization request using the
"redirect_uri" request parameter.
2.3.4. Invalid Endpoint
If an authorization request fails validation due to a missing,
invalid, or mismatching redirect URI, the authorization server SHOULD
inform the resource owner of the error and MUST NOT automatically
redirect the user agent to the invalid redirect URI.
2.3.5. Endpoint Content
The redirection request to the client's endpoint typically results in
an HTML document response, processed by the user agent. If the HTML
response is served directly as the result of the redirection request,
any script included in the HTML document will execute with full
access to the redirect URI and the credentials (e.g. authorization
code) it contains. Additionally, the request URL containing the
authorization code may be sent in the HTTP Referer header to any
embedded images, stylesheets and other elements loaded in the page.
The client SHOULD NOT include any third-party scripts (e.g., third-
party analytics, social plug-ins, ad networks) in the redirection
endpoint response. Instead, it SHOULD extract the credentials from
the URI and redirect the user agent again to another endpoint without
exposing the credentials (in the URI or elsewhere). If third-party
scripts are included, the client MUST ensure that its own scripts
(used to extract and remove the credentials from the URI) will
execute first.
2.4. Client Authentication
Confidential and credentialed clients establish a client Confidential and credentialed clients establish a client
authentication method with the authorization server suitable for the authentication method with the authorization server suitable for the
security requirements of the authorization server. The authorization security requirements of the authorization server. The authorization
server MAY accept any form of client authentication meeting its server MAY accept any form of client authentication meeting its
security requirements. security requirements.
Confidential and credentialed clients are typically issued (or Confidential and credentialed clients are typically issued (or
establish) a set of client credentials used for authenticating with establish) a set of client credentials used for authenticating with
the authorization server (e.g., password, public/private key pair). the authorization server (e.g., password, public/private key pair).
Authorization servers SHOULD use client authentication if possible. The authorization server MUST authenticate the client whenever
possible. If the authorization server cannot authenticate the client
due to the client's nature, the authorization server SHOULD utilize
other means to protect resource owners from such potentially
malicious clients. For example, the authorization server can engage
the resource owner to assist in identifying the client and its
origin.
It is RECOMMENDED to use asymmetric (public-key based) methods for It is RECOMMENDED to use asymmetric (public-key based) methods for
client authentication such as mTLS [RFC8705] or "private_key_jwt" client authentication such as mTLS [RFC8705] or "private_key_jwt"
[OpenID]. When asymmetric methods for client authentication are [OpenID]. When asymmetric methods for client authentication are
used, authorization servers do not need to store sensitive symmetric used, authorization servers do not need to store sensitive symmetric
keys, making these methods more robust against a number of attacks. keys, making these methods more robust against a number of attacks.
The authorization server MAY establish a client authentication method The authorization server MAY establish a client authentication method
with public clients, which converts them to credentialed clients. with public clients, which converts them to credentialed clients.
However, the authorization server MUST NOT rely on credentialed However, the authorization server MUST NOT rely on credentialed
client authentication for the purpose of identifying the client. client authentication for the purpose of identifying the client.
The client MUST NOT use more than one authentication method in each The client MUST NOT use more than one authentication method in each
request. request.
2.3.1. Client Secret 2.4.1. Client Secret
Clients in possession of a client secret, sometimes known as a client Clients in possession of a client secret, sometimes known as a client
password, MAY use the HTTP Basic authentication scheme as defined in password, MAY use the HTTP Basic authentication scheme as defined in
[RFC2617] to authenticate with the authorization server. The client [RFC7235] to authenticate with the authorization server. The client
identifier is encoded using the "application/x-www-form-urlencoded" identifier is encoded using the "application/x-www-form-urlencoded"
encoding algorithm per Appendix B, and the encoded value is used as encoding algorithm per Appendix B, and the encoded value is used as
the username; the client secret is encoded using the same algorithm the username; the client secret is encoded using the same algorithm
and used as the password. The authorization server MUST support the and used as the password. The authorization server MUST support the
HTTP Basic authentication scheme for authenticating clients that were HTTP Basic authentication scheme for authenticating clients that were
issued a client secret. issued a client secret.
For example (with extra line breaks for display purposes only): For example (with extra line breaks for display purposes only):
Authorization: Basic czZCaGRSa3F0Mzo3RmpmcDBaQnIxS3REUmJuZlZkbUl3 Authorization: Basic czZCaGRSa3F0Mzo3RmpmcDBaQnIxS3REUmJuZlZkbUl3
Alternatively, the authorization server MAY support including the In addition to that, the authorization server MAY support including
client credentials in the request-body using the following the client credentials in the request-body using the following
parameters: parameters:
"client_id": REQUIRED. The client identifier issued to the client "client_id": REQUIRED. The client identifier issued to the client
during the registration process described by Section 2.2. during the registration process described by Section 2.2.
"client_secret": REQUIRED. The client secret. "client_secret": REQUIRED. The client secret.
Including the client credentials in the request-body using the two Including the client credentials in the request-body using the two
parameters is NOT RECOMMENDED and SHOULD be limited to clients unable parameters is NOT RECOMMENDED and SHOULD be limited to clients unable
to directly utilize the HTTP Basic authentication scheme (or other to directly utilize the HTTP Basic authentication scheme (or other
password-based HTTP authentication schemes). The parameters can only password-based HTTP authentication schemes). The parameters can only
be transmitted in the request-body and MUST NOT be included in the be transmitted in the request-body and MUST NOT be included in the
request URI. request URI.
For example, a request to refresh an access token (Section 6) using For example, a request to refresh an access token (Section 4.3) using
the body parameters (with extra line breaks for display purposes the body parameters (with extra line breaks for display purposes
only): only):
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/x-www-form-urlencoded Content-Type: application/x-www-form-urlencoded
grant_type=refresh_token&refresh_token=tGzv3JOkF0XG5Qx2TlKWIA grant_type=refresh_token&refresh_token=tGzv3JOkF0XG5Qx2TlKWIA
&client_id=s6BhdRkqt3&client_secret=7Fjfp0ZBr1KtDRbnfVdmIw &client_id=s6BhdRkqt3&client_secret=7Fjfp0ZBr1KtDRbnfVdmIw
The authorization server MUST require the use of TLS as described in The authorization server MUST require the use of TLS as described in
Section 1.6 when sending requests using password authentication. Section 1.5 when sending requests using password authentication.
Since this client authentication method involves a password, the Since this client authentication method involves a password, the
authorization server MUST protect any endpoint utilizing it against authorization server MUST protect any endpoint utilizing it against
brute force attacks. brute force attacks.
2.3.2. Other Authentication Methods 2.4.2. Other Authentication Methods
The authorization server MAY support any suitable authentication The authorization server MAY support any suitable authentication
scheme matching its security requirements. When using other scheme matching its security requirements. When using other
authentication methods, the authorization server MUST define a authentication methods, the authorization server MUST define a
mapping between the client identifier (registration record) and mapping between the client identifier (registration record) and
authentication scheme. authentication scheme.
Some additional authentication methods such as mTLS [RFC8705] and Some additional authentication methods such as mTLS [RFC8705] and
"private_key_jwt" [OpenID] are defined in the "OAuth Token Endpoint "private_key_jwt" [OpenID] are defined in the "OAuth Token Endpoint
Authentication Methods (https://www.iana.org/assignments/oauth- Authentication Methods (https://www.iana.org/assignments/oauth-
parameters/oauth-parameters.xhtml#token-endpoint-auth-method)" parameters/oauth-parameters.xhtml#token-endpoint-auth-method)"
registry, and may be useful as generic client authentication methods registry, and may be useful as generic client authentication methods
beyond the specific use of protecting the token endpoint. beyond the specific use of protecting the token endpoint.
2.4. Unregistered Clients 2.5. Unregistered Clients
This specification does not exclude the use of unregistered clients. This specification does not exclude the use of unregistered clients.
However, the use of such clients is beyond the scope of this However, the use of such clients is beyond the scope of this
specification and requires additional security analysis and review of specification and requires additional security analysis and review of
its interoperability impact. its interoperability impact.
3. Protocol Endpoints 3. Protocol Endpoints
The authorization process utilizes two authorization server endpoints The authorization process utilizes two authorization server endpoints
(HTTP resources): (HTTP resources):
* Authorization endpoint - used by the client to obtain * Authorization endpoint - used by the client to obtain
authorization from the resource owner via user-agent redirection. authorization from the resource owner via user agent redirection.
* Token endpoint - used by the client to exchange an authorization * Token endpoint - used by the client to exchange an authorization
grant for an access token, typically with client authentication. grant for an access token, typically with client authentication.
As well as one client endpoint: As well as one client endpoint:
* Redirection endpoint - used by the authorization server to return * Redirection endpoint - used by the authorization server to return
responses containing authorization credentials to the client via responses containing authorization credentials to the client via
the resource owner user-agent. the resource owner user agent.
Not every authorization grant type utilizes both endpoints. Not every authorization grant type utilizes both endpoints.
Extension grant types MAY define additional endpoints as needed. Extension grant types MAY define additional endpoints as needed.
3.1. Authorization Endpoint 3.1. Authorization Endpoint
The authorization endpoint is used to interact with the resource The authorization endpoint is used to interact with the resource
owner and obtain an authorization grant. The authorization server owner and obtain an authorization grant. The authorization server
MUST first verify the identity of the resource owner. The way in MUST first verify the identity of the resource owner. The way in
which the authorization server authenticates the resource owner which the authorization server authenticates the resource owner
skipping to change at page 19, line 27 skipping to change at page 21, line 27
or in the authorization server's metadata document ([RFC8414]). or in the authorization server's metadata document ([RFC8414]).
The endpoint URI MAY include an "application/x-www-form-urlencoded" The endpoint URI MAY include an "application/x-www-form-urlencoded"
formatted (per Appendix B) query component ([RFC3986] Section 3.4), formatted (per Appendix B) query component ([RFC3986] Section 3.4),
which MUST be retained when adding additional query parameters. The which MUST be retained when adding additional query parameters. The
endpoint URI MUST NOT include a fragment component. endpoint URI MUST NOT include a fragment component.
Since requests to the authorization endpoint result in user Since requests to the authorization endpoint result in user
authentication and the transmission of clear-text credentials (in the authentication and the transmission of clear-text credentials (in the
HTTP response), the authorization server MUST require the use of TLS HTTP response), the authorization server MUST require the use of TLS
as described in Section 1.6 when sending requests to the as described in Section 1.5 when sending requests to the
authorization endpoint. authorization endpoint.
The authorization server MUST support the use of the HTTP "GET" The authorization server MUST support the use of the HTTP "GET"
method [RFC7231] for the authorization endpoint and MAY support the method [RFC7231] for the authorization endpoint and MAY support the
use of the "POST" method as well. use of the "POST" method as well.
The authorization server MUST ignore unrecognized request parameters. The authorization server MUST ignore unrecognized request parameters.
Request and response parameters defined by this specification MUST Request and response parameters defined by this specification MUST
NOT be included more than once. Parameters sent without a value MUST NOT be included more than once. Parameters sent without a value MUST
be treated as if they were omitted from the request. be treated as if they were omitted from the request.
3.1.1. Response Type
The authorization endpoint is used by the authorization code flow.
The client informs the authorization server of the desired response
type using the following parameter:
"response_type": REQUIRED. The value MUST be "code" for requesting
an authorization code as described by Section 4.1.1, or a
registered extension value as described by Section 8.4.
Extension response types MAY contain a space-delimited (%x20) list of
values, where the order of values does not matter (e.g., response
type "a b" is the same as "b a"). The meaning of such composite
response types is defined by their respective specifications.
Some extension response types are defined by ([OpenID]).
If an authorization request is missing the "response_type" parameter,
or if the response type is not understood, the authorization server
MUST return an error response as described in Section 4.1.2.1.
3.1.2. Redirection Endpoint
After completing its interaction with the resource owner, the
authorization server directs the resource owner's user-agent back to
the client. The authorization server redirects the user-agent to one
of the client's redirection endpoints previously established with the
authorization server during the client registration process.
The redirect URI MUST be an absolute URI as defined by [RFC3986]
Section 4.3. The endpoint URI MAY include an "application/x-www-
form-urlencoded" formatted (per Appendix B) query component
([RFC3986] Section 3.4), which MUST be retained when adding
additional query parameters. The endpoint URI MUST NOT include a
fragment component.
3.1.2.1. Endpoint Request Confidentiality
The redirection endpoint SHOULD require the use of TLS as described
in Section 1.6 when the requested response type is "code", or when
the redirection request will result in the transmission of sensitive
credentials over an open network. If TLS is not available, the
authorization server SHOULD warn the resource owner about the
insecure endpoint prior to redirection (e.g., display a message
during the authorization request).
Lack of transport-layer security can have a severe impact on the
security of the client and the protected resources it is authorized
to access. The use of transport-layer security is particularly
critical when the authorization process is used as a form of
delegated end-user authentication by the client (e.g., third-party
sign-in service).
3.1.2.2. Registration Requirements
The authorization server MUST require all clients to register one or
more complete redirect URIs prior to utilizing the authorization
endpoint. The client MAY use the "state" request parameter to
achieve per-request customization if needed.
The authorization server MAY allow the client to register multiple
redirect URIs.
Without requiring registration of redirect URIs, attackers can use
the authorization endpoint as an open redirector as described in
Section 9.18.
3.1.2.3. Dynamic Configuration
If multiple redirect URIs have been registered the client MUST
include a redirect URI with the authorization request using the
"redirect_uri" request parameter.
3.1.2.4. Invalid Endpoint
If an authorization request fails validation due to a missing,
invalid, or mismatching redirect URI, the authorization server SHOULD
inform the resource owner of the error and MUST NOT automatically
redirect the user-agent to the invalid redirect URI.
3.1.2.5. Endpoint Content
The redirection request to the client's endpoint typically results in
an HTML document response, processed by the user-agent. If the HTML
response is served directly as the result of the redirection request,
any script included in the HTML document will execute with full
access to the redirect URI and the credentials (e.g. authorization
code) it contains. Additionally, the request URL containing the
authorization code may be sent in the HTTP Referer header to any
embedded images, stylesheets and other elements loaded in the page.
The client SHOULD NOT include any third-party scripts (e.g., third-
party analytics, social plug-ins, ad networks) in the redirection
endpoint response. Instead, it SHOULD extract the credentials from
the URI and redirect the user-agent again to another endpoint without
exposing the credentials (in the URI or elsewhere). If third-party
scripts are included, the client MUST ensure that its own scripts
(used to extract and remove the credentials from the URI) will
execute first.
3.2. Token Endpoint 3.2. Token Endpoint
The token endpoint is used by the client to obtain an access token The token endpoint is used by the client to obtain an access token
using a grant such as those described in Section 4 and Section 6. using a grant such as those described in Section 4 and Section 4.3.
The means through which the client obtains the location of the token The means through which the client obtains the location of the token
endpoint are beyond the scope of this specification, but the location endpoint are beyond the scope of this specification, but the location
is typically provided in the service documentation and configured is typically provided in the service documentation and configured
during development of the client, or provided in the authorization during development of the client, or provided in the authorization
server's metadata document ([RFC8414]) and fetched programmatically server's metadata document ([RFC8414]) and fetched programmatically
at runtime. at runtime.
The endpoint URI MAY include an "application/x-www-form-urlencoded" The endpoint URI MAY include an "application/x-www-form-urlencoded"
formatted (per Appendix B) query component ([RFC3986] Section 3.4) formatted (per Appendix B) query component ([RFC3986] Section 3.4)
and MUST NOT include a fragment component. and MUST NOT include a fragment component.
Since requests to the token endpoint result in the transmission of Since requests to the token endpoint result in the transmission of
clear-text credentials (in the HTTP request and response), the clear-text credentials (in the HTTP request and response), the
authorization server MUST require the use of TLS as described in authorization server MUST require the use of TLS as described in
Section 1.6 when sending requests to the token endpoint. Section 1.5 when sending requests to the token endpoint.
The client MUST use the HTTP "POST" method when making access token The client MUST use the HTTP "POST" method when making access token
requests. requests.
The authorization server MUST ignore unrecognized request parameters. The authorization server MUST ignore unrecognized request parameters.
Parameters sent without a value MUST be treated as if they were Parameters sent without a value MUST be treated as if they were
omitted from the request. Request and response parameters defined by omitted from the request. Request and response parameters defined by
this specification MUST NOT be included more than once. this specification MUST NOT be included more than once.
3.2.1. Client Authentication 3.2.1. Client Authentication
Confidential clients or other clients issued client credentials MUST Confidential or credentialed clients MUST authenticate with the
authenticate with the authorization server as described in authorization server as described in Section 2.4 when making requests
Section 2.3 when making requests to the token endpoint. Client to the token endpoint.
authentication is used for:
Client authentication is used for:
* Enforcing the binding of refresh tokens and authorization codes to * Enforcing the binding of refresh tokens and authorization codes to
the client they were issued to. Client authentication is critical the client they were issued to. Client authentication adds an
when an authorization code is transmitted to the redirection additional layer of security when an authorization code is
endpoint over an insecure channel. transmitted to the redirection endpoint over an insecure channel.
* Recovering from a compromised client by disabling the client or * Recovering from a compromised client by disabling the client or
changing its credentials, thus preventing an attacker from abusing changing its credentials, thus preventing an attacker from abusing
stolen refresh tokens. Changing a single set of client stolen refresh tokens. Changing a single set of client
credentials is significantly faster than revoking an entire set of credentials is significantly faster than revoking an entire set of
refresh tokens. refresh tokens.
* Implementing authentication management best practices, which * Implementing authentication management best practices, which
require periodic credential rotation. Rotation of an entire set require periodic credential rotation. Rotation of an entire set
of refresh tokens can be challenging, while rotation of a single of refresh tokens can be challenging, while rotation of a single
set of client credentials is significantly easier. set of client credentials is significantly easier.
3.3. Access Token Scope 3.2.2. Token Request
The client makes a request to the token endpoint by sending the
following parameters using the "application/x-www-form-urlencoded"
format per Appendix B with a character encoding of UTF-8 in the HTTP
request payload:
"client_id": REQUIRED, if the client is not authenticating with the
authorization server as described in Section 3.2.1.
"scope": OPTIONAL. The scope of the access request as described by
Section 3.2.2.1.
"grant_type": REQUIRED. Identifier of the grant type the client
uses with the particular token request. This specification
defines the values "authorization_code", "refresh_token", and
"client_credentials". The grant type determines the further
parameters required or supported by the token request. The
details of those grant types are defined below.
Confidential or credentialed clients MUST authenticate with the
authorization server as described in Section 3.2.1.
For example, the client makes the following HTTP request using TLS
(with extra line breaks for display purposes only):
POST /token HTTP/1.1
Host: server.example.com
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
Content-Type: application/x-www-form-urlencoded
grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
&code_verifier=3641a2d12d66101249cdf7a79c000c1f8c05d2aafcf14bf146497bed
The authorization server MUST:
* require client authentication for confidential and credentialed
clients (or clients with other authentication requirements),
* authenticate the client if client authentication is included
Further grant type specific processing rules apply and are specified
with the respective grant type.
3.2.2.1. Access Token Scope
The authorization and token endpoints allow the client to specify the The authorization and token endpoints allow the client to specify the
scope of the access request using the "scope" request parameter. In scope of the access request using the "scope" request parameter. In
turn, the authorization server uses the "scope" response parameter to turn, the authorization server uses the "scope" response parameter to
inform the client of the scope of the access token issued. inform the client of the scope of the access token issued.
The value of the scope parameter is expressed as a list of space- The value of the scope parameter is expressed as a list of space-
delimited, case-sensitive strings. The strings are defined by the delimited, case-sensitive strings. The strings are defined by the
authorization server. If the value contains multiple space-delimited authorization server. If the value contains multiple space-delimited
strings, their order does not matter, and each string adds an strings, their order does not matter, and each string adds an
skipping to change at page 23, line 39 skipping to change at page 24, line 27
is different from the one requested by the client, the authorization is different from the one requested by the client, the authorization
server MUST include the "scope" response parameter to inform the server MUST include the "scope" response parameter to inform the
client of the actual scope granted. client of the actual scope granted.
If the client omits the scope parameter when requesting If the client omits the scope parameter when requesting
authorization, the authorization server MUST either process the authorization, the authorization server MUST either process the
request using a pre-defined default value or fail the request request using a pre-defined default value or fail the request
indicating an invalid scope. The authorization server SHOULD indicating an invalid scope. The authorization server SHOULD
document its scope requirements and default value (if defined). document its scope requirements and default value (if defined).
4. Obtaining Authorization 3.2.3. Token Response
If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh
token.
If the request client authentication failed or is invalid, the
authorization server returns an error response as described in
Section 3.2.3.1.
The authorization server issues an access token and optional refresh
token by creating an HTTP response body using the "application/json"
media type as defined by [RFC8259] with the following parameters and
an HTTP 200 (OK) status code:
"access_token": REQUIRED. The access token issued by the
authorization server.
"token_type": REQUIRED. The type of the access token issued as
described in Section 5.1. Value is case insensitive.
"expires_in": RECOMMENDED. The lifetime in seconds of the access
token. For example, the value "3600" denotes that the access
token will expire in one hour from the time the response was
generated. If omitted, the authorization server SHOULD provide
the expiration time via other means or document the default value.
"scope": OPTIONAL, if identical to the scope requested by the
client; otherwise, REQUIRED. The scope of the access token as
described by Section 3.2.2.1.
"refresh_token": OPTIONAL. The refresh token, which can be used to
obtain new access tokens based on the grant passed in the
corresponding token request.
Authorization servers SHOULD determine, based on a risk assessment
and their own policies, whether to issue refresh tokens to a certain
client. If the authorization server decides not to issue refresh
tokens, the client MAY obtain new access tokens by starting the OAuth
flow over, for example initiating a new authorization code request.
In such a case, the authorization server may utilize cookies and
persistent grants to optimize the user experience.
If refresh tokens are issued, those refresh tokens MUST be bound to
the scope and resource servers as consented by the resource owner.
This is to prevent privilege escalation by the legitimate client and
reduce the impact of refresh token leakage.
The parameters are serialized into a JavaScript Object Notation
(JSON) structure by adding each parameter at the highest structure
level. Parameter names and string values are included as JSON
strings. Numerical values are included as JSON numbers. The order
of parameters does not matter and can vary.
The authorization server MUST include the HTTP "Cache-Control"
response header field [RFC7234] with a value of "no-store" in any
response containing tokens, credentials, or other sensitive
information.
For example:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"access_token":"2YotnFZFEjr1zCsicMWpAA",
"token_type":"Bearer",
"expires_in":3600,
"refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA",
"example_parameter":"example_value"
}
The client MUST ignore unrecognized value names in the response. The
sizes of tokens and other values received from the authorization
server are left undefined. The client should avoid making
assumptions about value sizes. The authorization server SHOULD
document the size of any value it issues.
3.2.3.1. Error Response
The authorization server responds with an HTTP 400 (Bad Request)
status code (unless specified otherwise) and includes the following
parameters with the response:
"error": REQUIRED. A single ASCII [USASCII] error code from the
following:
"invalid_request": The request is missing a required parameter,
includes an unsupported parameter value (other than grant
type), repeats a parameter, includes multiple credentials,
utilizes more than one mechanism for authenticating the client,
contains a "code_verifier" although no "code_challenge" was
sent in the authorization request, or is otherwise malformed.
"invalid_client": Client authentication failed (e.g., unknown
client, no client authentication included, or unsupported
authentication method). The authorization server MAY return an
HTTP 401 (Unauthorized) status code to indicate which HTTP
authentication schemes are supported. If the client attempted
to authenticate via the "Authorization" request header field,
the authorization server MUST respond with an HTTP 401
(Unauthorized) status code and include the "WWW-Authenticate"
response header field matching the authentication scheme used
by the client.
"invalid_grant": The provided authorization grant (e.g.,
authorization code, resource owner credentials) or refresh
token is invalid, expired, revoked, does not match the redirect
URI used in the authorization request, or was issued to another
client.
"unauthorized_client": The authenticated client is not authorized
to use this authorization grant type.
"unsupported_grant_type": The authorization grant type is not
supported by the authorization server.
"invalid_scope": The requested scope is invalid, unknown,
malformed, or exceeds the scope granted by the resource owner.
Values for the "error" parameter MUST NOT include characters
outside the set %x20-21 / %x23-5B / %x5D-7E.
"error_description": OPTIONAL. Human-readable ASCII [USASCII] text
providing additional information, used to assist the client
developer in understanding the error that occurred. Values for
the "error_description" parameter MUST NOT include characters
outside the set %x20-21 / %x23-5B / %x5D-7E.
"error_uri": OPTIONAL. A URI identifying a human-readable web page
with information about the error, used to provide the client
developer with additional information about the error. Values for
the "error_uri" parameter MUST conform to the URI-reference syntax
and thus MUST NOT include characters outside the set %x21 /
%x23-5B / %x5D-7E.
The parameters are included in the payload of the HTTP response using
the "application/json" media type as defined by [RFC7159]. The
parameters are serialized into a JSON structure by adding each
parameter at the highest structure level. Parameter names and string
values are included as JSON strings. Numerical values are included
as JSON numbers. The order of parameters does not matter and can
vary.
For example:
HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store
{
"error":"invalid_request"
}
4. Grant Types
To request an access token, the client obtains authorization from the To request an access token, the client obtains authorization from the
resource owner. OAuth defines two authorization grant types: resource owner. This specification defines the following
authorization code and client credentials. It also provides an authorization grant types:
extension mechanism for defining additional grant types.
* authorization code
* client credentials, and
* refresh token
It also provides an extension mechanism for defining additional grant
types.
4.1. Authorization Code Grant 4.1. Authorization Code Grant
The authorization code grant type is used to obtain both access The authorization code grant type is used to obtain both access
tokens and refresh tokens. tokens and refresh tokens.
The grant type uses the additional authorization endpoint to let the
authorization server interact with the resource owner in order to get
consent for resource access.
Since this is a redirect-based flow, the client must be capable of Since this is a redirect-based flow, the client must be capable of
initiating the flow with the resource owner's user-agent (typically a initiating the flow with the resource owner's user agent (typically a
web browser) and capable of being redirected back to from the web browser) and capable of being redirected back to from the
authorization server. authorization server.
+----------+ +----------+
| Resource | | Resource |
| Owner | | Owner |
| | | |
+----------+ +----------+
^ ^
| |
skipping to change at page 24, line 37 skipping to change at page 28, line 46
| | | | | | | |
^ v | | ^ v | |
+---------+ | | +---------+ | |
| |>---(4)-- Authorization Code ---------' | | |>---(4)-- Authorization Code ---------' |
| Client | & Redirect URI | | Client | & Redirect URI |
| | | | | |
| |<---(5)----- Access Token -------------------' | |<---(5)----- Access Token -------------------'
+---------+ (w/ Optional Refresh Token) +---------+ (w/ Optional Refresh Token)
Note: The lines illustrating steps (1), (2), and (3) are broken into Note: The lines illustrating steps (1), (2), and (3) are broken into
two parts as they pass through the user-agent. two parts as they pass through the user agent.
Figure 3: Authorization Code Flow Figure 3: Authorization Code Flow
The flow illustrated in Figure 3 includes the following steps: The flow illustrated in Figure 3 includes the following steps:
(1) The client initiates the flow by directing the resource owner's (1) The client initiates the flow by directing the resource owner's
user-agent to the authorization endpoint. The client includes its user agent to the authorization endpoint. The client includes its
client identifier, code challenge (derived from a generated code client identifier, code challenge (derived from a generated code
verifier), optional requested scope, optional local state, and a verifier), optional requested scope, optional local state, and a
redirect URI to which the authorization server will send the user- redirect URI to which the authorization server will send the user
agent back once access is granted (or denied). agent back once access is granted (or denied).
(2) The authorization server authenticates the resource owner (via (2) The authorization server authenticates the resource owner (via
the user-agent) and establishes whether the resource owner grants or the user agent) and establishes whether the resource owner grants or
denies the client's access request. denies the client's access request.
(3) Assuming the resource owner grants access, the authorization (3) Assuming the resource owner grants access, the authorization
server redirects the user-agent back to the client using the redirect server redirects the user agent back to the client using the redirect
URI provided earlier (in the request or during client registration). URI provided earlier (in the request or during client registration).
The redirect URI includes an authorization code and any local state The redirect URI includes an authorization code and any local state
provided by the client earlier. provided by the client earlier.
(4) The client requests an access token from the authorization (4) The client requests an access token from the authorization
server's token endpoint by including the authorization code received server's token endpoint by including the authorization code received
in the previous step, and including its code verifier. When making in the previous step, and including its code verifier. When making
the request, the client authenticates with the authorization server the request, the client authenticates with the authorization server
if it can. The client includes the redirect URI used to obtain the if it can. The client includes the redirect URI used to obtain the
authorization code for verification. authorization code for verification.
skipping to change at page 25, line 29 skipping to change at page 29, line 40
validates the authorization code, validates the code verifier, and validates the authorization code, validates the code verifier, and
ensures that the redirect URI received matches the URI used to ensures that the redirect URI received matches the URI used to
redirect the client in step (3). If valid, the authorization server redirect the client in step (3). If valid, the authorization server
responds back with an access token and, optionally, a refresh token. responds back with an access token and, optionally, a refresh token.
4.1.1. Authorization Request 4.1.1. Authorization Request
To begin the authorization request, the client builds the To begin the authorization request, the client builds the
authorization request URI by adding parameters to the authorization authorization request URI by adding parameters to the authorization
server's authorization endpoint URI. The client will eventually server's authorization endpoint URI. The client will eventually
redirect the user-agent to this URI to initiate the request, as redirect the user agent to this URI to initiate the request.
described in Section 4.1.1.1.
Clients use a unique secret per authorization request to protect Clients use a unique secret per authorization request to protect
against authorization code injection and CSRF attacks. The client against authorization code injection and CSRF attacks. The client
first generates this secret, which it can use at the time of first generates this secret, which it can use at the time of
redeeming the authorization code to prove that the client using the redeeming the authorization code to prove that the client using the
authorization code is the same client that requested it. authorization code is the same client that requested it.
4.1.1.1. Client Initiates the Authorization Request
The client constructs the request URI by adding the following The client constructs the request URI by adding the following
parameters to the query component of the authorization endpoint URI parameters to the query component of the authorization endpoint URI
using the "application/x-www-form-urlencoded" format, per Appendix B: using the "application/x-www-form-urlencoded" format, per Appendix B:
"response_type": REQUIRED. Value MUST be set to "code". "response_type": REQUIRED. The authorization endpoint supports
different sets of request and response pameters. The client
determines the type of flow by using a certain "response_type"
value. This specification defines the value "code", which must be
used to signal that the client wants to use the authorization code
flow.
Extension response types MAY contain a space-delimited (%x20) list of
values, where the order of values does not matter (e.g., response
type "a b" is the same as "b a"). The meaning of such composite
response types is defined by their respective specifications.
Some extension response types are defined by ([OpenID]).
If an authorization request is missing the "response_type" parameter,
or if the response type is not understood, the authorization server
MUST return an error response as described in Section 4.1.2.1.
"client_id": REQUIRED. The client identifier as described in "client_id": REQUIRED. The client identifier as described in
Section 2.2. Section 2.2.
"code_challenge": REQUIRED or RECOMMENDED (see Section 9.8). Code "code_challenge": REQUIRED or RECOMMENDED (see Section 7.8). Code
challenge. challenge.
"code_challenge_method": OPTIONAL, defaults to "plain" if not "code_challenge_method": OPTIONAL, defaults to "plain" if not
present in the request. Code verifier transformation method is present in the request. Code verifier transformation method is
"S256" or "plain". "S256" or "plain".
"redirect_uri": OPTIONAL. As described in Section 3.1.2. "redirect_uri": OPTIONAL. As described in Section 2.3.
"scope": OPTIONAL. The scope of the access request as described by "scope": OPTIONAL. The scope of the access request as described by
Section 3.3. Section 3.2.2.1.
"state": OPTIONAL. An opaque value used by the client to maintain "state": OPTIONAL. An opaque value used by the client to maintain
state between the request and callback. The authorization server state between the request and callback. The authorization server
includes this value when redirecting the user-agent back to the includes this value when redirecting the user agent back to the
client. client.
The "code_verifier" is a unique high-entropy cryptographically random The "code_verifier" is a unique high-entropy cryptographically random
string generated for each authorization request, using the unreserved string generated for each authorization request, using the unreserved
characters "[A-Z] / [a-z] / [0-9] / "-" / "." / "_" / "~"", with a characters "[A-Z] / [a-z] / [0-9] / "-" / "." / "_" / "~"", with a
minimum length of 43 characters and a maximum length of 128 minimum length of 43 characters and a maximum length of 128
characters. characters.
The client stores the "code_verifier" temporarily, and calculates the The client stores the "code_verifier" temporarily, and calculates the
"code_challenge" which it uses in the authorization request. "code_challenge" which it uses in the authorization request.
skipping to change at page 27, line 22 skipping to change at page 31, line 47
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
ALPHA = %x41-5A / %x61-7A ALPHA = %x41-5A / %x61-7A
DIGIT = %x30-39 DIGIT = %x30-39
The properties "code_challenge" and "code_verifier" are adopted from The properties "code_challenge" and "code_verifier" are adopted from
the OAuth 2.0 extension known as "Proof-Key for Code Exchange", or the OAuth 2.0 extension known as "Proof-Key for Code Exchange", or
PKCE ([RFC7636]) where this technique was originally developed. PKCE ([RFC7636]) where this technique was originally developed.
Clients MUST use "code_challenge" and "code_verifier" and Clients MUST use "code_challenge" and "code_verifier" and
authorization servers MUST enforce their use except under the authorization servers MUST enforce their use except under the
conditions described in Section 9.8. In this case, using and conditions described in Section 7.8. In this case, using and
enforcing "code_challenge" and "code_verifier" as described in the enforcing "code_challenge" and "code_verifier" as described in the
following is still RECOMMENDED. following is still RECOMMENDED.
The client directs the resource owner to the constructed URI using an The client directs the resource owner to the constructed URI using an
HTTP redirection, or by other means available to it via the user- HTTP redirection, or by other means available to it via the user
agent. agent.
For example, the client directs the user-agent to make the following For example, the client directs the user agent to make the following
HTTP request using TLS (with extra line breaks for display purposes HTTP request using TLS (with extra line breaks for display purposes
only): only):
GET /authorize?response_type=code&client_id=s6BhdRkqt3&state=xyz GET /authorize?response_type=code&client_id=s6BhdRkqt3&state=xyz
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
&code_challenge=6fdkQaPm51l13DSukcAH3Mdx7_ntecHYd1vi3n0hMZY &code_challenge=6fdkQaPm51l13DSukcAH3Mdx7_ntecHYd1vi3n0hMZY
&code_challenge_method=S256 HTTP/1.1 &code_challenge_method=S256 HTTP/1.1
Host: server.example.com Host: server.example.com
The authorization server validates the request to ensure that all The authorization server validates the request to ensure that all
skipping to change at page 28, line 10 skipping to change at page 32, line 34
one of the registered redirect URIs previously established during one of the registered redirect URIs previously established during
client registration (Section 2). When comparing the two URIs the client registration (Section 2). When comparing the two URIs the
authorization server MUST using simple character-by-character string authorization server MUST using simple character-by-character string
comparison as defined in [RFC3986], Section 6.2.1. comparison as defined in [RFC3986], Section 6.2.1.
If the request is valid, the authorization server authenticates the If the request is valid, the authorization server authenticates the
resource owner and obtains an authorization decision (by asking the resource owner and obtains an authorization decision (by asking the
resource owner or by establishing approval via other means). resource owner or by establishing approval via other means).
When a decision is established, the authorization server directs the When a decision is established, the authorization server directs the
user-agent to the provided client redirect URI using an HTTP user agent to the provided client redirect URI using an HTTP
redirection response, or by other means available to it via the user- redirection response, or by other means available to it via the user
agent. agent.
4.1.2. Authorization Response 4.1.2. Authorization Response
If the resource owner grants the access request, the authorization If the resource owner grants the access request, the authorization
server issues an authorization code and delivers it to the client by server issues an authorization code and delivers it to the client by
adding the following parameters to the query component of the adding the following parameters to the query component of the
redirect URI using the "application/x-www-form-urlencoded" format, redirect URI using the "application/x-www-form-urlencoded" format,
per Appendix B: per Appendix B:
skipping to change at page 28, line 36 skipping to change at page 33, line 11
client MUST NOT use the authorization code more than once. If an client MUST NOT use the authorization code more than once. If an
authorization code is used more than once, the authorization authorization code is used more than once, the authorization
server MUST deny the request and SHOULD revoke (when possible) all server MUST deny the request and SHOULD revoke (when possible) all
access tokens and refresh tokens previously issued based on that access tokens and refresh tokens previously issued based on that
authorization code. The authorization code is bound to the client authorization code. The authorization code is bound to the client
identifier and redirect URI. identifier and redirect URI.
"state": REQUIRED if the "state" parameter was present in the client "state": REQUIRED if the "state" parameter was present in the client
authorization request. The exact value received from the client. authorization request. The exact value received from the client.
For example, the authorization server redirects the user-agent by For example, the authorization server redirects the user agent by
sending the following HTTP response: sending the following HTTP response:
HTTP/1.1 302 Found HTTP/1.1 302 Found
Location: https://client.example.com/cb?code=SplxlOBeZQQYbYS6WxSbIA Location: https://client.example.com/cb?code=SplxlOBeZQQYbYS6WxSbIA
&state=xyz &state=xyz
The client MUST ignore unrecognized response parameters. The The client MUST ignore unrecognized response parameters. The
authorization code string size is left undefined by this authorization code string size is left undefined by this
specification. The client should avoid making assumptions about code specification. The client should avoid making assumptions about code
value sizes. The authorization server SHOULD document the size of value sizes. The authorization server SHOULD document the size of
skipping to change at page 29, line 19 skipping to change at page 33, line 42
"code_challenge_method" values may be stored in encrypted form in the "code_challenge_method" values may be stored in encrypted form in the
code itself, but the server MUST NOT include the "code_challenge" code itself, but the server MUST NOT include the "code_challenge"
value in a response parameter in a form that entities other than the value in a response parameter in a form that entities other than the
AS can extract. AS can extract.
4.1.2.1. Error Response 4.1.2.1. Error Response
If the request fails due to a missing, invalid, or mismatching If the request fails due to a missing, invalid, or mismatching
redirect URI, or if the client identifier is missing or invalid, the redirect URI, or if the client identifier is missing or invalid, the
authorization server SHOULD inform the resource owner of the error authorization server SHOULD inform the resource owner of the error
and MUST NOT automatically redirect the user-agent to the invalid and MUST NOT automatically redirect the user agent to the invalid
redirect URI. redirect URI.
An AS MUST reject requests without a "code_challenge" from public An AS MUST reject requests without a "code_challenge" from public
clients, and MUST reject such requests from other clients unless clients, and MUST reject such requests from other clients unless
there is reasonable assurance that the client mitigates authorization there is reasonable assurance that the client mitigates authorization
code injection in other ways. See Section 9.8 for details. code injection in other ways. See Section 7.8 for details.
If the server does not support the requested "code_challenge_method" If the server does not support the requested "code_challenge_method"
transformation, the authorization endpoint MUST return the transformation, the authorization endpoint MUST return the
authorization error response with "error" value set to authorization error response with "error" value set to
"invalid_request". The "error_description" or the response of "invalid_request". The "error_description" or the response of
"error_uri" SHOULD explain the nature of error, e.g., transform "error_uri" SHOULD explain the nature of error, e.g., transform
algorithm not supported. algorithm not supported.
If the resource owner denies the access request or if the request If the resource owner denies the access request or if the request
fails for reasons other than a missing or invalid redirect URI, the fails for reasons other than a missing or invalid redirect URI, the
skipping to change at page 30, line 42 skipping to change at page 35, line 19
"error_uri": OPTIONAL. A URI identifying a human-readable web page "error_uri": OPTIONAL. A URI identifying a human-readable web page
with information about the error, used to provide the client with information about the error, used to provide the client
developer with additional information about the error. Values for developer with additional information about the error. Values for
the "error_uri" parameter MUST conform to the URI-reference syntax the "error_uri" parameter MUST conform to the URI-reference syntax
and thus MUST NOT include characters outside the set %x21 / and thus MUST NOT include characters outside the set %x21 /
%x23-5B / %x5D-7E. %x23-5B / %x5D-7E.
"state": REQUIRED if a "state" parameter was present in the client "state": REQUIRED if a "state" parameter was present in the client
authorization request. The exact value received from the client. authorization request. The exact value received from the client.
For example, the authorization server redirects the user-agent by For example, the authorization server redirects the user agent by
sending the following HTTP response: sending the following HTTP response:
HTTP/1.1 302 Found HTTP/1.1 302 Found
Location: https://client.example.com/cb?error=access_denied&state=xyz Location: https://client.example.com/cb?error=access_denied&state=xyz
4.1.3. Access Token Request 4.1.3. Token Endpoint Extension
The client makes a request to the token endpoint by sending the The authorization grant type is identified at the token endpoint with
following parameters using the "application/x-www-form-urlencoded" the "grant_type" value of "authorization_code".
format per Appendix B with a character encoding of UTF-8 in the HTTP
request payload:
"grant_type": REQUIRED. Value MUST be set to "authorization_code". If this value is set, the following additional token request
parameters beyond Section 3.2.2 are required:
"code": REQUIRED. The authorization code received from the "code": REQUIRED. The authorization code received from the
authorization server. authorization server.
"redirect_uri": REQUIRED, if the "redirect_uri" parameter was "redirect_uri": REQUIRED, if the "redirect_uri" parameter was
included in the authorization request as described in included in the authorization request as described in
Section 4.1.1, and their values MUST be identical. Section 4.1.1, and their values MUST be identical.
"client_id": REQUIRED, if the client is not authenticating with the
authorization server as described in Section 3.2.1.
"code_verifier": REQUIRED, if the "code_challenge" parameter was "code_verifier": REQUIRED, if the "code_challenge" parameter was
included in the authorization request. MUST NOT be used included in the authorization request. MUST NOT be used
otherwise. The original code verifier string. otherwise. The original code verifier string.
Confidential or credentialed clients MUST authenticate with the
authorization server as described in Section 3.2.1.
For example, the client makes the following HTTP request using TLS For example, the client makes the following HTTP request using TLS
(with extra line breaks for display purposes only): (with extra line breaks for display purposes only):
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
Content-Type: application/x-www-form-urlencoded Content-Type: application/x-www-form-urlencoded
grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
&code_verifier=3641a2d12d66101249cdf7a79c000c1f8c05d2aafcf14bf146497bed &code_verifier=3641a2d12d66101249cdf7a79c000c1f8c05d2aafcf14bf146497bed
The authorization server MUST: In addition to the processing rules in Section 3.2.2, the
authorization server MUST:
* require client authentication for confidential and credentialed
clients (or clients with other authentication requirements),
* authenticate the client if client authentication is included,
* ensure that the authorization code was issued to the authenticated * ensure that the authorization code was issued to the authenticated
confidential or credentialed client, or if the client is public, confidential or credentialed client, or if the client is public,
ensure that the code was issued to "client_id" in the request, ensure that the code was issued to "client_id" in the request,
* verify that the authorization code is valid, * verify that the authorization code is valid,
* verify that the "code_verifier" parameter is present if and only * verify that the "code_verifier" parameter is present if and only
if a "code_challenge" parameter was present in the authorization if a "code_challenge" parameter was present in the authorization
request, request,
* if a "code_verifier" is present, verify the "code_verifier" by * if a "code_verifier" is present, verify the "code_verifier" by
calculating the code challenge from the received "code_verifier" calculating the code challenge from the received "code_verifier"
and comparing it with the previously associated "code_challenge", and comparing it with the previously associated "code_challenge",
after first transforming it according to the after first transforming it according to the
"code_challenge_method" method specified by the client, and "code_challenge_method" method specified by the client, and
* ensure that the "redirect_uri" parameter is present if the * ensure that the "redirect_uri" parameter is present if the
"redirect_uri" parameter was included in the initial authorization "redirect_uri" parameter was included in the initial authorization
request as described in Section 4.1.1.1, and if included ensure request as described in Section 4.1.1, and if included ensure that
that their values are identical. their values are identical.
4.1.4. Access Token Response
If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh
token as described in Section 5.1. If the request client
authentication failed or is invalid, the authorization server returns
an error response as described in Section 5.2.
An example successful response:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
Pragma: no-cache
{
"access_token": "2YotnFZFEjr1zCsicMWpAA",
"token_type": "Bearer",
"expires_in": 3600,
"refresh_token": "tGzv3JOkF0XG5Qx2TlKWIA",
"example_parameter": "example_value"
}
4.2. Client Credentials Grant 4.2. Client Credentials Grant
The client can request an access token using only its client The client can request an access token using only its client
credentials (or other supported means of authentication) when the credentials (or other supported means of authentication) when the
client is requesting access to the protected resources under its client is requesting access to the protected resources under its
control, or those of another resource owner that have been previously control, or those of another resource owner that have been previously
arranged with the authorization server (the method of which is beyond arranged with the authorization server (the method of which is beyond
the scope of this specification). the scope of this specification).
skipping to change at page 33, line 16 skipping to change at page 37, line 13
or credentialed clients. or credentialed clients.
+---------+ +---------------+ +---------+ +---------------+
| | | | | | | |
| |>--(1)- Client Authentication --->| Authorization | | |>--(1)- Client Authentication --->| Authorization |
| Client | | Server | | Client | | Server |
| |<--(2)---- Access Token ---------<| | | |<--(2)---- Access Token ---------<| |
| | | | | | | |
+---------+ +---------------+ +---------+ +---------------+
Figure 4: Client Credentials Flow Figure 4: Client Credentials Grant
The flow illustrated in Figure 4 includes the following steps: The use of the client credentials grant illustrated in Figure 4
includes the following steps:
(1) The client authenticates with the authorization server and (1) The client authenticates with the authorization server and
requests an access token from the token endpoint. requests an access token from the token endpoint.
(2) The authorization server authenticates the client, and if valid, (2) The authorization server authenticates the client, and if valid,
issues an access token. issues an access token.
4.2.1. Authorization Request and Response 4.2.1. Token Endpoint Extension
Since the client authentication is used as the authorization grant,
no additional authorization request is needed.
4.2.2. Access Token Request
The client makes a request to the token endpoint by adding the
following parameters using the "application/x-www-form-urlencoded"
format per Appendix B with a character encoding of UTF-8 in the HTTP
request payload:
"grant_type": REQUIRED. Value MUST be set to "client_credentials".
"scope": OPTIONAL. The scope of the access request as described by The authorization grant type is identified at the token endpoint with
Section 3.3. the "grant_type" value of "client_credentials".
The client MUST authenticate with the authorization server as If this value is set, no additional parameters beyond Section 3.2.2
described in Section 3.2.1. are required/supported:
For example, the client makes the following HTTP request using For example, the client makes the following HTTP request using
transport-layer security (with extra line breaks for display purposes transport-layer security (with extra line breaks for display purposes
only): only):
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
Content-Type: application/x-www-form-urlencoded Content-Type: application/x-www-form-urlencoded
grant_type=client_credentials grant_type=client_credentials
The authorization server MUST authenticate the client. The authorization server MUST authenticate the client.
4.2.3. Access Token Response 4.3. Refresh Token Grant
If the access token request is valid and authorized, the
authorization server issues an access token as described in
Section 5.1. A refresh token SHOULD NOT be included. If the request
failed client authentication or is invalid, the authorization server
returns an error response as described in Section 5.2.
An example successful response:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
Pragma: no-cache
{
"access_token": "2YotnFZFEjr1zCsicMWpAA",
"token_type": "Bearer",
"expires_in": 3600,
"example_parameter": "example_value"
}
4.3. Extension Grants
The client uses an extension grant type by specifying the grant type
using an absolute URI (defined by the authorization server) as the
value of the "grant_type" parameter of the token endpoint, and by
adding any additional parameters necessary.
For example, to request an access token using the Device
Authorization Grant as defined by [RFC8628] after the user has
authorized the client on a separate device, the client makes the
following HTTP request using TLS (with extra line breaks for display
purposes only):
POST /token HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded
grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Adevice_code
&device_code=GmRhmhcxhwEzkoEqiMEg_DnyEysNkuNhszIySk9eS
&client_id=C409020731
If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh
token as described in Section 5.1. If the request failed client
authentication or is invalid, the authorization server returns an
error response as described in Section 5.2.
5. Issuing an Access Token
If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh
token as described in Section 5.1. If the request failed client
authentication or is invalid, the authorization server returns an
error response as described in Section 5.2.
5.1. Successful Response
The authorization server issues an access token and optional refresh
token by creating an HTTP response body using the "application/json"
media type as defined by [RFC8259] with the following parameters and
an HTTP 200 (OK) status code:
"access_token": REQUIRED. The access token issued by the
authorization server.
"token_type": REQUIRED. The type of the access token issued as
described in Section 7.1. Value is case insensitive.
"expires_in": RECOMMENDED. The lifetime in seconds of the access
token. For example, the value "3600" denotes that the access
token will expire in one hour from the time the response was
generated. If omitted, the authorization server SHOULD provide
the expiration time via other means or document the default value.
"refresh_token": OPTIONAL. The refresh token, which can be used to
obtain new access tokens using the same authorization grant as
described in Section 6.
"scope": OPTIONAL, if identical to the scope requested by the
client; otherwise, REQUIRED. The scope of the access token as
described by Section 3.3.
The parameters are serialized into a JavaScript Object Notation
(JSON) structure by adding each parameter at the highest structure
level. Parameter names and string values are included as JSON
strings. Numerical values are included as JSON numbers. The order
of parameters does not matter and can vary.
The authorization server MUST include the HTTP "Cache-Control"
response header field [RFC7234] with a value of "no-store" in any
response containing tokens, credentials, or other sensitive
information, as well as the "Pragma" response header field [RFC7234]
with a value of "no-cache".
For example:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
Pragma: no-cache
{
"access_token":"2YotnFZFEjr1zCsicMWpAA",
"token_type":"Bearer",
"expires_in":3600,
"refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA",
"example_parameter":"example_value"
}
The client MUST ignore unrecognized value names in the response. The
sizes of tokens and other values received from the authorization
server are left undefined. The client should avoid making
assumptions about value sizes. The authorization server SHOULD
document the size of any value it issues.
5.2. Error Response
The authorization server responds with an HTTP 400 (Bad Request)
status code (unless specified otherwise) and includes the following
parameters with the response:
"error": REQUIRED. A single ASCII [USASCII] error code from the
following:
"invalid_request": The request is missing a required parameter,
includes an unsupported parameter value (other than grant
type), repeats a parameter, includes multiple credentials,
utilizes more than one mechanism for authenticating the client,
contains a "code_verifier" although no "code_challenge" was
sent in the authorization request, or is otherwise malformed.
"invalid_client": Client authentication failed (e.g., unknown
client, no client authentication included, or unsupported
authentication method). The authorization server MAY return an
HTTP 401 (Unauthorized) status code to indicate which HTTP
authentication schemes are supported. If the client attempted
to authenticate via the "Authorization" request header field,
the authorization server MUST respond with an HTTP 401
(Unauthorized) status code and include the "WWW-Authenticate"
response header field matching the authentication scheme used
by the client.
"invalid_grant": The provided authorization grant (e.g.,
authorization code, resource owner credentials) or refresh
token is invalid, expired, revoked, does not match the redirect
URI used in the authorization request, or was issued to another
client.
"unauthorized_client": The authenticated client is not authorized
to use this authorization grant type.
"unsupported_grant_type": The authorization grant type is not
supported by the authorization server.
"invalid_scope": The requested scope is invalid, unknown,
malformed, or exceeds the scope granted by the resource owner.
Values for the "error" parameter MUST NOT include characters
outside the set %x20-21 / %x23-5B / %x5D-7E.
"error_description": OPTIONAL. Human-readable ASCII [USASCII] text
providing additional information, used to assist the client
developer in understanding the error that occurred. Values for
the "error_description" parameter MUST NOT include characters
outside the set %x20-21 / %x23-5B / %x5D-7E.
"error_uri": OPTIONAL. A URI identifying a human-readable web page
with information about the error, used to provide the client
developer with additional information about the error. Values for
the "error_uri" parameter MUST conform to the URI-reference syntax
and thus MUST NOT include characters outside the set %x21 /
%x23-5B / %x5D-7E.
The parameters are included in the payload of the HTTP response using
the "application/json" media type as defined by [RFC7159]. The
parameters are serialized into a JSON structure by adding each
parameter at the highest structure level. Parameter names and string
values are included as JSON strings. Numerical values are included
as JSON numbers. The order of parameters does not matter and can
vary.
For example:
HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store
Pragma: no-cache
{
"error":"invalid_request"
}
6. Refreshing an Access Token
Authorization servers SHOULD determine, based on a risk assessment
and their own policies, whether to issue refresh tokens to a certain
client. If the authorization server decides not to issue refresh
tokens, the client MAY obtain new access tokens by starting the OAuth
flow over, for example initiating a new authorization code request.
In such a case, the authorization server may utilize cookies and
persistent grants to optimize the user experience.
If refresh tokens are issued, those refresh tokens MUST be bound to The refresh token is a credential issued by the authorization server
the scope and resource servers as consented by the resource owner. to a client, which can be used to obtain new (fresh) access tokens
This is to prevent privilege escalation by the legitimate client and based on an existing grant. The client uses this option either
reduce the impact of refresh token leakage. because the previous access token has expired or the client
previously obtained an access token with a scope more narrow than
approved by the respective grant and later requires an access token
with a different scope under the same grant.
6.1. Refresh Token Request 4.3.1. Token Endpoint Extension
To use a refresh token to obtain a new access token, the client makes The authorization grant type is identified at the token endpoint with
a request to the token endpoint by adding the following parameters the "grant_type" value of "refresh_token".
using the "application/x-www-form-urlencoded" format (per Appendix B)
with a character encoding of UTF-8 in the HTTP request payload:
"grant_type": REQUIRED. Value MUST be set to "refresh_token". If this value is set, the following additional parameters beyond
Section 3.2.2 are required/supported:
"refresh_token": REQUIRED. The refresh token issued to the client. "refresh_token": REQUIRED. The refresh token issued to the client.
"scope": OPTIONAL. The scope of the access request as described by
Section 3.3. The requested scope MUST NOT include any scope not
originally granted by the resource owner, and if omitted is
treated as equal to the scope originally granted by the resource
owner.
Because refresh tokens are typically long-lasting credentials used to Because refresh tokens are typically long-lasting credentials used to
request additional access tokens, the refresh token is bound to the request additional access tokens, the refresh token is bound to the
client to which it was issued. Confidential or credentialed clients client to which it was issued. Confidential or credentialed clients
MUST authenticate with the authorization server as described in MUST authenticate with the authorization server as described in
Section 3.2.1. Section 3.2.1.
For example, the client makes the following HTTP request using For example, the client makes the following HTTP request using
transport-layer security (with extra line breaks for display purposes transport-layer security (with extra line breaks for display purposes
only): only):
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
Content-Type: application/x-www-form-urlencoded Content-Type: application/x-www-form-urlencoded
grant_type=refresh_token&refresh_token=tGzv3JOkF0XG5Qx2TlKWIA grant_type=refresh_token&refresh_token=tGzv3JOkF0XG5Qx2TlKWIA
The authorization server MUST: In addition to the processing rules in Section 3.2.2, the
authorization server MUST:
* require client authentication for confidential or credentialed
clients
* authenticate the client if client authentication is included and
ensure that the refresh token was issued to the authenticated
client, and
* validate the refresh token. * validate the refresh token.
Authorization servers SHOULD utilize one of these methods to detect Authorization servers SHOULD utilize one of these methods to detect
refresh token replay by malicious actors for public clients: refresh token replay by malicious actors for public clients:
* _Sender-constrained refresh tokens:_ the authorization server * _Sender-constrained refresh tokens:_ the authorization server
cryptographically binds the refresh token to a certain client cryptographically binds the refresh token to a certain client
instance by utilizing [I-D.ietf-oauth-token-binding], [RFC8705], instance by utilizing [I-D.ietf-oauth-token-binding], [RFC8705],
[I-D.ietf-oauth-dpop], or another suitable method. [I-D.ietf-oauth-dpop], or another suitable method.
skipping to change at page 40, line 17 skipping to change at page 39, line 30
cost of forcing the legitimate client to obtain a fresh cost of forcing the legitimate client to obtain a fresh
authorization grant. authorization grant.
Implementation note: the grant to which a refresh token belongs may Implementation note: the grant to which a refresh token belongs may
be encoded into the refresh token itself. This can enable an be encoded into the refresh token itself. This can enable an
authorization server to efficiently determine the grant to which a authorization server to efficiently determine the grant to which a
refresh token belongs, and by extension, all refresh tokens that need refresh token belongs, and by extension, all refresh tokens that need
to be revoked. Authorization servers MUST ensure the integrity of to be revoked. Authorization servers MUST ensure the integrity of
the refresh token value in this case, for example, using signatures. the refresh token value in this case, for example, using signatures.
6.2. Refresh Token Response 4.3.2. Refresh Token Response
If valid and authorized, the authorization server issues an access If valid and authorized, the authorization server issues an access
token as described in Section 5.1. If the request failed token as described in Section 3.2.3.
verification or is invalid, the authorization server returns an error
response as described in Section 5.2.
The authorization server MAY issue a new refresh token, in which case The authorization server MAY issue a new refresh token, in which case
the client MUST discard the old refresh token and replace it with the the client MUST discard the old refresh token and replace it with the
new refresh token. The authorization server MAY revoke the old new refresh token.
refresh token after issuing a new refresh token to the client. If a
new refresh token is issued, the refresh token scope MUST be The authorization server MAY revoke the old refresh token after
identical to that of the refresh token included by the client in the issuing a new refresh token to the client. If a new refresh token is
request. issued, the refresh token scope MUST be identical to that of the
refresh token included by the client in the request.
Authorization servers MAY revoke refresh tokens automatically in case Authorization servers MAY revoke refresh tokens automatically in case
of a security event, such as: of a security event, such as:
* password change * password change
* logout at the authorization server * logout at the authorization server
Refresh tokens SHOULD expire if the client has been inactive for some Refresh tokens SHOULD expire if the client has been inactive for some
time, i.e., the refresh token has not been used to obtain new access time, i.e., the refresh token has not been used to obtain new access
tokens for some time. The expiration time is at the discretion of tokens for some time. The expiration time is at the discretion of
the authorization server. It might be a global value or determined the authorization server. It might be a global value or determined
based on the client policy or the grant associated with the refresh based on the client policy or the grant associated with the refresh
token (and its sensitivity). token (and its sensitivity).
7. Accessing Protected Resources 4.4. Extension Grants
The client uses an extension grant type by specifying the grant type
using an absolute URI (defined by the authorization server) as the
value of the "grant_type" parameter of the token endpoint, and by
adding any additional parameters necessary.
For example, to request an access token using the Device
Authorization Grant as defined by [RFC8628] after the user has
authorized the client on a separate device, the client makes the
following HTTP request using TLS (with extra line breaks for display
purposes only):
POST /token HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded
grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Adevice_code
&device_code=GmRhmhcxhwEzkoEqiMEg_DnyEysNkuNhszIySk9eS
&client_id=C409020731
If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh
token as described in Section 3.2.3. If the request failed client
authentication or is invalid, the authorization server returns an
error response as described in Section 3.2.3.1.
5. Accessing Protected Resources
The client accesses protected resources by presenting the access The client accesses protected resources by presenting the access
token to the resource server. The resource server MUST validate the token to the resource server. The resource server MUST validate the
access token and ensure that it has not expired and that its scope access token and ensure that it has not expired and that its scope
covers the requested resource. The methods used by the resource covers the requested resource. The methods used by the resource
server to validate the access token (as well as any error responses) server to validate the access token (as well as any error responses)
are beyond the scope of this specification, but generally involve an are beyond the scope of this specification, but generally involve an
interaction or coordination between the resource server and the interaction or coordination between the resource server and the
authorization server, such as using Token Introspection [RFC7662] or authorization server. For example, when the resource server and
a structured access token format such as a JWT authorization server are colocated or are part of the same system,
they may share a database or other storage; when the two components
are operated independently, they may use Token Introspection
[RFC7662] or a structured access token format such as a JWT
[I-D.ietf-oauth-access-token-jwt]. [I-D.ietf-oauth-access-token-jwt].
The method in which the client utilizes the access token to The method in which the client utilizes the access token to access
authenticate with the resource server depends on the type of access protected resources at the resource server depends on the type of
token issued by the authorization server. Typically, it involves access token issued by the authorization server. Typically, it
using the HTTP "Authorization" request header field [RFC2617] with an involves using the HTTP "Authorization" request header field
authentication scheme defined by the specification of the access [RFC7235] with an authentication scheme defined by the specification
token type used, such as "Bearer", defined below. of the access token type used, such as "Bearer", defined below.
7.1. Access Token Types 5.1. Access Token Types
The access token type provides the client with the information The access token type provides the client with the information
required to successfully utilize the access token to make a protected required to successfully utilize the access token to make a protected
resource request (along with type-specific attributes). The client resource request (along with type-specific attributes). The client
MUST NOT use an access token if it does not understand the token MUST NOT use an access token if it does not understand the token
type. type.
For example, the "Bearer" token type defined in this specification is For example, the "Bearer" token type defined in this specification is
utilized by simply including the access token string in the request: utilized by simply including the access token string in the request:
skipping to change at page 42, line 5 skipping to change at page 42, line 5
Host: example.com Host: example.com
Authorization: Bearer mF_9.B5f-4.1JqM Authorization: Bearer mF_9.B5f-4.1JqM
The above example is provided for illustration purposes only. The above example is provided for illustration purposes only.
Each access token type definition specifies the additional attributes Each access token type definition specifies the additional attributes
(if any) sent to the client together with the "access_token" response (if any) sent to the client together with the "access_token" response
parameter. It also defines the HTTP authentication method used to parameter. It also defines the HTTP authentication method used to
include the access token when making a protected resource request. include the access token when making a protected resource request.
7.2. Bearer Tokens 5.2. Bearer Tokens
A Bearer Token is a security token with the property that any party A Bearer Token is a security token with the property that any party
in possession of the token (a "bearer") can use the token in any way in possession of the token (a "bearer") can use the token in any way
that any other party in possession of it can. Using a bearer token that any other party in possession of it can. Using a bearer token
does not require a bearer to prove possession of cryptographic key does not require a bearer to prove possession of cryptographic key
material (proof-of-possession). material (proof-of-possession).
Bearer tokens may be extended to include proof-of-possession Bearer tokens may be extended to include proof-of-possession
techniques by other specifications. techniques by other specifications.
7.2.1. Authenticated Requests 5.2.1. Authenticated Requests
This section defines two methods of sending Bearer tokens in resource This section defines two methods of sending Bearer tokens in resource
requests to resource servers. Clients MUST NOT use more than one requests to resource servers. Clients MUST NOT use more than one
method to transmit the token in each request. method to transmit the token in each request.
7.2.1.1. Authorization Request Header Field 5.2.1.1. Authorization Request Header Field
When sending the access token in the "Authorization" request header When sending the access token in the "Authorization" request header
field defined by HTTP/1.1 [RFC2617], the client uses the "Bearer" field defined by HTTP/1.1 [RFC7235], the client uses the "Bearer"
authentication scheme to transmit the access token. authentication scheme to transmit the access token.
For example: For example:
GET /resource HTTP/1.1 GET /resource HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: Bearer mF_9.B5f-4.1JqM Authorization: Bearer mF_9.B5f-4.1JqM
The syntax of the "Authorization" header field for this scheme The syntax of the "Authorization" header field for this scheme
follows the usage of the Basic scheme defined in Section 2 of follows the usage of the Basic scheme defined in Section 2 of
skipping to change at page 43, line 5 skipping to change at page 43, line 5
syntax for Bearer credentials is as follows: syntax for Bearer credentials is as follows:
b64token = 1*( ALPHA / DIGIT / b64token = 1*( ALPHA / DIGIT /
"-" / "." / "_" / "~" / "+" / "/" ) *"=" "-" / "." / "_" / "~" / "+" / "/" ) *"="
credentials = "Bearer" 1*SP b64token credentials = "Bearer" 1*SP b64token
Clients SHOULD make authenticated requests with a bearer token using Clients SHOULD make authenticated requests with a bearer token using
the "Authorization" request header field with the "Bearer" HTTP the "Authorization" request header field with the "Bearer" HTTP
authorization scheme. Resource servers MUST support this method. authorization scheme. Resource servers MUST support this method.
7.2.1.2. Form-Encoded Body Parameter 5.2.1.2. Form-Encoded Body Parameter
When sending the access token in the HTTP request payload, the client When sending the access token in the HTTP request payload, the client
adds the access token to the request-body using the "access_token" adds the access token to the request-body using the "access_token"
parameter. The client MUST NOT use this method unless all of the parameter. The client MUST NOT use this method unless all of the
following conditions are met: following conditions are met:
* The HTTP request entity-header includes the "Content-Type" header * The HTTP request entity-header includes the "Content-Type" header
field set to "application/x-www-form-urlencoded". field set to "application/x-www-form-urlencoded".
* The payload follows the encoding requirements of the "application/ * The payload follows the encoding requirements of the "application/
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Host: server.example.com Host: server.example.com
Content-Type: application/x-www-form-urlencoded Content-Type: application/x-www-form-urlencoded
access_token=mF_9.B5f-4.1JqM access_token=mF_9.B5f-4.1JqM
The "application/x-www-form-urlencoded" method SHOULD NOT be used The "application/x-www-form-urlencoded" method SHOULD NOT be used
except in application contexts where participating clients do not except in application contexts where participating clients do not
have access to the "Authorization" request header field. Resource have access to the "Authorization" request header field. Resource
servers MAY support this method. servers MAY support this method.
7.2.2. The WWW-Authenticate Response Header Field 5.2.2. The WWW-Authenticate Response Header Field
If the protected resource request does not include authentication If the protected resource request does not include authentication
credentials or does not contain an access token that enables access credentials or does not contain an access token that enables access
to the protected resource, the resource server MUST include the HTTP to the protected resource, the resource server MUST include the HTTP
"WWW-Authenticate" response header field; it MAY include it in "WWW-Authenticate" response header field; it MAY include it in
response to other conditions as well. The "WWW-Authenticate" header response to other conditions as well. The "WWW-Authenticate" header
field uses the framework defined by HTTP/1.1 [RFC2617]. field uses the framework defined by HTTP/1.1 [RFC7235].
All challenges defined by this specification MUST use the auth-scheme All challenges for this token type MUST use the auth-scheme value
value "Bearer". This scheme MUST be followed by one or more auth- "Bearer". This scheme MUST be followed by one or more auth-param
param values. The auth-param attributes used or defined by this values. The auth-param attributes used or defined by this
specification are as follows. Other auth-param attributes MAY be specification for this token type are as follows. Other auth-param
used as well. attributes MAY be used as well.
A "realm" attribute MAY be included to indicate the scope of A "realm" attribute MAY be included to indicate the scope of
protection in the manner described in HTTP/1.1 [RFC2617]. The protection in the manner described in HTTP/1.1 [RFC7235]. The
"realm" attribute MUST NOT appear more than once. "realm" attribute MUST NOT appear more than once.
The "scope" attribute is defined in Section 3.3. The "scope" The "scope" attribute is defined in Section 3.2.2.1. The "scope"
attribute is a space-delimited list of case-sensitive scope values attribute is a space-delimited list of case-sensitive scope values
indicating the required scope of the access token for accessing the indicating the required scope of the access token for accessing the
requested resource. "scope" values are implementation defined; there requested resource. "scope" values are implementation defined; there
is no centralized registry for them; allowed values are defined by is no centralized registry for them; allowed values are defined by
the authorization server. The order of "scope" values is not the authorization server. The order of "scope" values is not
significant. In some cases, the "scope" value will be used when significant. In some cases, the "scope" value will be used when
requesting a new access token with sufficient scope of access to requesting a new access token with sufficient scope of access to
utilize the protected resource. Use of the "scope" attribute is utilize the protected resource. Use of the "scope" attribute is
OPTIONAL. The "scope" attribute MUST NOT appear more than once. The OPTIONAL. The "scope" attribute MUST NOT appear more than once. The
"scope" value is intended for programmatic use and is not meant to be "scope" value is intended for programmatic use and is not meant to be
skipping to change at page 44, line 49 skipping to change at page 44, line 49
Committee (OATC) Online Multimedia Authorization Protocol [OMAP] Committee (OATC) Online Multimedia Authorization Protocol [OMAP]
OAuth 2.0 use cases, respectively: OAuth 2.0 use cases, respectively:
scope="openid profile email" scope="openid profile email"
scope="urn:example:channel=HBO&urn:example:rating=G,PG-13" scope="urn:example:channel=HBO&urn:example:rating=G,PG-13"
If the protected resource request included an access token and failed If the protected resource request included an access token and failed
authentication, the resource server SHOULD include the "error" authentication, the resource server SHOULD include the "error"
attribute to provide the client with the reason why the access attribute to provide the client with the reason why the access
request was declined. The parameter value is described in request was declined. The parameter value is described in
Section 7.2.3. In addition, the resource server MAY include the Section 5.2.3. In addition, the resource server MAY include the
"error_description" attribute to provide developers a human-readable "error_description" attribute to provide developers a human-readable
explanation that is not meant to be displayed to end-users. It also explanation that is not meant to be displayed to end-users. It also
MAY include the "error_uri" attribute with an absolute URI MAY include the "error_uri" attribute with an absolute URI
identifying a human-readable web page explaining the error. The identifying a human-readable web page explaining the error. The
"error", "error_description", and "error_uri" attributes MUST NOT "error", "error_description", and "error_uri" attributes MUST NOT
appear more than once. appear more than once.
Values for the "scope" attribute (specified in Appendix A.4) MUST NOT Values for the "scope" attribute (specified in Appendix A.4) MUST NOT
include characters outside the set %x21 / %x23-5B / %x5D-7E for include characters outside the set %x21 / %x23-5B / %x5D-7E for
representing scope values and %x20 for delimiters between scope representing scope values and %x20 for delimiters between scope
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WWW-Authenticate: Bearer realm="example" WWW-Authenticate: Bearer realm="example"
And in response to a protected resource request with an And in response to a protected resource request with an
authentication attempt using an expired access token: authentication attempt using an expired access token:
HTTP/1.1 401 Unauthorized HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="example", WWW-Authenticate: Bearer realm="example",
error="invalid_token", error="invalid_token",
error_description="The access token expired" error_description="The access token expired"
7.2.3. Error Codes 5.2.3. Error Codes
When a request fails, the resource server responds using the When a request fails, the resource server responds using the
appropriate HTTP status code (typically, 400, 401, 403, or 405) and appropriate HTTP status code (typically, 400, 401, 403, or 405) and
includes one of the following error codes in the response: includes one of the following error codes in the response:
"invalid_request": The request is missing a required parameter, "invalid_request": The request is missing a required parameter,
includes an unsupported parameter or parameter value, repeats the includes an unsupported parameter or parameter value, repeats the
same parameter, uses more than one method for including an access same parameter, uses more than one method for including an access
token, or is otherwise malformed. The resource server SHOULD token, or is otherwise malformed. The resource server SHOULD
respond with the HTTP 400 (Bad Request) status code. respond with the HTTP 400 (Bad Request) status code.
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If the request lacks any authentication information (e.g., the client If the request lacks any authentication information (e.g., the client
was unaware that authentication is necessary or attempted using an was unaware that authentication is necessary or attempted using an
unsupported authentication method), the resource server SHOULD NOT unsupported authentication method), the resource server SHOULD NOT
include an error code or other error information. include an error code or other error information.
For example: For example:
HTTP/1.1 401 Unauthorized HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="example" WWW-Authenticate: Bearer realm="example"
7.3. Error Response 5.3. Error Response
If a resource access request fails, the resource server SHOULD inform If a resource access request fails, the resource server SHOULD inform
the client of the error. The method by which the resource server the client of the error. The method by which the resource server
does this is determined by the particular token type, such as the does this is determined by the particular token type, such as the
description of Bearer tokens in Section 7.2.3. description of Bearer tokens in Section 5.2.3.
7.3.1. Extension Token Types 5.3.1. Extension Token Types
[RFC6750] establishes a common registry in Section 11.4 [RFC6750] establishes a common registry in Section 11.4
(https://tools.ietf.org/html/rfc6749#section-11.4) for error values (https://tools.ietf.org/html/rfc6749#section-11.4) for error values
to be shared among OAuth token authentication schemes. to be shared among OAuth token authentication schemes.
New authentication schemes designed primarily for OAuth token New authentication schemes designed primarily for OAuth token
authentication SHOULD define a mechanism for providing an error authentication SHOULD define a mechanism for providing an error
status code to the client, in which the error values allowed are status code to the client, in which the error values allowed are
registered in the error registry established by this specification. registered in the error registry established by this specification.
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Other schemes capable of being used for OAuth token authentication, Other schemes capable of being used for OAuth token authentication,
but not primarily designed for that purpose, MAY bind their error but not primarily designed for that purpose, MAY bind their error
values to the registry in the same manner. values to the registry in the same manner.
New authentication schemes MAY choose to also specify the use of the New authentication schemes MAY choose to also specify the use of the
"error_description" and "error_uri" parameters to return error "error_description" and "error_uri" parameters to return error
information in a manner parallel to their usage in this information in a manner parallel to their usage in this
specification. specification.
7.4. Access Token Security Considerations 6. Extensibility
7.4.1. Security Threats 6.1. Defining Access Token Types
Access token types can be defined in one of two ways: registered in
the Access Token Types registry (following the procedures in
Section 11.1 of [RFC6749]), or by using a unique absolute URI as its
name.
Types utilizing a URI name SHOULD be limited to vendor-specific
implementations that are not commonly applicable, and are specific to
the implementation details of the resource server where they are
used.
All other types MUST be registered. Type names MUST conform to the
type-name ABNF. If the type definition includes a new HTTP
authentication scheme, the type name SHOULD be identical to the HTTP
authentication scheme name (as defined by [RFC2617]). The token type
"example" is reserved for use in examples.
type-name = 1*name-char
name-char = "-" / "." / "_" / DIGIT / ALPHA
6.2. Defining New Endpoint Parameters
New request or response parameters for use with the authorization
endpoint or the token endpoint are defined and registered in the
OAuth Parameters registry following the procedure in Section 11.2 of
[RFC6749].
Parameter names MUST conform to the param-name ABNF, and parameter
values syntax MUST be well-defined (e.g., using ABNF, or a reference
to the syntax of an existing parameter).
param-name = 1*name-char
name-char = "-" / "." / "_" / DIGIT / ALPHA
Unregistered vendor-specific parameter extensions that are not
commonly applicable and that are specific to the implementation
details of the authorization server where they are used SHOULD
utilize a vendor-specific prefix that is not likely to conflict with
other registered values (e.g., begin with 'companyname_').
6.3. Defining New Authorization Grant Types
New authorization grant types can be defined by assigning them a
unique absolute URI for use with the "grant_type" parameter. If the
extension grant type requires additional token endpoint parameters,
they MUST be registered in the OAuth Parameters registry as described
by Section 11.2 of [RFC6749].
6.4. Defining New Authorization Endpoint Response Types
New response types for use with the authorization endpoint are
defined and registered in the Authorization Endpoint Response Types
registry following the procedure in Section 11.3 of [RFC6749].
Response type names MUST conform to the response-type ABNF.
response-type = response-name *( SP response-name )
response-name = 1*response-char
response-char = "_" / DIGIT / ALPHA
If a response type contains one or more space characters (%x20), it
is compared as a space-delimited list of values in which the order of
values does not matter. Only one order of values can be registered,
which covers all other arrangements of the same set of values.
For example, an extension can define and register the "code
other_token" response type. Once registered, the same combination
cannot be registered as "other_token code", but both values can be
used to denote the same response type.
6.5. Defining Additional Error Codes
In cases where protocol extensions (i.e., access token types,
extension parameters, or extension grant types) require additional
error codes to be used with the authorization code grant error
response (Section 4.1.2.1), the token error response
(Section 3.2.3.1), or the resource access error response
(Section 5.3), such error codes MAY be defined.
Extension error codes MUST be registered (following the procedures in
Section 11.4 of [RFC6749]) if the extension they are used in
conjunction with is a registered access token type, a registered
endpoint parameter, or an extension grant type. Error codes used
with unregistered extensions MAY be registered.
Error codes MUST conform to the error ABNF and SHOULD be prefixed by
an identifying name when possible. For example, an error identifying
an invalid value set to the extension parameter "example" SHOULD be
named "example_invalid".
error = 1*error-char
error-char = %x20-21 / %x23-5B / %x5D-7E
7. Security Considerations
As a flexible and extensible framework, OAuth's security
considerations depend on many factors. The following sections
provide implementers with security guidelines focused on the three
client profiles described in Section 2.1: web application, browser-
based application, and native application.
A comprehensive OAuth security model and analysis, as well as
background for the protocol design, is provided by [RFC6819] and
[I-D.ietf-oauth-security-topics].
7.1. Access Token Security Considerations
7.1.1. Security Threats
The following list presents several common threats against protocols The following list presents several common threats against protocols
utilizing some form of tokens. This list of threats is based on NIST utilizing some form of tokens. This list of threats is based on NIST
Special Publication 800-63 [NIST800-63]. Special Publication 800-63 [NIST800-63].
7.4.1.1. Token manufacture/modification 7.1.1.1. Access token manufacture/modification
An attacker may generate a bogus token or modify the token contents An attacker may generate a bogus access token or modify the token
(such as the authentication or attribute statements) of an existing contents (such as the authentication or attribute statements) of an
token, causing the resource server to grant inappropriate access to existing token, causing the resource server to grant inappropriate
the client. For example, an attacker may modify the token to extend access to the client. For example, an attacker may modify the token
the validity period; a malicious client may modify the assertion to to extend the validity period; a malicious client may modify the
gain access to information that they should not be able to view. assertion to gain access to information that they should not be able
to view.
7.4.1.2. Token disclosure 7.1.1.2. Access token disclosure
Tokens may contain authentication and attribute statements that Access tokens may contain authentication and attribute statements
include sensitive information. that include sensitive information.
7.4.1.3. Token redirect 7.1.1.3. Access token redirect
An attacker uses a token generated for consumption by one resource An attacker uses an access token generated for consumption by one
server to gain access to a different resource server that mistakenly resource server to gain access to a different resource server that
believes the token to be for it. mistakenly believes the token to be for it.
7.4.1.4. Token replay 7.1.1.4. Access token replay
An attacker attempts to use a token that has already been used with An attacker attempts to use an access token that has already been
that resource server in the past. used with that resource server in the past.
7.4.2. Threat Mitigation 7.1.2. Threat Mitigation
A large range of threats can be mitigated by protecting the contents A large range of threats can be mitigated by protecting the contents
of the token by using a digital signature. Alternatively, a bearer of the access token by using a digital signature.
token can contain a reference to authorization information, rather
than encoding the information directly. Such references MUST be Alternatively, a bearer token can contain a reference to
infeasible for an attacker to guess; using a reference may require an authorization information, rather than encoding the information
extra interaction between a server and the token issuer to resolve directly. Such references MUST be infeasible for an attacker to
the reference to the authorization information. The mechanics of guess; using a reference may require an extra interaction between a
such an interaction are not defined by this specification. server and the access token issuer to resolve the reference to the
authorization information. The mechanics of such an interaction are
not defined by this specification.
This document does not specify the encoding or the contents of the This document does not specify the encoding or the contents of the
token; hence, detailed recommendations about the means of access token; hence, detailed recommendations about the means of
guaranteeing token integrity protection are outside the scope of this guaranteeing access token integrity protection are outside the scope
document. The token integrity protection MUST be sufficient to of this specification. The access token integrity protection MUST be
prevent the token from being modified. sufficient to prevent the token from being modified. One example of
an encoding and signing mechanism for access tokens is described in
[I-D.ietf-oauth-access-token-jwt].
To deal with token redirect, it is important for the authorization To deal with access token redirects, it is important for the
server to include the identity of the intended recipients (the authorization server to include the identity of the intended
audience), typically a single resource server (or a list of resource recipients (the audience), typically a single resource server (or a
servers), in the token. Restricting the use of the token to a list of resource servers), in the token. Restricting the use of the
specific scope is also RECOMMENDED. token to a specific scope is also RECOMMENDED.
The authorization server MUST implement TLS. Which version(s) ought The authorization server MUST implement TLS as described in Which
to be implemented will vary over time and will depend on the version(s) ought to be implemented will vary over time and will
widespread deployment and known security vulnerabilities at the time depend on the widespread deployment and known security
of implementation. vulnerabilities at the time of implementation. Refer to
Section 1.5.[BCP195] for up to date recommendations on transport
layer security.
To protect against token disclosure, confidentiality protection MUST To protect against access token disclosure, confidentiality
be applied using TLS with a ciphersuite that provides confidentiality protection MUST be applied using TLS with a ciphersuite that provides
and integrity protection. This requires that the communication confidentiality and integrity protection. This requires that the
interaction between the client and the authorization server, as well communication interaction between the client and the authorization
as the interaction between the client and the resource server, server, as well as the interaction between the client and the
utilize confidentiality and integrity protection. Since TLS is resource server, utilize confidentiality and integrity protection.
mandatory to implement and to use with this specification, it is the Since TLS is mandatory to implement and to use with this
preferred approach for preventing token disclosure via the specification, it is the preferred approach for preventing token
communication channel. For those cases where the client is prevented disclosure via the communication channel. For those cases where the
from observing the contents of the token, token encryption MUST be client is prevented from observing the contents of the access token,
applied in addition to the usage of TLS protection. As a further token encryption MUST be applied in addition to the usage of TLS
defense against token disclosure, the client MUST validate the TLS protection. As a further defense against token disclosure, the
certificate chain when making requests to protected resources, client MUST validate the TLS certificate chain when making requests
including checking the Certificate Revocation List (CRL) [RFC5280]. to protected resources, including checking the Certificate Revocation
List (CRL) [RFC5280].
Cookies are typically transmitted in the clear. Thus, any If cookies are transmitted without TLS protection, any information
information contained in them is at risk of disclosure. Therefore, contained in them is at risk of disclosure. Therefore, Bearer tokens
Bearer tokens MUST NOT be stored in cookies that can be sent in the MUST NOT be stored in cookies that can be sent in the clear, as any
clear, as any information in them is at risk of disclosure. See information in them is at risk of disclosure. See "HTTP State
"HTTP State Management Mechanism" [RFC6265] for security Management Mechanism" [RFC6265] for security considerations about
considerations about cookies. cookies.
In some deployments, including those utilizing load balancers, the In some deployments, including those utilizing load balancers, the
TLS connection to the resource server terminates prior to the actual TLS connection to the resource server terminates prior to the actual
server that provides the resource. This could leave the token server that provides the resource. This could leave the token
unprotected between the front-end server where the TLS connection unprotected between the front-end server where the TLS connection
terminates and the back-end server that provides the resource. In terminates and the back-end server that provides the resource. In
such deployments, sufficient measures MUST be employed to ensure such deployments, sufficient measures MUST be employed to ensure
confidentiality of the token between the front-end and back-end confidentiality of the access token between the front-end and back-
servers; encryption of the token is one such possible measure. end servers; encryption of the token is one such possible measure.
To deal with token capture and replay, the following recommendations To deal with access token capture and replay, the following
are made: First, the lifetime of the token MUST be limited; one means recommendations are made: First, the lifetime of the token MUST be
of achieving this is by putting a validity time field inside the limited; one means of achieving this is by putting a validity time
protected part of the token. Note that using short-lived (one hour field inside the protected part of the token. Note that using short-
or less) tokens reduces the impact of them being leaked. Second, lived tokens reduces the impact of them being leaked. Second,
confidentiality protection of the exchanges between the client and confidentiality protection of the exchanges between the client and
the authorization server and between the client and the resource the authorization server and between the client and the resource
server MUST be applied. As a consequence, no eavesdropper along the server MUST be applied. As a consequence, no eavesdropper along the
communication path is able to observe the token exchange. communication path is able to observe the token exchange.
Consequently, such an on-path adversary cannot replay the token. Consequently, such an on-path adversary cannot replay the token.
Furthermore, when presenting the token to a resource server, the Furthermore, when presenting the token to a resource server, the
client MUST verify the identity of that resource server, as per client MUST verify the identity of that resource server, as per
Section 3.1 of "HTTP Over TLS" [RFC2818]. Note that the client MUST [BCP195] and Section 3.1 of "HTTP Over TLS" [RFC2818]. Note that the
validate the TLS certificate chain when making these requests to client MUST validate the TLS certificate chain when making these
protected resources. Presenting the token to an unauthenticated and requests to protected resources. Presenting the token to an
unauthorized resource server or failing to validate the certificate unauthenticated and unauthorized resource server or failing to
chain will allow adversaries to steal the token and gain unauthorized validate the certificate chain will allow adversaries to steal the
access to protected resources. token and gain unauthorized access to protected resources.
7.4.3. Summary of Recommendations 7.1.3. Summary of Recommendations
7.4.3.1. Safeguard bearer tokens 7.1.3.1. Safeguard bearer tokens
Client implementations MUST ensure that bearer tokens are not leaked Client implementations MUST ensure that bearer tokens are not leaked
to unintended parties, as they will be able to use them to gain to unintended parties, as they will be able to use them to gain
access to protected resources. This is the primary security access to protected resources. This is the primary security
consideration when using bearer tokens and underlies all the more consideration when using bearer tokens and underlies all the more
specific recommendations that follow. specific recommendations that follow.
7.4.3.2. Validate TLS certificate chains 7.1.3.2. Validate TLS certificate chains
The client MUST validate the TLS certificate chain when making The client MUST validate the TLS certificate chain when making
requests to protected resources. Failing to do so may enable DNS requests to protected resources. Failing to do so may enable DNS
hijacking attacks to steal the token and gain unintended access. hijacking attacks to steal the token and gain unintended access.
7.4.3.3. Always use TLS (https) 7.1.3.3. Always use TLS (https)
Clients MUST always use TLS (https) or equivalent transport security Clients MUST always use TLS (https) or equivalent transport security
when making requests with bearer tokens. Failing to do so exposes when making requests with bearer tokens. Failing to do so exposes
the token to numerous attacks that could give attackers unintended the token to numerous attacks that could give attackers unintended
access. access.
7.4.3.4. Don't store bearer tokens in HTTP cookies 7.1.3.4. Don't store bearer tokens in HTTP cookies
Implementations MUST NOT store bearer tokens within cookies that can Implementations MUST NOT store bearer tokens within cookies that can
be sent in the clear (which is the default transmission mode for be sent in the clear (which is the default transmission mode for
cookies). Implementations that do store bearer tokens in cookies cookies). Implementations that do store bearer tokens in cookies
MUST take precautions against cross-site request forgery. MUST take precautions against cross-site request forgery.
7.4.3.5. Issue short-lived bearer tokens 7.1.3.5. Issue short-lived bearer tokens
Authorization servers SHOULD issue short-lived (one hour or less) Authorization servers SHOULD issue short-lived bearer tokens,
bearer tokens, particularly when issuing tokens to clients that run particularly when issuing tokens to clients that run within a web
within a web browser or other environments where information leakage browser or other environments where information leakage may occur.
may occur. Using short-lived bearer tokens can reduce the impact of Using short-lived bearer tokens can reduce the impact of them being
them being leaked. leaked.
7.4.3.6. Issue scoped bearer tokens 7.1.3.6. Issue scoped bearer tokens
Authorization servers SHOULD issue bearer tokens that contain an Authorization servers SHOULD issue bearer tokens that contain an
audience restriction, scoping their use to the intended relying party audience restriction, scoping their use to the intended relying party
or set of relying parties. or set of relying parties.
7.4.3.7. Don't pass bearer tokens in page URLs 7.1.3.7. Don't pass bearer tokens in page URLs
Bearer tokens MUST NOT be passed in page URLs (for example, as query Bearer tokens MUST NOT be passed in page URLs (for example, as query
string parameters). Instead, bearer tokens SHOULD be passed in HTTP string parameters). Instead, bearer tokens SHOULD be passed in HTTP
message headers or message bodies for which confidentiality measures message headers or message bodies for which confidentiality measures
are taken. Browsers, web servers, and other software may not are taken. Browsers, web servers, and other software may not
adequately secure URLs in the browser history, web server logs, and adequately secure URLs in the browser history, web server logs, and
other data structures. If bearer tokens are passed in page URLs, other data structures. If bearer tokens are passed in page URLs,
attackers might be able to steal them from the history data, logs, or attackers might be able to steal them from the history data, logs, or
other unsecured locations. other unsecured locations.
7.4.4. Token Replay Prevention 7.1.4. Token Replay Prevention
A sender-constrained access token scopes the applicability of an A sender-constrained access token scopes the applicability of an
access token to a certain sender. This sender is obliged to access token to a certain sender. This sender is obliged to
demonstrate knowledge of a certain secret as prerequisite for the demonstrate knowledge of a certain secret as prerequisite for the
acceptance of that access token at the recipient (e.g., a resource acceptance of that access token at the recipient (e.g., a resource
server). server).
Authorization and resource servers SHOULD use mechanisms for sender- Authorization and resource servers SHOULD use mechanisms for sender-
constrained access tokens to prevent token replay as described in constrained access tokens to prevent token replay as described in
Section 4.8.1.1.2 of [I-D.ietf-oauth-security-topics]. The use of Section 4.8.1.1.2 of [I-D.ietf-oauth-security-topics]. The use of
Mutual TLS for OAuth 2.0 [RFC8705] is RECOMMENDED. Mutual TLS for OAuth 2.0 [RFC8705] is RECOMMENDED.
It is RECOMMENDED to use end-to-end TLS. If TLS traffic needs to be It is RECOMMENDED to use end-to-end TLS. If TLS traffic needs to be
terminated at an intermediary, refer to Section 4.11 of terminated at an intermediary, refer to Section 4.11 of
[I-D.ietf-oauth-security-topics] for further security advice. [I-D.ietf-oauth-security-topics] for further security advice.
7.4.5. Access Token Privilege Restriction 7.1.5. Access Token Privilege Restriction
The privileges associated with an access token SHOULD be restricted The privileges associated with an access token SHOULD be restricted
to the minimum required for the particular application or use case. to the minimum required for the particular application or use case.
This prevents clients from exceeding the privileges authorized by the This prevents clients from exceeding the privileges authorized by the
resource owner. It also prevents users from exceeding their resource owner. It also prevents users from exceeding their
privileges authorized by the respective security policy. Privilege privileges authorized by the respective security policy. Privilege
restrictions also help to reduce the impact of access token leakage. restrictions also help to reduce the impact of access token leakage.
In particular, access tokens SHOULD be restricted to certain resource In particular, access tokens SHOULD be restricted to certain resource
servers (audience restriction), preferably to a single resource servers (audience restriction), preferably to a single resource
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effect, the authorization server associates the access token with the effect, the authorization server associates the access token with the
respective resource and actions and every resource server is obliged respective resource and actions and every resource server is obliged
to verify, for every request, whether the access token sent with that to verify, for every request, whether the access token sent with that
request was meant to be used for that particular action on the request was meant to be used for that particular action on the
particular resource. If not, the resource server must refuse to particular resource. If not, the resource server must refuse to
serve the respective request. Clients and authorization servers MAY serve the respective request. Clients and authorization servers MAY
utilize the parameter "scope" and "authorization_details" as utilize the parameter "scope" and "authorization_details" as
specified in [I-D.ietf-oauth-rar] to determine those resources and/or specified in [I-D.ietf-oauth-rar] to determine those resources and/or
actions. actions.
8. Extensibility 7.2. Client Authentication
8.1. Defining Access Token Types
Access token types can be defined in one of two ways: registered in
the Access Token Types registry (following the procedures in
Section 11.1 of [RFC6749]), or by using a unique absolute URI as its
name.
Types utilizing a URI name SHOULD be limited to vendor-specific
implementations that are not commonly applicable, and are specific to
the implementation details of the resource server where they are
used.
All other types MUST be registered. Type names MUST conform to the
type-name ABNF. If the type definition includes a new HTTP
authentication scheme, the type name SHOULD be identical to the HTTP
authentication scheme name (as defined by [RFC2617]). The token type
"example" is reserved for use in examples.
type-name = 1*name-char
name-char = "-" / "." / "_" / DIGIT / ALPHA
8.2. Defining New Endpoint Parameters
New request or response parameters for use with the authorization
endpoint or the token endpoint are defined and registered in the
OAuth Parameters registry following the procedure in Section 11.2 of
[RFC6749].
Parameter names MUST conform to the param-name ABNF, and parameter
values syntax MUST be well-defined (e.g., using ABNF, or a reference
to the syntax of an existing parameter).
param-name = 1*name-char
name-char = "-" / "." / "_" / DIGIT / ALPHA
Unregistered vendor-specific parameter extensions that are not
commonly applicable and that are specific to the implementation
details of the authorization server where they are used SHOULD
utilize a vendor-specific prefix that is not likely to conflict with
other registered values (e.g., begin with 'companyname_').
8.3. Defining New Authorization Grant Types
New authorization grant types can be defined by assigning them a
unique absolute URI for use with the "grant_type" parameter. If the
extension grant type requires additional token endpoint parameters,
they MUST be registered in the OAuth Parameters registry as described
by Section 11.2 of [RFC6749].
8.4. Defining New Authorization Endpoint Response Types
New response types for use with the authorization endpoint are
defined and registered in the Authorization Endpoint Response Types
registry following the procedure in Section 11.3 of [RFC6749].
Response type names MUST conform to the response-type ABNF.
response-type = response-name *( SP response-name )
response-name = 1*response-char
response-char = "_" / DIGIT / ALPHA
If a response type contains one or more space characters (%x20), it
is compared as a space-delimited list of values in which the order of
values does not matter. Only one order of values can be registered,
which covers all other arrangements of the same set of values.
For example, an extension can define and register the "code
other_token" response type. Once registered, the same combination
cannot be registered as "other_token code", but both values can be
used to denote the same response type.
8.5. Defining Additional Error Codes
In cases where protocol extensions (i.e., access token types,
extension parameters, or extension grant types) require additional
error codes to be used with the authorization code grant error
response (Section 4.1.2.1), the token error response (Section 5.2),
or the resource access error response (Section 7.3), such error codes
MAY be defined.
Extension error codes MUST be registered (following the procedures in
Section 11.4 of [RFC6749]) if the extension they are used in
conjunction with is a registered access token type, a registered
endpoint parameter, or an extension grant type. Error codes used
with unregistered extensions MAY be registered.
Error codes MUST conform to the error ABNF and SHOULD be prefixed by
an identifying name when possible. For example, an error identifying
an invalid value set to the extension parameter "example" SHOULD be
named "example_invalid".
error = 1*error-char
error-char = %x20-21 / %x23-5B / %x5D-7E
9. Security Considerations
As a flexible and extensible framework, OAuth's security
considerations depend on many factors. The following sections
provide implementers with security guidelines focused on the three
client profiles described in Section 2.1: web application, browser-
based application, and native application.
A comprehensive OAuth security model and analysis, as well as
background for the protocol design, is provided by [RFC6819] and
[I-D.ietf-oauth-security-topics].
9.1. Client Authentication
Authorization servers SHOULD use client authentication if possible.
It is RECOMMENDED to use asymmetric (public-key based) methods for
client authentication such as mTLS [RFC8705] or "private_key_jwt"
[OpenID]. When asymmetric methods for client authentication are
used, authorization servers do not need to store sensitive symmetric
keys, making these methods more robust against a number of attacks.
Authorization server MUST only rely on client authentication if the The authorization server MUST only rely on client authentication if
process of issuance/registration and distribution of the underlying the process of issuance/registration and distribution of the
credentials ensures their confidentiality. underlying credentials ensures their confidentiality.
When client authentication is not possible, the authorization server When client authentication is not possible, the authorization server
SHOULD employ other means to validate the client's identity - for SHOULD employ other means to validate the client's identity - for
example, by requiring the registration of the client redirect URI or example, by requiring the registration of the client redirect URI or
enlisting the resource owner to confirm identity. A valid redirect enlisting the resource owner to confirm identity. A valid redirect
URI is not sufficient to verify the client's identity when asking for URI is not sufficient to verify the client's identity when asking for
resource owner authorization but can be used to prevent delivering resource owner authorization but can be used to prevent delivering
credentials to a counterfeit client after obtaining resource owner credentials to a counterfeit client after obtaining resource owner
authorization. authorization.
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issued to such clients. issued to such clients.
The privileges an authorization server associates with a certain The privileges an authorization server associates with a certain
client identity MUST depend on the assessment of the overall process client identity MUST depend on the assessment of the overall process
for client identification and client credential lifecycle management. for client identification and client credential lifecycle management.
For example, authentication of a dynamically registered client just For example, authentication of a dynamically registered client just
ensures the authorization server it is talking to the same client ensures the authorization server it is talking to the same client
again. In contrast, if there is a web application whose developer's again. In contrast, if there is a web application whose developer's
identity was verified, who signed a contract and is issued a client identity was verified, who signed a contract and is issued a client
secret that is only used in a secure backend service, the secret that is only used in a secure backend service, the
authorization server might allow this client to access more sensible authorization server might allow this client to access more sensitive
services or to use the client credential grant type. services or to use the client credentials grant type.
9.1.1. Client Authentication of Native Apps 7.2.1. Client Authentication of Native Apps
Secrets that are statically included as part of an app distributed to Secrets that are statically included as part of an app distributed to
multiple users should not be treated as confidential secrets, as one multiple users should not be treated as confidential secrets, as one
user may inspect their copy and learn the shared secret. For this user may inspect their copy and learn the shared secret. For this
reason, it is NOT RECOMMENDED for authorization servers to require reason, it is NOT RECOMMENDED for authorization servers to require
client authentication of public native apps clients using a shared client authentication of public native apps clients using a shared
secret, as this serves little value beyond client identification secret, as this serves little value beyond client identification
which is already provided by the "client_id" request parameter. which is already provided by the "client_id" request parameter.
Authorization servers that still require a statically included shared Authorization servers that still require a statically included shared
secret for native app clients MUST treat the client as a public secret for native app clients MUST treat the client as a public
client (as defined in Section 2.1), and not accept the secret as client (as defined in Section 2.1), and not accept the secret as
proof of the client's identity. Without additional measures, such proof of the client's identity. Without additional measures, such
clients are subject to client impersonation (see Section 9.3.1). clients are subject to client impersonation (see Section 7.4.1).
9.2. Registration of Native App Clients 7.3. Registration of Native App Clients
Except when using a mechanism like Dynamic Client Registration Except when using a mechanism like Dynamic Client Registration
[RFC7591] to provision per-instance secrets, native apps are [RFC7591] to provision per-instance secrets, native apps are
classified as public clients, as defined in Section 2.1; they MUST be classified as public clients, as defined in Section 2.1; they MUST be
registered with the authorization server as such. Authorization registered with the authorization server as such. Authorization
servers MUST record the client type in the client registration servers MUST record the client type in the client registration
details in order to identify and process requests accordingly. details in order to identify and process requests accordingly.
Authorization servers MUST require clients to register their complete
redirect URI (including the path component) and reject authorization
requests that specify a redirect URI that doesn't exactly match the
one that was registered; the exception is loopback redirects, where
an exact match is required except for the port URI component.
For private-use URI scheme-based redirects, authorization servers
SHOULD enforce the requirement in Section 10.3.1 that clients use
schemes that are reverse domain name based. At a minimum, any
private-use URI scheme that doesn't contain a period character (".")
SHOULD be rejected.
In addition to the collision-resistant properties, requiring a URI
scheme based on a domain name that is under the control of the app
can help to prove ownership in the event of a dispute where two apps
claim the same private-use URI scheme (where one app is acting
maliciously). For example, if two apps claimed "com.example.app",
the owner of "example.com" could petition the app store operator to
remove the counterfeit app. Such a petition is harder to prove if a
generic URI scheme was used.
Authorization servers MAY request the inclusion of other platform- Authorization servers MAY request the inclusion of other platform-
specific information, such as the app package or bundle name, or specific information, such as the app package or bundle name, or
other information that may be useful for verifying the calling app's other information that may be useful for verifying the calling app's
identity on operating systems that support such functions. identity on operating systems that support such functions.
9.3. Client Impersonation For private-use URI scheme-based redirect URIs, authorization servers
SHOULD require that the URI scheme be based on a domain name that is
under the control of the app. In addition to the collision-resistant
properties, this can help to prove ownership in the event of a
dispute where two apps claim the same private-use URI scheme (where
one app is acting maliciously). For example, if two apps claimed
"com.example.app", the owner of "example.com" could petition the app
store operator to remove the counterfeit app. Such a petition is
harder to prove if a generic URI scheme was used.
7.4. Client Impersonation
A malicious client can impersonate another client and obtain access A malicious client can impersonate another client and obtain access
to protected resources if the impersonated client fails to, or is to protected resources if the impersonated client fails to, or is
unable to, keep its client credentials confidential. unable to, keep its client credentials confidential.
The authorization server MUST authenticate the client whenever
possible. If the authorization server cannot authenticate the client
due to the client's nature, the authorization server MUST require the
registration of any redirect URI used for receiving authorization
responses and SHOULD utilize other means to protect resource owners
from such potentially malicious clients. For example, the
authorization server can engage the resource owner to assist in
identifying the client and its origin.
The authorization server SHOULD enforce explicit resource owner The authorization server SHOULD enforce explicit resource owner
authentication and provide the resource owner with information about authentication and provide the resource owner with information about
the client and the requested authorization scope and lifetime. It is the client and the requested authorization scope and lifetime. It is
up to the resource owner to review the information in the context of up to the resource owner to review the information in the context of
the current client and to authorize or deny the request. the current client and to authorize or deny the request.
The authorization server SHOULD NOT process repeated authorization The authorization server SHOULD NOT process repeated authorization
requests automatically (without active resource owner interaction) requests automatically (without active resource owner interaction)
without authenticating the client or relying on other measures to without authenticating the client or relying on other measures to
ensure that the repeated request comes from the original client and ensure that the repeated request comes from the original client and
not an impersonator. not an impersonator.
9.3.1. Impersonation of Native Apps 7.4.1. Impersonation of Native Apps
As stated above, the authorization server SHOULD NOT process As stated above, the authorization server SHOULD NOT process
authorization requests automatically without user consent or authorization requests automatically without user consent or
interaction, except when the identity of the client can be assured. interaction, except when the identity of the client can be assured.
This includes the case where the user has previously approved an This includes the case where the user has previously approved an
authorization request for a given client id - unless the identity of authorization request for a given client ID - unless the identity of
the client can be proven, the request SHOULD be processed as if no the client can be proven, the request SHOULD be processed as if no
previous request had been approved. previous request had been approved.
Measures such as claimed "https" scheme redirects MAY be accepted by Measures such as claimed "https" scheme redirects MAY be accepted by
authorization servers as identity proof. Some operating systems may authorization servers as identity proof. Some operating systems may
offer alternative platform-specific identity features that MAY be offer alternative platform-specific identity features that MAY be
accepted, as appropriate. accepted, as appropriate.
9.4. Access Tokens 7.4.2. Access Token Privilege Restriction
Access token credentials (as well as any confidential access token
attributes) MUST be kept confidential in transit and storage, and
only shared among the authorization server, the resource servers the
access token is valid for, and the client to whom the access token is
issued. Access token credentials MUST only be transmitted using TLS
as described in Section 1.6 with server authentication as defined by
[RFC2818].
The authorization server MUST ensure that access tokens cannot be
generated, modified, or guessed to produce valid access tokens by
unauthorized parties.
9.4.1. Access Token Privilege Restriction
The client SHOULD request access tokens with the minimal scope The client SHOULD request access tokens with the minimal scope
necessary. The authorization server SHOULD take the client identity necessary. The authorization server SHOULD take the client identity
into account when choosing how to honor the requested scope and MAY into account when choosing how to honor the requested scope and MAY
issue an access token with less rights than requested. issue an access token with less rights than requested.
The privileges associated with an access token SHOULD be restricted The privileges associated with an access token SHOULD be restricted
to the minimum required for the particular application or use case. to the minimum required for the particular application or use case.
This prevents clients from exceeding the privileges authorized by the This prevents clients from exceeding the privileges authorized by the
resource owner. It also prevents users from exceeding their resource owner. It also prevents users from exceeding their
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server. To put this into effect, the authorization server associates server. To put this into effect, the authorization server associates
the access token with certain resource servers and every resource the access token with certain resource servers and every resource
server is obliged to verify, for every request, whether the access server is obliged to verify, for every request, whether the access
token sent with that request was meant to be used for that particular token sent with that request was meant to be used for that particular
resource server. If not, the resource server MUST refuse to serve resource server. If not, the resource server MUST refuse to serve
the respective request. Clients and authorization servers MAY the respective request. Clients and authorization servers MAY
utilize the parameters "scope" or "resource" as specified in utilize the parameters "scope" or "resource" as specified in
[RFC8707], respectively, to determine the resource server they want [RFC8707], respectively, to determine the resource server they want
to access. to access.
9.4.2. Access Token Replay Prevention 7.4.3. Access Token Replay Prevention
Additionally, access tokens SHOULD be restricted to certain resources Additionally, access tokens SHOULD be restricted to certain resources
and actions on resource servers or resources. To put this into and actions on resource servers or resources. To put this into
effect, the authorization server associates the access token with the effect, the authorization server associates the access token with the
respective resource and actions and every resource server is obliged respective resource and actions and every resource server is obliged
to verify, for every request, whether the access token sent with that to verify, for every request, whether the access token sent with that
request was meant to be used for that particular action on the request was meant to be used for that particular action on the
particular resource. If not, the resource server must refuse to particular resource. If not, the resource server must refuse to
serve the respective request. Clients and authorization servers MAY serve the respective request. Clients and authorization servers MAY
utilize the parameter "scope" and "authorization_details" as utilize the parameter "scope" and "authorization_details" as
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Authorization and resource servers SHOULD use mechanisms for sender- Authorization and resource servers SHOULD use mechanisms for sender-
constrained access tokens to prevent token replay as described in constrained access tokens to prevent token replay as described in
(#pop_tokens). A sender-constrained access token scopes the (#pop_tokens). A sender-constrained access token scopes the
applicability of an access token to a certain sender. This sender is applicability of an access token to a certain sender. This sender is
obliged to demonstrate knowledge of a certain secret as prerequisite obliged to demonstrate knowledge of a certain secret as prerequisite
for the acceptance of that access token at the recipient (e.g., a for the acceptance of that access token at the recipient (e.g., a
resource server). The use of Mutual TLS for OAuth 2.0 [RFC8705] is resource server). The use of Mutual TLS for OAuth 2.0 [RFC8705] is
RECOMMENDED. RECOMMENDED.
9.5. Refresh Tokens 7.5. Refresh Tokens
Authorization servers MAY issue refresh tokens to clients. Authorization servers MAY issue refresh tokens to clients.
Refresh tokens MUST be kept confidential in transit and storage, and Refresh tokens MUST be kept confidential in transit and storage, and
shared only among the authorization server and the client to whom the shared only among the authorization server and the client to whom the
refresh tokens were issued. The authorization server MUST maintain refresh tokens were issued. The authorization server MUST maintain
the binding between a refresh token and the client to whom it was the binding between a refresh token and the client to whom it was
issued. Refresh tokens MUST only be transmitted using TLS as issued. Refresh tokens MUST only be transmitted using TLS as
described in Section 1.6 with server authentication as defined by described in Section 1.5 with server authentication as defined by
[RFC2818]. [RFC2818].
The authorization server MUST verify the binding between the refresh The authorization server MUST verify the binding between the refresh
token and client identity whenever the client identity can be token and client identity whenever the client identity can be
authenticated. When client authentication is not possible, the authenticated. When client authentication is not possible, the
authorization server SHOULD issue sender-constrained refresh tokens authorization server SHOULD issue sender-constrained refresh tokens
or use refresh token rotation as described in (#refreshing-an-access- or use refresh token rotation as described in (#refreshing-an-access-
token). token).
The authorization server MUST ensure that refresh tokens cannot be The authorization server MUST ensure that refresh tokens cannot be
generated, modified, or guessed to produce valid refresh tokens by generated, modified, or guessed to produce valid refresh tokens by
unauthorized parties. unauthorized parties.
9.6. Client Impersonating Resource Owner 7.6. Client Impersonating Resource Owner
Resource servers may make access control decisions based on the Resource servers may make access control decisions based on the
identity of the resource owner as communicated in the "sub" claim identity of the resource owner as communicated in the "sub" claim
returned by the authorization server in a token introspection returned by the authorization server in a token introspection
response [RFC7662] or other mechanisms. If a client is able to response [RFC7662] or other mechanisms. If a client is able to
choose its own "client_id" during registration with the authorization choose its own "client_id" during registration with the authorization
server, then there is a risk that it can register with the same "sub" server, then there is a risk that it can register with the same "sub"
value as a privileged user. A subsequent access token obtained under value as a privileged user. A subsequent access token obtained under
the client credentials grant may be mistaken for an access token the client credentials grant may be mistaken for an access token
authorized by the privileged user if the resource server does not authorized by the privileged user if the resource server does not
perform additional checks. perform additional checks.
Authorization servers SHOULD NOT allow clients to influence their Authorization servers SHOULD NOT allow clients to influence their
"client_id" or "sub" value or any other claim if that can cause "client_id" or "sub" value or any other claim if that can cause
confusion with a genuine resource owner. Where this cannot be confusion with a genuine resource owner. Where this cannot be
avoided, authorization servers MUST provide other means for the avoided, authorization servers MUST provide other means for the
resource server to distinguish between access tokens authorized by a resource server to distinguish between access tokens authorized by a
resource owner from access tokens authorized by the client itself. resource owner from access tokens authorized by the client itself.
9.7. Protecting Redirect-Based Flows 7.7. Protecting the Authorization Code Flow
When comparing client redirect URIs against pre-registered URIs, When comparing client redirect URIs against pre-registered URIs,
authorization servers MUST utilize exact string matching. This authorization servers MUST utilize exact string matching. This
measure contributes to the prevention of leakage of authorization measure contributes to the prevention of leakage of authorization
codes and access tokens (see (#insufficient_uri_validation)). It can codes and access tokens (see (#insufficient_uri_validation)). It can
also help to detect mix-up attacks (see (#mix_up)). also help to detect mix-up attacks (see (#mix_up)).
Clients MUST NOT expose URLs that forward the user's browser to Clients MUST NOT expose URLs that forward the user's browser to
arbitrary URIs obtained from a query parameter ("open redirector"). arbitrary URIs obtained from a query parameter ("open redirector").
Open redirectors can enable exfiltration of authorization codes and Open redirectors can enable exfiltration of authorization codes and
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provides CSRF protection. Otherwise, one-time use CSRF tokens provides CSRF protection. Otherwise, one-time use CSRF tokens
carried in the "state" parameter that are securely bound to the user carried in the "state" parameter that are securely bound to the user
agent MUST be used for CSRF protection (see (#csrf_countermeasures)). agent MUST be used for CSRF protection (see (#csrf_countermeasures)).
In order to prevent mix-up attacks (see (#mix_up)), clients MUST only In order to prevent mix-up attacks (see (#mix_up)), clients MUST only
process redirect responses of the authorization server they sent the process redirect responses of the authorization server they sent the
respective request to and from the same user agent this authorization respective request to and from the same user agent this authorization
request was initiated with. Clients MUST store the authorization request was initiated with. Clients MUST store the authorization
server they sent an authorization request to and bind this server they sent an authorization request to and bind this
information to the user agent and check that the authorization information to the user agent and check that the authorization
request was received from the correct authorization server. Clients response was received from the correct authorization server. Clients
MUST ensure that the subsequent access token request, if applicable, MUST ensure that the subsequent access token request, if applicable,
is sent to the same authorization server. Clients SHOULD use is sent to the same authorization server. Clients SHOULD use
distinct redirect URIs for each authorization server as a means to distinct redirect URIs for each authorization server as a means to
identify the authorization server a particular response came from. identify the authorization server a particular response came from.
An AS that redirects a request potentially containing user An AS that redirects a request potentially containing user
credentials MUST avoid forwarding these user credentials accidentally credentials MUST avoid forwarding these user credentials accidentally
(see Section 9.7.2 for details). (see Section 7.7.2 for details).
9.7.1. Loopback Redirect Considerations in Native Apps 7.7.1. Loopback Redirect Considerations in Native Apps
Loopback interface redirect URIs use the "http" scheme (i.e., without Loopback interface redirect URIs use the "http" scheme (i.e., without
Transport Layer Security (TLS)). This is acceptable for loopback Transport Layer Security (TLS)). This is acceptable for loopback
interface redirect URIs as the HTTP request never leaves the device. interface redirect URIs as the HTTP request never leaves the device.
Clients should open the network port only when starting the Clients should open the network port only when starting the
authorization request and close it once the response is returned. authorization request and close it once the response is returned.
Clients should listen on the loopback network interface only, in Clients should listen on the loopback network interface only, in
order to avoid interference by other network actors. order to avoid interference by other network actors.
While redirect URIs using localhost (i.e., While redirect URIs using localhost (i.e.,
"http://localhost:{port}/{path}") function similarly to loopback IP "http://localhost:{port}/{path}") function similarly to loopback IP
redirects described in Section 10.3.3, the use of "localhost" is NOT redirects described in Section 8.3.3, the use of "localhost" is NOT
RECOMMENDED. Specifying a redirect URI with the loopback IP literal RECOMMENDED. Specifying a redirect URI with the loopback IP literal
rather than "localhost" avoids inadvertently listening on network rather than "localhost" avoids inadvertently listening on network
interfaces other than the loopback interface. It is also less interfaces other than the loopback interface. It is also less
susceptible to client-side firewalls and misconfigured host name susceptible to client-side firewalls and misconfigured host name
resolution on the user's device. resolution on the user's device.
9.7.2. HTTP 307 Redirect 7.7.2. HTTP 307 Redirect
An AS which redirects a request that potentially contains user An AS which redirects a request that potentially contains user
credentials MUST NOT use the HTTP 307 status code for redirection. credentials MUST NOT use the HTTP 307 status code for redirection.
If an HTTP redirection (and not, for example, JavaScript) is used for If an HTTP redirection (and not, for example, JavaScript) is used for
such a request, AS SHOULD use HTTP status code 303 "See Other". such a request, AS SHOULD use HTTP status code 303 "See Other".
At the authorization endpoint, a typical protocol flow is that the AS At the authorization endpoint, a typical protocol flow is that the AS
prompts the user to enter their credentials in a form that is then prompts the user to enter their credentials in a form that is then
submitted (using the HTTP POST method) back to the authorization submitted (using the HTTP POST method) back to the authorization
server. The AS checks the credentials and, if successful, redirects server. The AS checks the credentials and, if successful, redirects
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In the HTTP standard [RFC7231], only the status code 303 In the HTTP standard [RFC7231], only the status code 303
unambigiously enforces rewriting the HTTP POST request to an HTTP GET unambigiously enforces rewriting the HTTP POST request to an HTTP GET
request. For all other status codes, including the popular 302, user request. For all other status codes, including the popular 302, user
agents can opt not to rewrite POST to GET requests and therefore to agents can opt not to rewrite POST to GET requests and therefore to
reveal the user credentials to the client. (In practice, however, reveal the user credentials to the client. (In practice, however,
most user agents will only show this behaviour for 307 redirects.) most user agents will only show this behaviour for 307 redirects.)
Therefore, the RECOMMENDED status code for HTTP redirects is 303. Therefore, the RECOMMENDED status code for HTTP redirects is 303.
9.8. Authorization Codes 7.8. Authorization Codes
The transmission of authorization codes MUST be made over a secure
channel, and the client MUST require the use of TLS with its redirect
URI if the URI identifies a network resource. Since authorization
codes are transmitted via user-agent redirections, they could
potentially be disclosed through user-agent history and HTTP referrer
headers.
Authorization codes MUST be short lived and single-use. If the Authorization codes MUST be short lived and single-use. If the
authorization server observes multiple attempts to exchange an authorization server observes multiple attempts to exchange an
authorization code for an access token, the authorization server authorization code for an access token, the authorization server
SHOULD attempt to revoke all refresh and access tokens already SHOULD attempt to revoke all refresh and access tokens already
granted based on the compromised authorization code. granted based on the compromised authorization code.
If the client can be authenticated, the authorization servers MUST If the client can be authenticated, the authorization servers MUST
authenticate the client and ensure that the authorization code was authenticate the client and ensure that the authorization code was
issued to the same client. issued to the same client.
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that can read the authorization request (cf. Attacker A4 in that can read the authorization request (cf. Attacker A4 in
(#secmodel)) can break the security provided by this mechanism. (#secmodel)) can break the security provided by this mechanism.
Currently, "S256" is the only such method. Currently, "S256" is the only such method.
When an authorization code arrives at the token endpoint, the When an authorization code arrives at the token endpoint, the
authorization server MUST do the following check: authorization server MUST do the following check:
1. If there was a "code_challenge" in the authorization request for 1. If there was a "code_challenge" in the authorization request for
which this code was issued, there must be a "code_verifier" in which this code was issued, there must be a "code_verifier" in
the token request, and it MUST be verified according to the steps the token request, and it MUST be verified according to the steps
in Section 4.1.3. (This is no change from the current behavior in Section 3.2.2. (This is no change from the current behavior
in [RFC7636].) in [RFC7636].)
2. If there was no "code_challenge" in the authorization request, 2. If there was no "code_challenge" in the authorization request,
any request to the token endpoint containing a "code_verifier" any request to the token endpoint containing a "code_verifier"
MUST be rejected. MUST be rejected.
Authorization servers MUST support the "code_challenge" and Authorization servers MUST support the "code_challenge" and
"code_verifier" parameters. "code_verifier" parameters.
Authorization servers MUST provide a way to detect their support for Authorization servers MUST provide a way to detect their support for
the "code_challenge" mechanism. To this end, they MUST either (a) the "code_challenge" mechanism. To this end, they MUST either (a)
publish the element "code_challenge_methods_supported" in their AS publish the element "code_challenge_methods_supported" in their AS
metadata ([RFC8414]) containing the supported metadata ([RFC8414]) containing the supported
"code_challenge_method"s (which can be used by the client to detect "code_challenge_method"s (which can be used by the client to detect
support) or (b) provide a deployment-specific way to ensure or support) or (b) provide a deployment-specific way to ensure or
determine support by the AS. determine support by the AS.
9.9. Request Confidentiality 7.9. Request Confidentiality
Access tokens, refresh tokens, authorization codes, and client Access tokens, refresh tokens, authorization codes, and client
credentials MUST NOT be transmitted in the clear. credentials MUST NOT be transmitted in the clear.
The "state" and "scope" parameters SHOULD NOT include sensitive The "state" and "scope" parameters SHOULD NOT include sensitive
client or resource owner information in plain text, as they can be client or resource owner information in plain text, as they can be
transmitted over insecure channels or stored insecurely. transmitted over insecure channels or stored insecurely.
9.10. Ensuring Endpoint Authenticity 7.10. Ensuring Endpoint Authenticity
In order to prevent man-in-the-middle attacks, the authorization In order to prevent man-in-the-middle attacks, the authorization
server MUST require the use of TLS with server authentication as server MUST require the use of TLS with server authentication as
defined by [RFC2818] for any request sent to the authorization and defined by [RFC2818] for any request sent to the authorization and
token endpoints. The client MUST validate the authorization server's token endpoints. The client MUST validate the authorization server's
TLS certificate as defined by [RFC6125] and in accordance with its TLS certificate as defined by [RFC6125] and in accordance with its
requirements for server identity authentication. requirements for server identity authentication.
9.11. Credentials-Guessing Attacks 7.11. Credentials-Guessing Attacks
The authorization server MUST prevent attackers from guessing access The authorization server MUST prevent attackers from guessing access
tokens, authorization codes, refresh tokens, resource owner tokens, authorization codes, refresh tokens, resource owner
passwords, and client credentials. passwords, and client credentials.
The probability of an attacker guessing generated tokens (and other The probability of an attacker guessing generated tokens (and other
credentials not intended for handling by end-users) MUST be less than credentials not intended for handling by end-users) MUST be less than
or equal to 2^(-128) and SHOULD be less than or equal to 2^(-160). or equal to 2^(-128) and SHOULD be less than or equal to 2^(-160).
The authorization server MUST utilize other means to protect The authorization server MUST utilize other means to protect
credentials intended for end-user usage. credentials intended for end-user usage.
9.12. Phishing Attacks 7.12. Phishing Attacks
Wide deployment of this and similar protocols may cause end-users to Wide deployment of this and similar protocols may cause end-users to
become inured to the practice of being redirected to websites where become inured to the practice of being redirected to websites where
they are asked to enter their passwords. If end-users are not they are asked to enter their passwords. If end-users are not
careful to verify the authenticity of these websites before entering careful to verify the authenticity of these websites before entering
their credentials, it will be possible for attackers to exploit this their credentials, it will be possible for attackers to exploit this
practice to steal resource owners' passwords. practice to steal resource owners' passwords.
Service providers should attempt to educate end-users about the risks Service providers should attempt to educate end-users about the risks
phishing attacks pose and should provide mechanisms that make it easy phishing attacks pose and should provide mechanisms that make it easy
for end-users to confirm the authenticity of their sites. Client for end-users to confirm the authenticity of their sites. Client
developers should consider the security implications of how they developers should consider the security implications of how they
interact with the user-agent (e.g., external, embedded), and the interact with the user agent (e.g., external, embedded), and the
ability of the end-user to verify the authenticity of the ability of the end-user to verify the authenticity of the
authorization server. authorization server.
To reduce the risk of phishing attacks, the authorization servers To reduce the risk of phishing attacks, the authorization servers
MUST require the use of TLS on every endpoint used for end-user MUST require the use of TLS on every endpoint used for end-user
interaction. interaction.
9.13. Fake External User-Agents in Native Apps 7.13. Fake External User-Agents in Native Apps
The native app that is initiating the authorization request has a The native app that is initiating the authorization request has a
large degree of control over the user interface and can potentially large degree of control over the user interface and can potentially
present a fake external user-agent, that is, an embedded user-agent present a fake external user agent, that is, an embedded user agent
made to appear as an external user-agent. made to appear as an external user agent.
When all good actors are using external user-agents, the advantage is When all good actors are using external user agents, the advantage is
that it is possible for security experts to detect bad actors, as that it is possible for security experts to detect bad actors, as
anyone faking an external user-agent is provably bad. On the other anyone faking an external user agent is provably bad. On the other
hand, if good and bad actors alike are using embedded user-agents, hand, if good and bad actors alike are using embedded user agents,
bad actors don't need to fake anything, making them harder to detect. bad actors don't need to fake anything, making them harder to detect.
Once a malicious app is detected, it may be possible to use this Once a malicious app is detected, it may be possible to use this
knowledge to blacklist the app's signature in malware scanning knowledge to blacklist the app's signature in malware scanning
software, take removal action (in the case of apps distributed by app software, take removal action (in the case of apps distributed by app
stores) and other steps to reduce the impact and spread of the stores) and other steps to reduce the impact and spread of the
malicious app. malicious app.
Authorization servers can also directly protect against fake external Authorization servers can also directly protect against fake external
user-agents by requiring an authentication factor only available to user agents by requiring an authentication factor only available to
true external user-agents. true external user agents.
Users who are particularly concerned about their security when using Users who are particularly concerned about their security when using
in-app browser tabs may also take the additional step of opening the in-app browser tabs may also take the additional step of opening the
request in the full browser from the in-app browser tab and complete request in the full browser from the in-app browser tab and complete
the authorization there, as most implementations of the in-app the authorization there, as most implementations of the in-app
browser tab pattern offer such functionality. browser tab pattern offer such functionality.
9.14. Malicious External User-Agents in Native Apps 7.14. Malicious External User-Agents in Native Apps
If a malicious app is able to configure itself as the default handler If a malicious app is able to configure itself as the default handler
for "https" scheme URIs in the operating system, it will be able to for "https" scheme URIs in the operating system, it will be able to
intercept authorization requests that use the default browser and intercept authorization requests that use the default browser and
abuse this position of trust for malicious ends such as phishing the abuse this position of trust for malicious ends such as phishing the
user. user.
This attack is not confined to OAuth; a malicious app configured in This attack is not confined to OAuth; a malicious app configured in
this way would present a general and ongoing risk to the user beyond this way would present a general and ongoing risk to the user beyond
OAuth usage by native apps. Many operating systems mitigate this OAuth usage by native apps. Many operating systems mitigate this
issue by requiring an explicit user action to change the default issue by requiring an explicit user action to change the default
handler for "http" and "https" scheme URIs. handler for "http" and "https" scheme URIs.
9.15. Cross-Site Request Forgery 7.15. Cross-Site Request Forgery
An attacker might attempt to inject a request to the redirect URI of An attacker might attempt to inject a request to the redirect URI of
the legitimate client on the victim's device, e.g., to cause the the legitimate client on the victim's device, e.g., to cause the
client to access resources under the attacker's control. This is a client to access resources under the attacker's control. This is a
variant of an attack known as Cross-Site Request Forgery (CSRF). variant of an attack known as Cross-Site Request Forgery (CSRF).
The traditional countermeasure are CSRF tokens that are bound to the The traditional countermeasure are CSRF tokens that are bound to the
user agent and passed in the "state" parameter to the authorization user agent and passed in the "state" parameter to the authorization
server as described in [RFC6819]. The same protection is provided by server as described in [RFC6819]. The same protection is provided by
the "code_verifier" parameter or the OpenID Connect "nonce" value. the "code_verifier" parameter or the OpenID Connect "nonce" value.
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* If "state" is used for carrying application state, and integrity * If "state" is used for carrying application state, and integrity
of its contents is a concern, clients MUST protect "state" against of its contents is a concern, clients MUST protect "state" against
tampering and swapping. This can be achieved by binding the tampering and swapping. This can be achieved by binding the
contents of state to the browser session and/or signed/encrypted contents of state to the browser session and/or signed/encrypted
state values [I-D.bradley-oauth-jwt-encoded-state]. state values [I-D.bradley-oauth-jwt-encoded-state].
AS therefore MUST provide a way to detect their supported code AS therefore MUST provide a way to detect their supported code
challenge methods either via AS metadata according to [RFC8414] or challenge methods either via AS metadata according to [RFC8414] or
provide a deployment-specific way to ensure or determine support. provide a deployment-specific way to ensure or determine support.
9.16. Clickjacking 7.16. Clickjacking
As described in Section 4.4.1.9 of [RFC6819], the authorization As described in Section 4.4.1.9 of [RFC6819], the authorization
request is susceptible to clickjacking. An attacker can use this request is susceptible to clickjacking. An attacker can use this
vector to obtain the user's authentication credentials, change the vector to obtain the user's authentication credentials, change the
scope of access granted to the client, and potentially access the scope of access granted to the client, and potentially access the
user's resources. user's resources.
Authorization servers MUST prevent clickjacking attacks. Multiple Authorization servers MUST prevent clickjacking attacks. Multiple
countermeasures are described in [RFC6819], including the use of the countermeasures are described in [RFC6819], including the use of the
X-Frame-Options HTTP response header field and frame-busting X-Frame-Options HTTP response header field and frame-busting
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patterns (see [CSP-2] for details). Level 2 of this standard patterns (see [CSP-2] for details). Level 2 of this standard
provides a robust mechanism for protecting against clickjacking by provides a robust mechanism for protecting against clickjacking by
using policies that restrict the origin of frames (using "frame- using policies that restrict the origin of frames (using "frame-
ancestors") together with those that restrict the sources of scripts ancestors") together with those that restrict the sources of scripts
allowed to execute on an HTML page (by using "script-src"). A non- allowed to execute on an HTML page (by using "script-src"). A non-
normative example of such a policy is shown in the following listing: normative example of such a policy is shown in the following listing:
"HTTP/1.1 200 OK Content-Security-Policy: frame-ancestors "HTTP/1.1 200 OK Content-Security-Policy: frame-ancestors
https://ext.example.org:8000 Content-Security-Policy: script-src https://ext.example.org:8000 Content-Security-Policy: script-src
'self' X-Frame-Options: ALLOW-FROM https://ext.example.org:8000 ..." 'self' X-Frame-Options: ALLOW-FROM https://ext.example.org:8000 ..."
Because some user agents do not support [CSP-2], this technique Because some user agents do not support [CSP-2], this technique
SHOULD be combined with others, including those described in SHOULD be combined with others, including those described in
[RFC6819], unless such legacy user agents are explicitly unsupported [RFC6819], unless such legacy user agents are explicitly unsupported
by the authorization server. Even in such cases, additional by the authorization server. Even in such cases, additional
countermeasures SHOULD still be employed. countermeasures SHOULD still be employed.
9.17. Code Injection and Input Validation 7.17. Code Injection and Input Validation
A code injection attack occurs when an input or otherwise external A code injection attack occurs when an input or otherwise external
variable is used by an application unsanitized and causes variable is used by an application unsanitized and causes
modification to the application logic. This may allow an attacker to modification to the application logic. This may allow an attacker to
gain access to the application device or its data, cause denial of gain access to the application device or its data, cause denial of
service, or introduce a wide range of malicious side-effects. service, or introduce a wide range of malicious side-effects.
The authorization server and client MUST sanitize (and validate when The authorization server and client MUST sanitize (and validate when
possible) any value received - in particular, the value of the possible) any value received - in particular, the value of the
"state" and "redirect_uri" parameters. "state" and "redirect_uri" parameters.
9.18. Open Redirectors 7.18. Open Redirectors
The following attacks can occur when an AS or client has an open The following attacks can occur when an AS or client has an open
redirector. An open redirector is an endpoint that forwards a user's redirector. An open redirector is an endpoint that forwards a user's
browser to an arbitrary URI obtained from a query parameter. browser to an arbitrary URI obtained from a query parameter.
9.18.1. Client as Open Redirector 7.18.1. Client as Open Redirector
Clients MUST NOT expose open redirectors. Attackers may use open Clients MUST NOT expose open redirectors. Attackers may use open
redirectors to produce URLs pointing to the client and utilize them redirectors to produce URLs pointing to the client and utilize them
to exfiltrate authorization codes and access tokens, as described in to exfiltrate authorization codes and access tokens, as described in
(#redir_uri_open_redir). Another abuse case is to produce URLs that (#redir_uri_open_redir). Another abuse case is to produce URLs that
appear to point to the client. This might trick users into trusting appear to point to the client. This might trick users into trusting
the URL and follow it in their browser. This can be abused for the URL and follow it in their browser. This can be abused for
phishing. phishing.
In order to prevent open redirection, clients should only redirect if In order to prevent open redirection, clients should only redirect if
the target URLs are whitelisted or if the origin and integrity of a the target URLs are whitelisted or if the origin and integrity of a
request can be authenticated. Countermeasures against open request can be authenticated. Countermeasures against open
redirection are described by OWASP [owasp_redir]. redirection are described by OWASP [owasp_redir].
9.18.2. Authorization Server as Open Redirector 7.18.2. Authorization Server as Open Redirector
Just as with clients, attackers could try to utilize a user's trust Just as with clients, attackers could try to utilize a user's trust
in the authorization server (and its URL in particular) for in the authorization server (and its URL in particular) for
performing phishing attacks. OAuth authorization servers regularly performing phishing attacks. OAuth authorization servers regularly
redirect users to other web sites (the clients), but must do so in a redirect users to other web sites (the clients), but must do so in a
safe way. safe way.
Section 4.1.2.1 already prevents open redirects by stating that the Section 4.1.2.1 already prevents open redirects by stating that the
AS MUST NOT automatically redirect the user agent in case of an AS MUST NOT automatically redirect the user agent in case of an
invalid combination of "client_id" and "redirect_uri". invalid combination of "client_id" and "redirect_uri".
skipping to change at page 67, line 22 skipping to change at page 67, line 14
and intentionally send an erroneous authorization request, e.g., by and intentionally send an erroneous authorization request, e.g., by
using an invalid scope value, thus instructing the AS to redirect the using an invalid scope value, thus instructing the AS to redirect the
user agent to its phishing site. user agent to its phishing site.
The AS MUST take precautions to prevent this threat. Based on its The AS MUST take precautions to prevent this threat. Based on its
risk assessment, the AS needs to decide whether it can trust the risk assessment, the AS needs to decide whether it can trust the
redirect URI and SHOULD only automatically redirect the user agent if redirect URI and SHOULD only automatically redirect the user agent if
it trusts the redirect URI. If the URI is not trusted, the AS MAY it trusts the redirect URI. If the URI is not trusted, the AS MAY
inform the user and rely on the user to make the correct decision. inform the user and rely on the user to make the correct decision.
9.19. Authorization Server Mix-Up Mitigation in Native Apps 7.19. Authorization Server Mix-Up Mitigation in Native Apps
(TODO: merge this with the regular mix-up section when it is brought (TODO: merge this with the regular mix-up section when it is brought
in) in)
To protect against a compromised or malicious authorization server To protect against a compromised or malicious authorization server
attacking another authorization server used by the same app, it is attacking another authorization server used by the same app, it is
REQUIRED that a unique redirect URI is used for each authorization REQUIRED that a unique redirect URI is used for each authorization
server used by the app (for example, by varying the path component), server used by the app (for example, by varying the path component),
and that authorization responses are rejected if the redirect URI and that authorization responses are rejected if the redirect URI
they were received on doesn't match the redirect URI in an outgoing they were received on doesn't match the redirect URI in an outgoing
authorization request. authorization request.
The native app MUST store the redirect URI used in the authorization The native app MUST store the redirect URI used in the authorization
request with the authorization session data (i.e., along with "state" request with the authorization session data (i.e., along with "state"
and other related data) and MUST verify that the URI on which the and other related data) and MUST verify that the URI on which the
authorization response was received exactly matches it. authorization response was received exactly matches it.
The requirement of Section 9.2, specifically that authorization The requirement of Section 7.3, specifically that authorization
servers reject requests with URIs that don't match what was servers reject requests with URIs that don't match what was
registered, is also required to prevent such attacks. registered, is also required to prevent such attacks.
9.20. Embedded User Agents in Native Apps 7.20. Embedded User Agents in Native Apps
Embedded user-agents are a technically possible method for Embedded user agents are a technically possible method for
authorizing native apps. These embedded user-agents are unsafe for authorizing native apps. These embedded user agents are unsafe for
use by third parties to the authorization server by definition, as use by third parties to the authorization server by definition, as
the app that hosts the embedded user-agent can access the user's full the app that hosts the embedded user agent can access the user's full
authentication credential, not just the OAuth authorization grant authentication credential, not just the OAuth authorization grant
that was intended for the app. that was intended for the app.
In typical web-view-based implementations of embedded user-agents, In typical web-view-based implementations of embedded user agents,
the host application can record every keystroke entered in the login the host application can record every keystroke entered in the login
form to capture usernames and passwords, automatically submit forms form to capture usernames and passwords, automatically submit forms
to bypass user consent, and copy session cookies and use them to to bypass user consent, and copy session cookies and use them to
perform authenticated actions as the user. perform authenticated actions as the user.
Even when used by trusted apps belonging to the same party as the Even when used by trusted apps belonging to the same party as the
authorization server, embedded user-agents violate the principle of authorization server, embedded user agents violate the principle of
least privilege by having access to more powerful credentials than least privilege by having access to more powerful credentials than
they need, potentially increasing the attack surface. they need, potentially increasing the attack surface.
Encouraging users to enter credentials in an embedded user-agent Encouraging users to enter credentials in an embedded user agent
without the usual address bar and visible certificate validation without the usual address bar and visible certificate validation
features that browsers have makes it impossible for the user to know features that browsers have makes it impossible for the user to know
if they are signing in to the legitimate site; even when they are, it if they are signing in to the legitimate site; even when they are, it
trains them that it's OK to enter credentials without validating the trains them that it's OK to enter credentials without validating the
site first. site first.
Aside from the security concerns, embedded user-agents do not share Aside from the security concerns, embedded user agents do not share
the authentication state with other apps or the browser, requiring the authentication state with other apps or the browser, requiring
the user to log in for every authorization request, which is often the user to log in for every authorization request, which is often
considered an inferior user experience. considered an inferior user experience.
9.21. Other Recommendations 7.21. Other Recommendations
Authorization servers SHOULD NOT allow clients to influence their Authorization servers SHOULD NOT allow clients to influence their
"client_id" or "sub" value or any other claim if that can cause "client_id" or "sub" value or any other claim if that can cause
confusion with a genuine resource owner (see confusion with a genuine resource owner (see
(#client_impersonating)). (#client_impersonating)).
10. Native Applications 8. Native Applications
Native applications are clients installed and executed on the device Native applications are clients installed and executed on the device
used by the resource owner (i.e., desktop application, native mobile used by the resource owner (i.e., desktop application, native mobile
application). Native applications require special consideration application). Native applications require special consideration
related to security, platform capabilities, and overall end-user related to security, platform capabilities, and overall end-user
experience. experience.
The authorization endpoint requires interaction between the client The authorization endpoint requires interaction between the client
and the resource owner's user-agent. The best current practice is to and the resource owner's user agent. The best current practice is to
perform the OAuth authorization request in an external user-agent perform the OAuth authorization request in an external user agent
(typically the browser) rather than an embedded user-agent (such as (typically the browser) rather than an embedded user agent (such as
one implemented with web-views). one implemented with web-views).
The native application can capture the response from the The native application can capture the response from the
authorization server using a redirect URI with a scheme registered authorization server using a redirect URI with a scheme registered
with the operating system to invoke the client as the handler, manual with the operating system to invoke the client as the handler, manual
copy-and-paste of the credentials, running a local web server, copy-and-paste of the credentials, running a local web server,
installing a user-agent extension, or by providing a redirect URI installing a user agent extension, or by providing a redirect URI
identifying a server-hosted resource under the client's control, identifying a server-hosted resource under the client's control,
which in turn makes the response available to the native application. which in turn makes the response available to the native application.
Previously, it was common for native apps to use embedded user-agents Previously, it was common for native apps to use embedded user agents
(commonly implemented with web-views) for OAuth authorization (commonly implemented with web-views) for OAuth authorization
requests. That approach has many drawbacks, including the host app requests. That approach has many drawbacks, including the host app
being able to copy user credentials and cookies as well as the user being able to copy user credentials and cookies as well as the user
needing to authenticate from scratch in each app. See Section 9.20 needing to authenticate from scratch in each app. See Section 7.20
for a deeper analysis of the drawbacks of using embedded user-agents for a deeper analysis of the drawbacks of using embedded user agents
for OAuth. for OAuth.
Native app authorization requests that use the browser are more Native app authorization requests that use the browser are more
secure and can take advantage of the user's authentication state. secure and can take advantage of the user's authentication state.
Being able to use the existing authentication session in the browser Being able to use the existing authentication session in the browser
enables single sign-on, as users don't need to authenticate to the enables single sign-on, as users don't need to authenticate to the
authorization server each time they use a new app (unless required by authorization server each time they use a new app (unless required by
the authorization server policy). the authorization server policy).
Supporting authorization flows between a native app and the browser Supporting authorization flows between a native app and the browser
is possible without changing the OAuth protocol itself, as the OAuth is possible without changing the OAuth protocol itself, as the OAuth
authorization request and response are already defined in terms of authorization request and response are already defined in terms of
URIs. This encompasses URIs that can be used for inter-app URIs. This encompasses URIs that can be used for inter-app
communication. Some OAuth server implementations that assume all communication. Some OAuth server implementations that assume all
clients are confidential web clients will need to add an clients are confidential web clients will need to add an
understanding of public native app clients and the types of redirect understanding of public native app clients and the types of redirect
URIs they use to support this best practice. URIs they use to support this best practice.
10.1. Using Inter-App URI Communication for OAuth in Native Apps 8.1. Using Inter-App URI Communication for OAuth in Native Apps
Just as URIs are used for OAuth on the web to initiate the Just as URIs are used for OAuth on the web to initiate the
authorization request and return the authorization response to the authorization request and return the authorization response to the
requesting website, URIs can be used by native apps to initiate the requesting website, URIs can be used by native apps to initiate the
authorization request in the device's browser and return the response authorization request in the device's browser and return the response
to the requesting native app. to the requesting native app.
By adopting the same methods used on the web for OAuth, benefits seen By adopting the same methods used on the web for OAuth, benefits seen
in the web context like the usability of a single sign-on session and in the web context like the usability of a single sign-on session and
the security of a separate authentication context are likewise gained the security of a separate authentication context are likewise gained
in the native app context. Reusing the same approach also reduces in the native app context. Reusing the same approach also reduces
the implementation complexity and increases interoperability by the implementation complexity and increases interoperability by
relying on standards-based web flows that are not specific to a relying on standards-based web flows that are not specific to a
particular platform. particular platform.
Native apps MUST use an external user-agent to perform OAuth Native apps MUST use an external user agent to perform OAuth
authorization requests. This is achieved by opening the authorization requests. This is achieved by opening the
authorization request in the browser (detailed in Section 10.2) and authorization request in the browser (detailed in Section 8.2) and
using a redirect URI that will return the authorization response back using a redirect URI that will return the authorization response back
to the native app (defined in Section 10.3). to the native app (defined in Section 8.3).
10.2. Initiating the Authorization Request from a Native App 8.2. Initiating the Authorization Request from a Native App
Native apps needing user authorization create an authorization Native apps needing user authorization create an authorization
request URI with the authorization code grant type per Section 4.1 request URI with the authorization code grant type per Section 4.1
using a redirect URI capable of being received by the native app. using a redirect URI capable of being received by the native app.
The function of the redirect URI for a native app authorization The function of the redirect URI for a native app authorization
request is similar to that of a web-based authorization request. request is similar to that of a web-based authorization request.
Rather than returning the authorization response to the OAuth Rather than returning the authorization response to the OAuth
client's server, the redirect URI used by a native app returns the client's server, the redirect URI used by a native app returns the
response to the app. Several options for a redirect URI that will response to the app. Several options for a redirect URI that will
return the authorization response to the native app in different return the authorization response to the native app in different
platforms are documented in Section 10.3. Any redirect URI that platforms are documented in Section 8.3. Any redirect URI that
allows the app to receive the URI and inspect its parameters is allows the app to receive the URI and inspect its parameters is
viable. viable.
After constructing the authorization request URI, the app uses After constructing the authorization request URI, the app uses
platform-specific APIs to open the URI in an external user-agent. platform-specific APIs to open the URI in an external user agent.
Typically, the external user-agent used is the default browser, that Typically, the external user agent used is the default browser, that
is, the application configured for handling "http" and "https" scheme is, the application configured for handling "http" and "https" scheme
URIs on the system; however, different browser selection criteria and URIs on the system; however, different browser selection criteria and
other categories of external user-agents MAY be used. other categories of external user agents MAY be used.
This best practice focuses on the browser as the RECOMMENDED external This best practice focuses on the browser as the RECOMMENDED external
user-agent for native apps. An external user-agent designed user agent for native apps. An external user agent designed
specifically for user authorization and capable of processing specifically for user authorization and capable of processing
authorization requests and responses like a browser MAY also be used. authorization requests and responses like a browser MAY also be used.
Other external user-agents, such as a native app provided by the Other external user agents, such as a native app provided by the
authorization server may meet the criteria set out in this best authorization server may meet the criteria set out in this best
practice, including using the same redirect URI properties, but their practice, including using the same redirect URI properties, but their
use is out of scope for this specification. use is out of scope for this specification.
Some platforms support a browser feature known as "in-app browser Some platforms support a browser feature known as "in-app browser
tabs", where an app can present a tab of the browser within the app tabs", where an app can present a tab of the browser within the app
context without switching apps, but still retain key benefits of the context without switching apps, but still retain key benefits of the
browser such as a shared authentication state and security context. browser such as a shared authentication state and security context.
On platforms where they are supported, it is RECOMMENDED, for On platforms where they are supported, it is RECOMMENDED, for
usability reasons, that apps use in-app browser tabs for the usability reasons, that apps use in-app browser tabs for the
authorization request. authorization request.
10.3. Receiving the Authorization Response in a Native App 8.3. Receiving the Authorization Response in a Native App
There are several redirect URI options available to native apps for There are several redirect URI options available to native apps for
receiving the authorization response from the browser, the receiving the authorization response from the browser, the
availability and user experience of which varies by platform. availability and user experience of which varies by platform.
To fully support native apps, authorization servers MUST offer at To fully support native apps, authorization servers MUST offer at
least the three redirect URI options described in the following least the three redirect URI options described in the following
subsections to native apps. Native apps MAY use whichever redirect subsections to native apps. Native apps MAY use whichever redirect
option suits their needs best, taking into account platform-specific option suits their needs best, taking into account platform-specific
implementation details. implementation details.
10.3.1. Private-Use URI Scheme Redirection 8.3.1. Private-Use URI Scheme Redirection
Many mobile and desktop computing platforms support inter-app Many mobile and desktop computing platforms support inter-app
communication via URIs by allowing apps to register private-use URI communication via URIs by allowing apps to register private-use URI
schemes (sometimes colloquially referred to as "custom URL schemes") schemes (sometimes colloquially referred to as "custom URL schemes")
like "com.example.app". When the browser or another app attempts to like "com.example.app". When the browser or another app attempts to
load a URI with a private-use URI scheme, the app that registered it load a URI with a private-use URI scheme, the app that registered it
is launched to handle the request. is launched to handle the request.
To perform an authorization request with a private-use URI scheme To perform an authorization request with a private-use URI scheme
redirect, the native app launches the browser with a standard redirect, the native app launches the browser with a standard
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that use app identifiers based on reverse-order domain names, those that use app identifiers based on reverse-order domain names, those
identifiers can be reused as the private-use URI scheme for the OAuth identifiers can be reused as the private-use URI scheme for the OAuth
redirect to help avoid this problem. redirect to help avoid this problem.
Following the requirements of Section 3.2 of [RFC3986], as there is Following the requirements of Section 3.2 of [RFC3986], as there is
no naming authority for private-use URI scheme redirects, only a no naming authority for private-use URI scheme redirects, only a
single slash ("/") appears after the scheme component. A complete single slash ("/") appears after the scheme component. A complete
example of a redirect URI utilizing a private-use URI scheme is: example of a redirect URI utilizing a private-use URI scheme is:
com.example.app:/oauth2redirect/example-provider com.example.app:/oauth2redirect/example-provider
When the authorization server completes the request, it redirects to When the authorization server completes the request, it redirects to
the client's redirect URI as it would normally. As the redirect URI the client's redirect URI as it would normally. As the redirect URI
uses a private-use URI scheme, it results in the operating system uses a private-use URI scheme, it results in the operating system
launching the native app, passing in the URI as a launch parameter. launching the native app, passing in the URI as a launch parameter.
Then, the native app uses normal processing for the authorization Then, the native app uses normal processing for the authorization
response. response.
10.3.2. Claimed "https" Scheme URI Redirection 8.3.2. Claimed "https" Scheme URI Redirection
Some operating systems allow apps to claim "https" scheme [RFC7230] Some operating systems allow apps to claim "https" scheme [RFC7230]
URIs in the domains they control. When the browser encounters a URIs in the domains they control. When the browser encounters a
claimed URI, instead of the page being loaded in the browser, the claimed URI, instead of the page being loaded in the browser, the
native app is launched with the URI supplied as a launch parameter. native app is launched with the URI supplied as a launch parameter.
Such URIs can be used as redirect URIs by native apps. They are Such URIs can be used as redirect URIs by native apps. They are
indistinguishable to the authorization server from a regular web- indistinguishable to the authorization server from a regular web-
based client redirect URI. An example is: based client redirect URI. An example is:
https://app.example.com/oauth2redirect/example-provider https://app.example.com/oauth2redirect/example-provider
As the redirect URI alone is not enough to distinguish public native As the redirect URI alone is not enough to distinguish public native
app clients from confidential web clients, it is REQUIRED in app clients from confidential web clients, it is REQUIRED in
Section 9.2 that the client type be recorded during client Section 7.3 that the client type be recorded during client
registration to enable the server to determine the client type and registration to enable the server to determine the client type and
act accordingly. act accordingly.
App-claimed "https" scheme redirect URIs have some advantages App-claimed "https" scheme redirect URIs have some advantages
compared to other native app redirect options in that the identity of compared to other native app redirect options in that the identity of
the destination app is guaranteed to the authorization server by the the destination app is guaranteed to the authorization server by the
operating system. For this reason, native apps SHOULD use them over operating system. For this reason, native apps SHOULD use them over
the other options where possible. the other options where possible.
10.3.3. Loopback Interface Redirection 8.3.3. Loopback Interface Redirection
Native apps that are able to open a port on the loopback network Native apps that are able to open a port on the loopback network
interface without needing special permissions (typically, those on interface without needing special permissions (typically, those on
desktop operating systems) can use the loopback interface to receive desktop operating systems) can use the loopback interface to receive
the OAuth redirect. the OAuth redirect.
Loopback redirect URIs use the "http" scheme and are constructed with Loopback redirect URIs use the "http" scheme and are constructed with
the loopback IP literal and whatever port the client is listening on. the loopback IP literal and whatever port the client is listening on.
That is, "http://127.0.0.1:{port}/{path}" for IPv4, and That is, "http://127.0.0.1:{port}/{path}" for IPv4, and
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The authorization server MUST allow any port to be specified at the The authorization server MUST allow any port to be specified at the
time of the request for loopback IP redirect URIs, to accommodate time of the request for loopback IP redirect URIs, to accommodate
clients that obtain an available ephemeral port from the operating clients that obtain an available ephemeral port from the operating
system at the time of the request. system at the time of the request.
Clients SHOULD NOT assume that the device supports a particular Clients SHOULD NOT assume that the device supports a particular
version of the Internet Protocol. It is RECOMMENDED that clients version of the Internet Protocol. It is RECOMMENDED that clients
attempt to bind to the loopback interface using both IPv4 and IPv6 attempt to bind to the loopback interface using both IPv4 and IPv6
and use whichever is available. and use whichever is available.
11. Browser-Based Apps 9. Browser-Based Apps
Browser-based apps are are clients that run in a web browser, Browser-based apps are are clients that run in a web browser,
typically written in JavaScript, also known as "single-page apps". typically written in JavaScript, also known as "single-page apps".
These types of apps have particular security considerations similar These types of apps have particular security considerations similar
to native apps. to native apps.
TODO: Bring in the normative text of the browser-based apps BCP when TODO: Bring in the normative text of the browser-based apps BCP when
it is finalized. it is finalized.
12. Differences from OAuth 2.0 10. Differences from OAuth 2.0
This draft consolidates the functionality in OAuth 2.0 [RFC6749], This draft consolidates the functionality in OAuth 2.0 [RFC6749],
OAuth 2.0 for Native Apps ([RFC8252]), Proof Key for Code Exchange OAuth 2.0 for Native Apps ([RFC8252]), Proof Key for Code Exchange
([RFC7636]), OAuth 2.0 for Browser-Based Apps ([RFC7636]), OAuth 2.0 for Browser-Based Apps
([I-D.ietf-oauth-browser-based-apps]), OAuth Security Best Current ([I-D.ietf-oauth-browser-based-apps]), OAuth Security Best Current
Practice ([I-D.ietf-oauth-security-topics]), and Bearer Token Usage Practice ([I-D.ietf-oauth-security-topics]), and Bearer Token Usage
([RFC6750]). ([RFC6750]).
Where a later draft updates or obsoletes functionality found in the Where a later draft updates or obsoletes functionality found in the
original [RFC6749], that functionality in this draft is updated with original [RFC6749], that functionality in this draft is updated with
skipping to change at page 74, line 28 skipping to change at page 74, line 20
specification as per Section 2.4 of specification as per Section 2.4 of
[I-D.ietf-oauth-security-topics] [I-D.ietf-oauth-security-topics]
* Bearer token usage omits the use of bearer tokens in the query * Bearer token usage omits the use of bearer tokens in the query
string of URIs as per Section 4.3.2 of string of URIs as per Section 4.3.2 of
[I-D.ietf-oauth-security-topics] [I-D.ietf-oauth-security-topics]
* Refresh tokens should either be sender-constrained or one-time use * Refresh tokens should either be sender-constrained or one-time use
as per Section 4.12.2 of [I-D.ietf-oauth-security-topics] as per Section 4.12.2 of [I-D.ietf-oauth-security-topics]
13. IANA Considerations 11. IANA Considerations
This document does not require any IANA actions. This document does not require any IANA actions.
All referenced registries are defined by RFC6749 and related All referenced registries are defined by [RFC6749] and related
documents that this work is based upon. No changes to those documents that this work is based upon. No changes to those
registries are required by this specification. registries are required by this specification.
14. References 12. References
14.1. Normative References 12.1. Normative References
[BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre, [BCP195] Saint-Andre, P., "Recommendations for Secure Use of
"Recommendations for Secure Use of Transport Layer Transport Layer Security (TLS)", 2015.
Security (TLS)", n.d..
[I-D.ietf-oauth-security-topics] [I-D.ietf-oauth-security-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-16, 5 October 2020, <http://www.ietf.org/internet- topics-18, 13 April 2021,
drafts/draft-ietf-oauth-security-topics-16.txt>. <https://www.ietf.org/archive/id/draft-ietf-oauth-
security-topics-18.txt>.
[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/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication", Authentication: Basic and Digest Access Authentication",
RFC 2617, DOI 10.17487/RFC2617, June 1999, RFC 2617, DOI 10.17487/RFC2617, June 1999,
skipping to change at page 76, line 18 skipping to change at page 76, line 5
[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/info/rfc6750>. <https://www.rfc-editor.org/info/rfc6750>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>. 2014, <https://www.rfc-editor.org/info/rfc7159>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014, DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>. <https://www.rfc-editor.org/info/rfc7231>.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
RFC 7234, DOI 10.17487/RFC7234, June 2014, RFC 7234, DOI 10.17487/RFC7234, June 2014,
<https://www.rfc-editor.org/info/rfc7234>. <https://www.rfc-editor.org/info/rfc7234>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/info/rfc7235>.
[RFC7595] Thaler, D., Ed., Hansen, T., and T. Hardie, "Guidelines [RFC7595] Thaler, D., Ed., Hansen, T., and T. Hardie, "Guidelines
and Registration Procedures for URI Schemes", BCP 35, and Registration Procedures for URI Schemes", BCP 35,
RFC 7595, DOI 10.17487/RFC7595, June 2015, RFC 7595, DOI 10.17487/RFC7595, June 2015,
<https://www.rfc-editor.org/info/rfc7595>. <https://www.rfc-editor.org/info/rfc7595>.
[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/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8252] Denniss, W. and J. Bradley, "OAuth 2.0 for Native Apps", [RFC8252] Denniss, W. and J. Bradley, "OAuth 2.0 for Native Apps",
skipping to change at page 77, line 18 skipping to change at page 77, line 12
REC-html401-19991224, 24 December 1999, REC-html401-19991224, 24 December 1999,
<https://www.w3.org/TR/1999/REC-html401-19991224>. <https://www.w3.org/TR/1999/REC-html401-19991224>.
[W3C.REC-xml-20081126] [W3C.REC-xml-20081126]
Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
Edition)", World Wide Web Consortium Recommendation REC- Edition)", World Wide Web Consortium Recommendation REC-
xml-20081126, 26 November 2008, xml-20081126, 26 November 2008,
<https://www.w3.org/TR/2008/REC-xml-20081126>. <https://www.w3.org/TR/2008/REC-xml-20081126>.
14.2. Informative References 12.2. Informative References
[CSP-2] "Content Security Policy Level 2", December 2016, [CSP-2] "Content Security Policy Level 2", December 2016,
<https://www.w3.org/TR/CSP2>. <https://www.w3.org/TR/CSP2>.
[I-D.bradley-oauth-jwt-encoded-state] [I-D.bradley-oauth-jwt-encoded-state]
Bradley, J., Lodderstedt, T., and H. Zandbelt, "Encoding Bradley, J., Lodderstedt, D. T., and H. Zandbelt,
claims in the OAuth 2 state parameter using a JWT", Work "Encoding claims in the OAuth 2 state parameter using a
in Progress, Internet-Draft, draft-bradley-oauth-jwt- JWT", Work in Progress, Internet-Draft, draft-bradley-
encoded-state-09, 4 November 2018, <http://www.ietf.org/ oauth-jwt-encoded-state-09, 4 November 2018,
internet-drafts/draft-bradley-oauth-jwt-encoded-state- <https://www.ietf.org/archive/id/draft-bradley-oauth-jwt-
09.txt>. encoded-state-09.txt>.
[I-D.ietf-oauth-access-token-jwt] [I-D.ietf-oauth-access-token-jwt]
Bertocci, V., "JSON Web Token (JWT) Profile for OAuth 2.0 Bertocci, V., "JSON Web Token (JWT) Profile for OAuth 2.0
Access Tokens", Work in Progress, Internet-Draft, draft- Access Tokens", Work in Progress, Internet-Draft, draft-
ietf-oauth-access-token-jwt-11, 22 January 2021, ietf-oauth-access-token-jwt-13, 25 May 2021,
<http://www.ietf.org/internet-drafts/draft-ietf-oauth- <https://www.ietf.org/archive/id/draft-ietf-oauth-access-
access-token-jwt-11.txt>. token-jwt-13.txt>.
[I-D.ietf-oauth-browser-based-apps] [I-D.ietf-oauth-browser-based-apps]
Parecki, A. and D. Waite, "OAuth 2.0 for Browser-Based Parecki, A. and D. Waite, "OAuth 2.0 for Browser-Based
Apps", Work in Progress, Internet-Draft, draft-ietf-oauth- Apps", Work in Progress, Internet-Draft, draft-ietf-oauth-
browser-based-apps-07, 2 October 2020, browser-based-apps-08, 17 May 2021,
<http://www.ietf.org/internet-drafts/draft-ietf-oauth- <https://www.ietf.org/archive/id/draft-ietf-oauth-browser-
browser-based-apps-07.txt>. based-apps-08.txt>.
[I-D.ietf-oauth-dpop] [I-D.ietf-oauth-dpop]
Fett, D., Campbell, B., Bradley, J., Lodderstedt, T., Fett, D., Campbell, B., Bradley, J., Lodderstedt, T.,
Jones, M., and D. Waite, "OAuth 2.0 Demonstrating Proof- Jones, M., and D. Waite, "OAuth 2.0 Demonstrating Proof-
of-Possession at the Application Layer (DPoP)", Work in of-Possession at the Application Layer (DPoP)", Work in
Progress, Internet-Draft, draft-ietf-oauth-dpop-02, 18 Progress, Internet-Draft, draft-ietf-oauth-dpop-03, 7
November 2020, <http://www.ietf.org/internet-drafts/draft- April 2021, <https://www.ietf.org/archive/id/draft-ietf-
ietf-oauth-dpop-02.txt>. oauth-dpop-03.txt>.
[I-D.ietf-oauth-par] [I-D.ietf-oauth-par]
Lodderstedt, T., Campbell, B., Sakimura, N., Tonge, D., Lodderstedt, T., Campbell, B., Sakimura, N., Tonge, D.,
and F. Skokan, "OAuth 2.0 Pushed Authorization Requests", and F. Skokan, "OAuth 2.0 Pushed Authorization Requests",
Work in Progress, Internet-Draft, draft-ietf-oauth-par-05, Work in Progress, Internet-Draft, draft-ietf-oauth-par-10,
14 December 2020, <http://www.ietf.org/internet-drafts/ 29 July 2021, <https://www.ietf.org/archive/id/draft-ietf-
draft-ietf-oauth-par-05.txt>. oauth-par-10.txt>.
[I-D.ietf-oauth-rar] [I-D.ietf-oauth-rar]
Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0 Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0
Rich Authorization Requests", Work in Progress, Internet- Rich Authorization Requests", Work in Progress, Internet-
Draft, draft-ietf-oauth-rar-03, 18 October 2020, Draft, draft-ietf-oauth-rar-05, 15 May 2021,
<http://www.ietf.org/internet-drafts/draft-ietf-oauth-rar- <https://www.ietf.org/archive/id/draft-ietf-oauth-rar-
03.txt>. 05.txt>.
[I-D.ietf-oauth-token-binding] [I-D.ietf-oauth-token-binding]
Jones, M., Campbell, B., Bradley, J., and W. Denniss, Jones, M. B., Campbell, B., Bradley, J., and W. Denniss,
"OAuth 2.0 Token Binding", Work in Progress, Internet- "OAuth 2.0 Token Binding", Work in Progress, Internet-
Draft, draft-ietf-oauth-token-binding-08, 19 October 2018, Draft, draft-ietf-oauth-token-binding-08, 19 October 2018,
<http://www.ietf.org/internet-drafts/draft-ietf-oauth- <https://www.ietf.org/archive/id/draft-ietf-oauth-token-
token-binding-08.txt>. binding-08.txt>.
[NIST800-63] [NIST800-63]
Burr, W., Dodson, D., Newton, E., Perlner, R., Polk, T., Burr, W., Dodson, D., Newton, E., Perlner, R., Polk, T.,
Gupta, S., and E. Nabbus, "NIST Special Publication Gupta, S., and E. Nabbus, "NIST Special Publication
800-63-1, INFORMATION SECURITY", December 2011, 800-63-1, INFORMATION SECURITY", December 2011,
<http://csrc.nist.gov/publications/>. <http://csrc.nist.gov/publications/>.
[OMAP] Huff, J., Schlacht, D., Nadalin, A., Simmons, J., [OMAP] Huff, J., Schlacht, D., Nadalin, A., Simmons, J.,
Rosenberg, P., Madsen, P., Ace, T., Rickelton-Abdi, C., Rosenberg, P., Madsen, P., Ace, T., Rickelton-Abdi, C.,
and B. Boyer, "Online Multimedia Authorization Protocol: and B. Boyer, "Online Multimedia Authorization Protocol:
skipping to change at page 79, line 24 skipping to change at page 79, line 14
[RFC6819] Lodderstedt, T., Ed., McGloin, M., and P. Hunt, "OAuth 2.0 [RFC6819] Lodderstedt, T., Ed., McGloin, M., and P. Hunt, "OAuth 2.0
Threat Model and Security Considerations", RFC 6819, Threat Model and Security Considerations", RFC 6819,
DOI 10.17487/RFC6819, January 2013, DOI 10.17487/RFC6819, January 2013,
<https://www.rfc-editor.org/info/rfc6819>. <https://www.rfc-editor.org/info/rfc6819>.
[RFC7009] Lodderstedt, T., Ed., Dronia, S., and M. Scurtescu, "OAuth [RFC7009] Lodderstedt, T., Ed., Dronia, S., and M. Scurtescu, "OAuth
2.0 Token Revocation", RFC 7009, DOI 10.17487/RFC7009, 2.0 Token Revocation", RFC 7009, DOI 10.17487/RFC7009,
August 2013, <https://www.rfc-editor.org/info/rfc7009>. August 2013, <https://www.rfc-editor.org/info/rfc7009>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/info/rfc7235>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>. <https://www.rfc-editor.org/info/rfc7519>.
[RFC7591] Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and [RFC7591] Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and
P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol", P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
RFC 7591, DOI 10.17487/RFC7591, July 2015, RFC 7591, DOI 10.17487/RFC7591, July 2015,
<https://www.rfc-editor.org/info/rfc7591>. <https://www.rfc-editor.org/info/rfc7591>.
[RFC7592] Richer, J., Ed., Jones, M., Bradley, J., and M. Machulak, [RFC7592] Richer, J., Ed., Jones, M., Bradley, J., and M. Machulak,
skipping to change at page 81, line 7 skipping to change at page 80, line 34
NQSCHAR = %x20-21 / %x23-5B / %x5D-7E NQSCHAR = %x20-21 / %x23-5B / %x5D-7E
UNICODECHARNOCRLF = %x09 /%x20-7E / %x80-D7FF / UNICODECHARNOCRLF = %x09 /%x20-7E / %x80-D7FF /
%xE000-FFFD / %x10000-10FFFF %xE000-FFFD / %x10000-10FFFF
(The UNICODECHARNOCRLF definition is based upon the Char definition (The UNICODECHARNOCRLF definition is based upon the Char definition
in Section 2.2 of [W3C.REC-xml-20081126], but omitting the Carriage in Section 2.2 of [W3C.REC-xml-20081126], but omitting the Carriage
Return and Linefeed characters.) Return and Linefeed characters.)
A.1. "client_id" Syntax A.1. "client_id" Syntax
The "client_id" element is defined in Section 2.3.1: The "client_id" element is defined in Section 2.4.1:
client-id = *VSCHAR client-id = *VSCHAR
A.2. "client_secret" Syntax A.2. "client_secret" Syntax
The "client_secret" element is defined in Section 2.3.1: The "client_secret" element is defined in Section 2.4.1:
client-secret = *VSCHAR client-secret = *VSCHAR
A.3. "response_type" Syntax A.3. "response_type" Syntax
The "response_type" element is defined in Section 3.1.1 and The "response_type" element is defined in Section 4.1.1 and
Section 8.4: Section 6.4:
response-type = response-name *( SP response-name ) response-type = response-name *( SP response-name )
response-name = 1*response-char response-name = 1*response-char
response-char = "_" / DIGIT / ALPHA response-char = "_" / DIGIT / ALPHA
A.4. "scope" Syntax A.4. "scope" Syntax
The "scope" element is defined in Section 3.3: The "scope" element is defined in Section 3.2.2.1:
scope = scope-token *( SP scope-token ) scope = scope-token *( SP scope-token )
scope-token = 1*NQCHAR scope-token = 1*NQCHAR
A.5. "state" Syntax A.5. "state" Syntax
The "state" element is defined in Section 4.1.1, Section 4.1.2, and The "state" element is defined in Section 4.1.1, Section 4.1.2, and
Section 4.1.2.1: Section 4.1.2.1:
state = 1*VSCHAR state = 1*VSCHAR
skipping to change at page 81, line 50 skipping to change at page 81, line 29
A.6. "redirect_uri" Syntax A.6. "redirect_uri" Syntax
The "redirect_uri" element is defined in Section 4.1.1, and The "redirect_uri" element is defined in Section 4.1.1, and
Section 4.1.3: Section 4.1.3:
redirect-uri = URI-reference redirect-uri = URI-reference
A.7. "error" Syntax A.7. "error" Syntax
The "error" element is defined in Sections Section 4.1.2.1, The "error" element is defined in Sections Section 4.1.2.1,
Section 5.2, 7.2, and 8.5: Section 3.2.3.1, 7.2, and 8.5:
error = 1*NQSCHAR error = 1*NQSCHAR
A.8. "error_description" Syntax A.8. "error_description" Syntax
The "error_description" element is defined in Sections The "error_description" element is defined in Sections
Section 4.1.2.1, Section 5.2, and Section 7.3: Section 4.1.2.1, Section 3.2.3.1, and Section 5.3:
error-description = 1*NQSCHAR error-description = 1*NQSCHAR
A.9. "error_uri" Syntax A.9. "error_uri" Syntax
The "error_uri" element is defined in Sections Section 4.1.2.1, The "error_uri" element is defined in Sections Section 4.1.2.1,
Section 5.2, and 7.2: Section 3.2.3.1, and 7.2:
error-uri = URI-reference error-uri = URI-reference
A.10. "grant_type" Syntax A.10. "grant_type" Syntax
The "grant_type" element is defined in Sections Section 4.1.3, The "grant_type" element is defined in Section Section 3.2.2:
Section 4.2.3, Section 4.2.2, Section 4.3, and Section 6:
grant-type = grant-name / URI-reference grant-type = grant-name / URI-reference
grant-name = 1*name-char grant-name = 1*name-char
name-char = "-" / "." / "_" / DIGIT / ALPHA name-char = "-" / "." / "_" / DIGIT / ALPHA
A.11. "code" Syntax A.11. "code" Syntax
The "code" element is defined in Section 4.1.3: The "code" element is defined in Section 4.1.3:
code = 1*VSCHAR code = 1*VSCHAR
A.12. "access_token" Syntax A.12. "access_token" Syntax
The "access_token" element is defined in Section 4.2.3 and The "access_token" element is defined in Section 3.2.3:
Section 5.1:
access-token = 1*VSCHAR access-token = 1*VSCHAR
A.13. "token_type" Syntax A.13. "token_type" Syntax
The "token_type" element is defined in Section 5.1, and Section 8.1: The "token_type" element is defined in Section 3.2.3, and
Section 6.1:
token-type = type-name / URI-reference token-type = type-name / URI-reference
type-name = 1*name-char type-name = 1*name-char
name-char = "-" / "." / "_" / DIGIT / ALPHA name-char = "-" / "." / "_" / DIGIT / ALPHA
A.14. "expires_in" Syntax A.14. "expires_in" Syntax
The "expires_in" element is defined in Section 5.1: The "expires_in" element is defined in Section 3.2.3:
expires-in = 1*DIGIT expires-in = 1*DIGIT
A.15. "refresh_token" Syntax A.15. "refresh_token" Syntax
The "refresh_token" element is defined in Section 5.1 and Section 6: The "refresh_token" element is defined in Section 3.2.3 and
Section 4.3:
refresh-token = 1*VSCHAR refresh-token = 1*VSCHAR
A.16. Endpoint Parameter Syntax A.16. Endpoint Parameter Syntax
The syntax for new endpoint parameters is defined in Section 8.2: The syntax for new endpoint parameters is defined in Section 6.2:
param-name = 1*name-char param-name = 1*name-char
name-char = "-" / "." / "_" / DIGIT / ALPHA name-char = "-" / "." / "_" / DIGIT / ALPHA
A.17. "code_verifier" Syntax A.17. "code_verifier" Syntax
ABNF for "code_verifier" is as follows. ABNF for "code_verifier" is as follows.
code-verifier = 43*128unreserved code-verifier = 43*128unreserved
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
skipping to change at page 85, line 39 skipping to change at page 85, line 22
resource servers to obtain information about access tokens. resource servers to obtain information about access tokens.
* [RFC7009]: Token Revocation * [RFC7009]: Token Revocation
- The Token Revocation extension defines a mechanism for clients - The Token Revocation extension defines a mechanism for clients
to indicate to the authorization server that an access token is to indicate to the authorization server that an access token is
no longer needed. no longer needed.
* [I-D.ietf-oauth-par]: Pushed Authorization Requests * [I-D.ietf-oauth-par]: Pushed Authorization Requests
- The Pushed Authorization Requsts extension describes a - The Pushed Authorization Requests extension describes a
technique of initiating an OAuth flow from the back channel, technique of initiating an OAuth flow from the back channel,
providing better security and more flexibility for building providing better security and more flexibility for building
complex authorization requests. complex authorization requests.
* [I-D.ietf-oauth-rar]: Rich Authorization Requests * [I-D.ietf-oauth-rar]: Rich Authorization Requests
- Rich Authorization Requests specifies a new parameter - Rich Authorization Requests specifies a new parameter
"authorization_details" that is used to carry fine-grained "authorization_details" that is used to carry fine-grained
authorization data in the OAuth authorization request. authorization data in the OAuth authorization request.
Appendix D. Acknowledgements Appendix D. Acknowledgements
TBD TBD
Appendix E. Document History
[[ To be removed from the final specification ]]
-03
* refactored structure
-02
-01
-00
* initial revision
Authors' Addresses Authors' Addresses
Dick Hardt Dick Hardt
SignIn.Org SignIn.Org
Email: dick.hardt@gmail.com Email: dick.hardt@gmail.com
Aaron Parecki Aaron Parecki
Okta Okta
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