--- 1/draft-ietf-oauth-v2-1-03.txt 2021-10-05 18:13:04.918450660 -0700 +++ 2/draft-ietf-oauth-v2-1-04.txt 2021-10-05 18:13:05.006451766 -0700 @@ -1,21 +1,21 @@ OAuth Working Group D. Hardt -Internet-Draft SignIn.Org +Internet-Draft Hellō Intended status: Standards Track A. Parecki -Expires: 12 March 2022 Okta +Expires: 8 April 2022 Okta T. Lodderstedt yes.com - 8 September 2021 + 5 October 2021 The OAuth 2.1 Authorization Framework - draft-ietf-oauth-v2-1-03 + draft-ietf-oauth-v2-1-04 Abstract The OAuth 2.1 authorization framework enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and an authorization service, or by allowing the third-party application to obtain access on its own behalf. This specification replaces and obsoletes the OAuth 2.0 Authorization Framework described in RFC 6749. @@ -28,21 +28,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on 12 March 2022. + This Internet-Draft will expire on 8 April 2022. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights @@ -63,135 +63,135 @@ 1.4. Access Token . . . . . . . . . . . . . . . . . . . . . . 11 1.5. TLS Version . . . . . . . . . . . . . . . . . . . . . . . 12 1.6. HTTP Redirections . . . . . . . . . . . . . . . . . . . . 12 1.7. Interoperability . . . . . . . . . . . . . . . . . . . . 12 1.8. Compatibility with OAuth 2.0 . . . . . . . . . . . . . . 13 1.9. Notational Conventions . . . . . . . . . . . . . . . . . 13 2. Client Registration . . . . . . . . . . . . . . . . . . . . . 14 2.1. Client Types . . . . . . . . . . . . . . . . . . . . . . 14 2.2. Client Identifier . . . . . . . . . . . . . . . . . . . . 16 2.3. Client Redirection Endpoint . . . . . . . . . . . . . . . 16 - 2.3.1. Endpoint Request Confidentiality . . . . . . . . . . 16 + 2.3.1. Endpoint Request Confidentiality . . . . . . . . . . 17 2.3.2. Registration Requirements . . . . . . . . . . . . . . 17 2.3.3. Multiple Redirect URIs . . . . . . . . . . . . . . . 17 2.3.4. Invalid Endpoint . . . . . . . . . . . . . . . . . . 17 - 2.3.5. Endpoint Content . . . . . . . . . . . . . . . . . . 17 + 2.3.5. Endpoint Content . . . . . . . . . . . . . . . . . . 18 2.4. Client Authentication . . . . . . . . . . . . . . . . . . 18 2.4.1. Client Secret . . . . . . . . . . . . . . . . . . . . 19 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 3.2.2. Token Request . . . . . . . . . . . . . . . . . . . . 22 3.2.3. Token Response . . . . . . . . . . . . . . . . . . . 24 4. Grant Types . . . . . . . . . . . . . . . . . . . . . . . . . 27 4.1. Authorization Code Grant . . . . . . . . . . . . . . . . 28 4.1.1. Authorization Request . . . . . . . . . . . . . . . . 29 4.1.2. Authorization Response . . . . . . . . . . . . . . . 32 4.1.3. Token Endpoint Extension . . . . . . . . . . . . . . 35 4.2. Client Credentials Grant . . . . . . . . . . . . . . . . 36 4.2.1. Token Endpoint Extension . . . . . . . . . . . . . . 37 - 4.3. Refresh Token Grant . . . . . . . . . . . . . . . . . . . 38 - 4.3.1. Token Endpoint Extension . . . . . . . . . . . . . . 38 + 4.3. Refresh Token Grant . . . . . . . . . . . . . . . . . . . 37 + 4.3.1. Token Endpoint Extension . . . . . . . . . . . . . . 37 4.3.2. Refresh Token Response . . . . . . . . . . . . . . . 39 - 4.4. Extension Grants . . . . . . . . . . . . . . . . . . . . 40 - 5. Accessing Protected Resources . . . . . . . . . . . . . . . . 41 - 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 + 4.4. Extension Grants . . . . . . . . . . . . . . . . . . . . 39 + 5. Accessing Protected Resources . . . . . . . . . . . . . . . . 40 + 5.1. Access Token Types . . . . . . . . . . . . . . . . . . . 40 + 5.2. Bearer Tokens . . . . . . . . . . . . . . . . . . . . . . 41 + 5.2.1. Authenticated Requests . . . . . . . . . . . . . . . 41 + 5.2.2. The WWW-Authenticate Response Header Field . . . . . 43 + 5.2.3. Error Codes . . . . . . . . . . . . . . . . . . . . . 44 + 5.3. Error Response . . . . . . . . . . . . . . . . . . . . . 45 + 5.3.1. Extension Token Types . . . . . . . . . . . . . . . . 45 6. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 46 - 6.1. Defining Access Token Types . . . . . . . . . . . . . . . 47 - 6.2. Defining New Endpoint Parameters . . . . . . . . . . . . 47 + 6.1. Defining Access Token Types . . . . . . . . . . . . . . . 46 + 6.2. Defining New Endpoint Parameters . . . . . . . . . . . . 46 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 + 6.4. Defining New Authorization Endpoint Response Types . . . 47 + 6.5. Defining Additional Error Codes . . . . . . . . . . . . . 47 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 48 + 7.1. Access Token Security Considerations . . . . . . . . . . 48 + 7.1.1. Security Threats . . . . . . . . . . . . . . . . . . 48 + 7.1.2. Threat Mitigation . . . . . . . . . . . . . . . . . . 49 + 7.1.3. Summary of Recommendations . . . . . . . . . . . . . 51 + 7.1.4. Token Replay Prevention . . . . . . . . . . . . . . . 52 + 7.1.5. Access Token Privilege Restriction . . . . . . . . . 52 + 7.2. Client Authentication . . . . . . . . . . . . . . . . . . 53 + 7.2.1. Client Authentication of Native Apps . . . . . . . . 54 + 7.3. Registration of Native App Clients . . . . . . . . . . . 54 + 7.4. Client Impersonation . . . . . . . . . . . . . . . . . . 54 + 7.4.1. Impersonation of Native Apps . . . . . . . . . . . . 55 + 7.4.2. Access Token Privilege Restriction . . . . . . . . . 55 + 7.4.3. Access Token Replay Prevention . . . . . . . . . . . 56 + 7.5. Refresh Tokens . . . . . . . . . . . . . . . . . . . . . 56 + 7.6. Client Impersonating Resource Owner . . . . . . . . . . . 57 + 7.7. Protecting the Authorization Code Flow . . . . . . . . . 57 + 7.7.1. Loopback Redirect Considerations in Native Apps . . . 58 + 7.7.2. HTTP 307 Redirect . . . . . . . . . . . . . . . . . . 58 + 7.8. Authorization Codes . . . . . . . . . . . . . . . . . . . 59 + 7.9. Request Confidentiality . . . . . . . . . . . . . . . . . 60 + 7.10. Ensuring Endpoint Authenticity . . . . . . . . . . . . . 61 + 7.11. Credentials-Guessing Attacks . . . . . . . . . . . . . . 61 + 7.12. Phishing Attacks . . . . . . . . . . . . . . . . . . . . 61 + 7.13. Fake External User-Agents in Native Apps . . . . . . . . 62 + 7.14. Malicious External User-Agents in Native Apps . . . . . . 62 + 7.15. Cross-Site Request Forgery . . . . . . . . . . . . . . . 62 + 7.16. Clickjacking . . . . . . . . . . . . . . . . . . . . . . 63 + 7.17. Code Injection and Input Validation . . . . . . . . . . . 64 + 7.18. Open Redirectors . . . . . . . . . . . . . . . . . . . . 64 + 7.18.1. Client as Open Redirector . . . . . . . . . . . . . 64 + 7.18.2. Authorization Server as Open Redirector . . . . . . 65 - 7.19. Authorization Server Mix-Up Mitigation in Native Apps . . 67 - 7.20. Embedded User Agents in Native Apps . . . . . . . . . . . 67 - 7.21. Other Recommendations . . . . . . . . . . . . . . . . . . 68 - 8. Native Applications . . . . . . . . . . . . . . . . . . . . . 68 + 7.19. Authorization Server Mix-Up Mitigation in Native Apps . . 65 + 7.20. Embedded User Agents in Native Apps . . . . . . . . . . . 66 + 7.21. Other Recommendations . . . . . . . . . . . . . . . . . . 66 + 8. Native Applications . . . . . . . . . . . . . . . . . . . . . 67 8.1. Using Inter-App URI Communication for OAuth in Native - Apps . . . . . . . . . . . . . . . . . . . . . . . . . . 69 - 8.2. Initiating the Authorization Request from a Native App . 70 - 8.3. Receiving the Authorization Response in a Native App . . 70 - 8.3.1. Private-Use URI Scheme Redirection . . . . . . . . . 71 - 8.3.2. Claimed "https" Scheme URI Redirection . . . . . . . 72 - 8.3.3. Loopback Interface Redirection . . . . . . . . . . . 72 - 9. Browser-Based Apps . . . . . . . . . . . . . . . . . . . . . 73 - 10. Differences from OAuth 2.0 . . . . . . . . . . . . . . . . . 73 - 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 74 - 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 74 - 12.1. Normative References . . . . . . . . . . . . . . . . . . 74 - 12.2. Informative References . . . . . . . . . . . . . . . . . 77 - Appendix A. Augmented Backus-Naur Form (ABNF) Syntax . . . . . . 80 - A.1. "client_id" Syntax . . . . . . . . . . . . . . . . . . . 80 - A.2. "client_secret" Syntax . . . . . . . . . . . . . . . . . 80 - A.3. "response_type" Syntax . . . . . . . . . . . . . . . . . 80 - A.4. "scope" Syntax . . . . . . . . . . . . . . . . . . . . . 81 - A.5. "state" Syntax . . . . . . . . . . . . . . . . . . . . . 81 - A.6. "redirect_uri" Syntax . . . . . . . . . . . . . . . . . . 81 - A.7. "error" Syntax . . . . . . . . . . . . . . . . . . . . . 81 - A.8. "error_description" Syntax . . . . . . . . . . . . . . . 81 - A.9. "error_uri" Syntax . . . . . . . . . . . . . . . . . . . 81 - A.10. "grant_type" Syntax . . . . . . . . . . . . . . . . . . . 81 - A.11. "code" Syntax . . . . . . . . . . . . . . . . . . . . . . 82 - A.12. "access_token" Syntax . . . . . . . . . . . . . . . . . . 82 - A.13. "token_type" Syntax . . . . . . . . . . . . . . . . . . . 82 - A.14. "expires_in" Syntax . . . . . . . . . . . . . . . . . . . 82 - A.15. "refresh_token" Syntax . . . . . . . . . . . . . . . . . 82 - A.16. Endpoint Parameter Syntax . . . . . . . . . . . . . . . . 82 - A.17. "code_verifier" Syntax . . . . . . . . . . . . . . . . . 83 - A.18. "code_challenge" Syntax . . . . . . . . . . . . . . . . . 83 + Apps . . . . . . . . . . . . . . . . . . . . . . . . . . 68 + 8.2. Initiating the Authorization Request from a Native App . 68 + 8.3. Receiving the Authorization Response in a Native App . . 69 + 8.3.1. Private-Use URI Scheme Redirection . . . . . . . . . 69 + 8.3.2. Claimed "https" Scheme URI Redirection . . . . . . . 70 + 8.3.3. Loopback Interface Redirection . . . . . . . . . . . 71 + 9. Browser-Based Apps . . . . . . . . . . . . . . . . . . . . . 72 + 10. Differences from OAuth 2.0 . . . . . . . . . . . . . . . . . 72 + 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 73 + 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 73 + 12.1. Normative References . . . . . . . . . . . . . . . . . . 73 + 12.2. Informative References . . . . . . . . . . . . . . . . . 75 + Appendix A. Augmented Backus-Naur Form (ABNF) Syntax . . . . . . 79 + A.1. "client_id" Syntax . . . . . . . . . . . . . . . . . . . 79 + A.2. "client_secret" Syntax . . . . . . . . . . . . . . . . . 79 + A.3. "response_type" Syntax . . . . . . . . . . . . . . . . . 79 + A.4. "scope" Syntax . . . . . . . . . . . . . . . . . . . . . 79 + A.5. "state" Syntax . . . . . . . . . . . . . . . . . . . . . 80 + A.6. "redirect_uri" Syntax . . . . . . . . . . . . . . . . . . 80 + A.7. "error" Syntax . . . . . . . . . . . . . . . . . . . . . 80 + A.8. "error_description" Syntax . . . . . . . . . . . . . . . 80 + A.9. "error_uri" Syntax . . . . . . . . . . . . . . . . . . . 80 + A.10. "grant_type" Syntax . . . . . . . . . . . . . . . . . . . 80 + A.11. "code" Syntax . . . . . . . . . . . . . . . . . . . . . . 81 + A.12. "access_token" Syntax . . . . . . . . . . . . . . . . . . 81 + A.13. "token_type" Syntax . . . . . . . . . . . . . . . . . . . 81 + A.14. "expires_in" Syntax . . . . . . . . . . . . . . . . . . . 81 + A.15. "refresh_token" Syntax . . . . . . . . . . . . . . . . . 81 + A.16. Endpoint Parameter Syntax . . . . . . . . . . . . . . . . 81 + A.17. "code_verifier" Syntax . . . . . . . . . . . . . . . . . 81 + A.18. "code_challenge" Syntax . . . . . . . . . . . . . . . . . 82 Appendix B. Use of application/x-www-form-urlencoded Media - Type . . . . . . . . . . . . . . . . . . . . . . . . . . 83 - Appendix C. Extensions . . . . . . . . . . . . . . . . . . . . . 84 - Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 85 - Appendix E. Document History . . . . . . . . . . . . . . . . . . 85 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 86 + Type . . . . . . . . . . . . . . . . . . . . . . . . . . 82 + Appendix C. Extensions . . . . . . . . . . . . . . . . . . . . . 82 + Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 84 + Appendix E. Document History . . . . . . . . . . . . . . . . . . 84 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 85 1. Introduction In the traditional client-server authentication model, the client requests an access-restricted resource (protected resource) on the server by authenticating with the server using the resource owner's credentials. In order to provide third-party applications access to restricted resources, the resource owner shares its credentials with the third party. This creates several problems and limitations: @@ -447,21 +447,21 @@ credentials. The client authentication requirements are based on the client type and on the authorization server policies. 8. The authorization server authenticates the client and validates the refresh token, and if valid, issues a new access token (and, optionally, a new refresh token). 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 + 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 @@ -639,40 +639,48 @@ Dynamic Client Registration ([RFC7591]) defines a common general data model for clients that may be used even with manual client registration. 2.1. Client Types OAuth 2.1 defines three client types based on their ability to authenticate securely with the authorization server as well as the authorization server's assurance of the client's identity. - "confidential": Clients that have credentials and their identity has - been confirmed by the AS are designated as "confidential clients" + "confidential": Clients that have credentials and have a prior + relationship with the AS are designated as "confidential clients" - "credentialed": Clients that have credentials and their identity has - been not been confirmed by the AS are designated as "credentialed - clients" + "credentialed": Clients that have credentials but no prior + relationship with the AS are designated as "credentialed clients" "public": Clients without credentials are called "public clients" Any clients with credentials MUST take precautions to prevent leakage and abuse of their credentials. Authorization servers SHOULD consider the level of confidence in a client's identity when deciding whether they allow such a client access to more critical functions, such as the Client Credentials 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. + For example, a client that has been registered at the authorization + server by a registered application developer, where the client is + expected to be run as server-side code, would be considered a + confidential client. A client that runs on an end-user's device, and + uses Dynamic Client Registration ([RFC7591]) to establish credentials + the first time the app runs, would be considered a credentialed + client. An application deployed as a single-page app on a static web + host would be considered a public client. + This specification has been designed around the following client profiles: "web application": A web application is a confidential client 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 the resource owner. The client credentials as well as any access tokens issued to the client are stored on the web server and are not exposed to or accessible by the resource owner. @@ -705,21 +713,21 @@ secret; it is exposed to the resource owner and MUST NOT be used alone for client authentication. The client identifier is unique to the authorization server. The client identifier string size is left undefined by this specification. The client should avoid making assumptions about the identifier size. The authorization server SHOULD document the size of any identifier it issues. Authorization servers SHOULD NOT allow clients to choose or influence - their "client_id" value. See Section 7.6 for details. + their client_id value. See Section 7.6 for details. 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 @@ -728,57 +736,57 @@ 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 + 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 (".") + 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 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. + 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 @@ -795,29 +803,23 @@ 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 - authentication method with the authorization server suitable for the - security requirements of the authorization server. The authorization + If the client is confidential or credentialed, the authorization server MAY accept any form of client authentication meeting its - security requirements. - - Confidential and credentialed clients are typically issued (or - establish) a set of client credentials used for authenticating with - the authorization server (e.g., password, public/private key pair). + security requirements (e.g., password, public/private key pair). 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 @@ -825,28 +827,29 @@ [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. The authorization server MAY establish a client authentication method with public clients, which converts them to credentialed clients. However, the authorization server MUST NOT rely on credentialed client authentication for the purpose of identifying the client. The client MUST NOT use more than one authentication method in each - request. + request to prevent a conflict of which authentication mechanism is + authoritative for the request. 2.4.1. Client Secret Clients in possession of a client secret, sometimes known as a client password, MAY use the HTTP Basic authentication scheme as defined in [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 the username; the client secret is encoded using the same algorithm and used as the password. The authorization server MUST support the HTTP Basic authentication scheme for authenticating clients that were issued a client secret. For example (with extra line breaks for display purposes only): Authorization: Basic czZCaGRSa3F0Mzo3RmpmcDBaQnIxS3REUmJuZlZkbUl3 @@ -944,52 +947,52 @@ 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. Since requests to the authorization endpoint result in user authentication and the transmission of clear-text credentials (in the HTTP response), the authorization server MUST require the use of TLS as described in Section 1.5 when sending requests to the authorization endpoint. - The authorization server MUST support the use of the HTTP "GET" - method [RFC7231] for the authorization endpoint and MAY support the - use of the "POST" method as well. + The authorization server MUST support the use of the HTTP GET method + [RFC7231] for the authorization endpoint and MAY support the use of + the POST method as well. The authorization server MUST ignore unrecognized request parameters. Request and response parameters defined by this specification MUST NOT be included more than once. Parameters sent without a value MUST be treated as if they were omitted from the request. 3.2. Token Endpoint 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 4.3. The means through which the client obtains the location of the token endpoint are beyond the scope of this specification, but the location is typically provided in the service documentation and configured during development of the client, or provided in the authorization server's metadata document ([RFC8414]) and fetched programmatically 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) and MUST NOT include a fragment component. Since requests to the token endpoint result in the transmission of clear-text credentials (in the HTTP request and response), the authorization server MUST require the use of TLS as described in 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. The authorization server MUST ignore unrecognized request parameters. Parameters sent without a value MUST be treated as if they were omitted from the request. Request and response parameters defined by this specification MUST NOT be included more than once. 3.2.1. Client Authentication @@ -1011,34 +1014,34 @@ refresh tokens. * Implementing authentication management best practices, which require periodic credential rotation. Rotation of an entire set of refresh tokens can be challenging, while rotation of a single set of client credentials is significantly easier. 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" + 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 + 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 @@ -1056,74 +1059,74 @@ 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 - scope of the access request using the "scope" request parameter. In - turn, the authorization server uses the "scope" response parameter to + scope of the access request using the scope request parameter. In + turn, the authorization server uses the scope response parameter to inform the client of the scope of the access token issued. The value of the scope parameter is expressed as a list of space- delimited, case-sensitive strings. The strings are defined by the authorization server. If the value contains multiple space-delimited strings, their order does not matter, and each string adds an additional access range to the requested scope. scope = scope-token *( SP scope-token ) scope-token = 1*( %x21 / %x23-5B / %x5D-7E ) The authorization server MAY fully or partially ignore the scope requested by the client, based on the authorization server policy or the resource owner's instructions. If the issued access token scope is different from the one requested by the client, the authorization - server MUST include the "scope" response parameter to inform the - client of the actual scope granted. + server MUST include the scope response parameter to inform the client + of the actual scope granted. If the client omits the scope parameter when requesting authorization, the authorization server MUST either process the request using a pre-defined default value or fail the request indicating an invalid scope. The authorization server SHOULD document its scope requirements and default value (if defined). 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" + 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. + 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 + "scope": RECOMMENDED, 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 @@ -1136,24 +1139,23 @@ 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. + 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", @@ -1173,67 +1175,67 @@ 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. + 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" + 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. + 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 + 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 + 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 + 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 @@ -1343,223 +1345,221 @@ redirect the user agent to this URI to initiate the request. Clients use a unique secret per authorization request to protect against authorization code injection and CSRF attacks. The client first generates this secret, which it can use at the time of redeeming the authorization code to prove that the client using the authorization code is the same client that requested it. The client constructs the request URI by adding the following 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. 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 + 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. + 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, + 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 Section 2.2. "code_challenge": REQUIRED or RECOMMENDED (see Section 7.8). Code challenge. - "code_challenge_method": OPTIONAL, defaults to "plain" if not - present in the request. Code verifier transformation method is - "S256" or "plain". + "code_challenge_method": OPTIONAL, defaults to plain if not present + in the request. Code verifier transformation method is S256 or + plain. "redirect_uri": OPTIONAL. As described in Section 2.3. "scope": OPTIONAL. The scope of the access request as described by Section 3.2.2.1. "state": OPTIONAL. An opaque value used by the client to maintain state between the request and callback. The authorization server includes this value when redirecting the user agent back to the 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 - 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 characters. - The client stores the "code_verifier" temporarily, and calculates the - "code_challenge" which it uses in the authorization request. + The client stores the code_verifier temporarily, and calculates the + code_challenge which it uses in the authorization request. - ABNF for "code_verifier" is as follows. + ABNF for code_verifier is as follows. code-verifier = 43*128unreserved unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" ALPHA = %x41-5A / %x61-7A DIGIT = %x30-39 NOTE: The code verifier SHOULD have enough entropy to make it impractical to guess the value. It is RECOMMENDED that the output of a suitable random number generator be used to create a 32-octet sequence. The octet sequence is then base64url-encoded to produce a 43-octet URL-safe string to use as the code verifier. - The client then creates a "code_challenge" derived from the code + The client then creates a code_challenge derived from the code verifier by using one of the following transformations on the code verifier: S256 code_challenge = BASE64URL-ENCODE(SHA256(ASCII(code_verifier))) plain code_challenge = code_verifier - If the client is capable of using "S256", it MUST use "S256", as - "S256" is Mandatory To Implement (MTI) on the server. Clients are - permitted to use "plain" only if they cannot support "S256" for some - technical reason, for example constrained environments that do not - have a hashing function available, and know via out-of-band - configuration or via Authorization Server Metadata ([RFC8414]) that - the server supports "plain". + If the client is capable of using S256, it MUST use S256, as S256 is + Mandatory To Implement (MTI) on the server. Clients are permitted to + use plain only if they cannot support S256 for some technical reason, + for example constrained environments that do not have a hashing + function available, and know via out-of-band configuration or via + Authorization Server Metadata ([RFC8414]) that the server supports + plain. - ABNF for "code_challenge" is as follows. + ABNF for code_challenge is as follows. code-challenge = 43*128unreserved unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" ALPHA = %x41-5A / %x61-7A DIGIT = %x30-39 - The properties "code_challenge" and "code_verifier" are adopted from - the OAuth 2.0 extension known as "Proof-Key for Code Exchange", or - PKCE ([RFC7636]) where this technique was originally developed. + The properties code_challenge and code_verifier are adopted from the + OAuth 2.0 extension known as "Proof-Key for Code Exchange", or PKCE + ([RFC7636]) where this technique was originally developed. - Clients MUST use "code_challenge" and "code_verifier" and - authorization servers MUST enforce their use except under the - conditions described in Section 7.8. In this case, using and - enforcing "code_challenge" and "code_verifier" as described in the - following is still RECOMMENDED. + Clients MUST use code_challenge and code_verifier and authorization + servers MUST enforce their use except under the conditions described + in Section 7.8. In this case, using and enforcing code_challenge and + code_verifier as described in the following is still RECOMMENDED. The client directs the resource owner to the constructed URI using an HTTP redirection, or by other means available to it via the user agent. For example, the client directs the user agent to make the following HTTP request using TLS (with extra line breaks for display purposes only): GET /authorize?response_type=code&client_id=s6BhdRkqt3&state=xyz &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb &code_challenge=6fdkQaPm51l13DSukcAH3Mdx7_ntecHYd1vi3n0hMZY &code_challenge_method=S256 HTTP/1.1 Host: server.example.com The authorization server validates the request to ensure that all required parameters are present and valid. In particular, the authorization server MUST validate the - "redirect_uri" in the request if present, ensuring that it matches - one of the registered redirect URIs previously established during - client registration (Section 2). When comparing the two URIs the + redirect_uri in the request if present, ensuring that it matches one + of the registered redirect URIs previously established during client + registration (Section 2). When comparing the two URIs the authorization server MUST using simple character-by-character string comparison as defined in [RFC3986], Section 6.2.1. If the request is valid, the authorization server authenticates the resource owner and obtains an authorization decision (by asking the resource owner or by establishing approval via other means). When a decision is established, the authorization server directs the user agent to the provided client redirect URI using an HTTP redirection response, or by other means available to it via the user agent. 4.1.2. Authorization Response If the resource owner grants the access request, the authorization server issues an authorization code and delivers it to the client by adding the following parameters to the query component of the - redirect URI using the "application/x-www-form-urlencoded" format, - per Appendix B: + redirect URI using the application/x-www-form-urlencoded format, per + Appendix B: "code": REQUIRED. The authorization code generated by the - authorization server. The authorization code MUST expire shortly - after it is issued to mitigate the risk of leaks. A maximum - authorization code lifetime of 10 minutes is RECOMMENDED. The - client MUST NOT use the authorization code more than once. If an - authorization code is used more than once, the authorization - server MUST deny the request and SHOULD revoke (when possible) all - access tokens and refresh tokens previously issued based on that - authorization code. The authorization code is bound to the client - identifier and redirect URI. + authorization server and is opqaue to the client. The + authorization code MUST expire shortly after it is issued to + mitigate the risk of leaks. A maximum authorization code lifetime + of 10 minutes is RECOMMENDED. The client MUST NOT use the + authorization code more than once. If an authorization code is + used more than once, the authorization server MUST deny the + request and SHOULD revoke (when possible) all access tokens and + refresh tokens previously issued based on that authorization code. + The authorization code is bound to the client identifier, code + challenge 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. For example, the authorization server redirects the user agent by sending the following HTTP response: HTTP/1.1 302 Found Location: https://client.example.com/cb?code=SplxlOBeZQQYbYS6WxSbIA &state=xyz The client MUST ignore unrecognized response parameters. The authorization code string size is left undefined by this specification. The client should avoid making assumptions about code value sizes. The authorization server SHOULD document the size of any value it issues. - The authorization server MUST associate the "code_challenge" and - "code_challenge_method" values with the issued authorization code so + The authorization server MUST associate the code_challenge and + code_challenge_method values with the issued authorization code so the code challenge can be verified later. - The exact method that the server uses to associate the - "code_challenge" with the issued code is out of scope for this - specification. The code challenge could be stored on the server and - associated with the code there. The "code_challenge" and - "code_challenge_method" values may be stored in encrypted form in the - code itself, but the server MUST NOT include the "code_challenge" - value in a response parameter in a form that entities other than the - AS can extract. + The exact method that the server uses to associate the code_challenge + with the issued code is out of scope for this specification. The + code challenge could be stored on the server and associated with the + code there. The code_challenge and code_challenge_method values may + be stored in encrypted form in the code itself, but the server MUST + NOT include the code_challenge value in a response parameter in a + form that entities other than the AS can extract. 4.1.2.1. Error Response If the request fails due to a missing, invalid, or mismatching redirect URI, or if the client identifier is missing or invalid, the authorization server SHOULD inform the resource owner of the error and MUST NOT automatically redirect the user agent to the invalid 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 there is reasonable assurance that the client mitigates authorization 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 - authorization error response with "error" value set to - "invalid_request". The "error_description" or the response of - "error_uri" SHOULD explain the nature of error, e.g., transform - algorithm not supported. + authorization error response with error value set to invalid_request. + The error_description or the response of error_uri SHOULD explain the + nature of error, e.g., transform algorithm not supported. If the resource owner denies the access request or if the request fails for reasons other than a missing or invalid redirect URI, the authorization server informs the client by adding the following parameters to the query component of the redirect URI using the - "application/x-www-form-urlencoded" format, per Appendix B: + application/x-www-form-urlencoded format, per Appendix B: "error": REQUIRED. A single ASCII [USASCII] error code from the following: "invalid_request": The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed. "unauthorized_client": The client is not authorized to request an authorization code using this method. @@ -1578,97 +1578,97 @@ request. (This error code is needed because a 500 Internal Server Error HTTP status code cannot be returned to the client via an HTTP redirect.) "temporarily_unavailable": The authorization server is currently unable to handle the request due to a temporary overloading or maintenance of the server. (This error code is needed because a 503 Service Unavailable HTTP status code cannot be returned to the client via an HTTP redirect.) - Values for the "error" parameter MUST NOT include characters - outside the set %x20-21 / %x23-5B / %x5D-7E. + 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 + 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 + 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. - "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. For example, the authorization server redirects the user agent by sending the following HTTP response: HTTP/1.1 302 Found Location: https://client.example.com/cb?error=access_denied&state=xyz 4.1.3. Token Endpoint Extension The authorization grant type is identified at the token endpoint with - the "grant_type" value of "authorization_code". + the grant_type value of 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 authorization server. - "redirect_uri": REQUIRED, if the "redirect_uri" parameter was - included in the authorization request as described in - Section 4.1.1, and their values MUST be identical. + "redirect_uri": REQUIRED, if the redirect_uri parameter was included + in the authorization request as described in Section 4.1.1, and + their values MUST be identical. - "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 otherwise. The original code verifier string. 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 In addition to the processing rules in Section 3.2.2, the authorization server MUST: * ensure that the authorization code was issued to the authenticated 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 "code_verifier" parameter is present if and only - if a "code_challenge" parameter was present in the authorization + * verify that the code_verifier parameter is present if and only if + a code_challenge parameter was present in the authorization request, - * if a "code_verifier" is present, verify the "code_verifier" by - calculating the code challenge from the received "code_verifier" - and comparing it with the previously associated "code_challenge", - after first transforming it according to the - "code_challenge_method" method specified by the client, and + * if a code_verifier is present, verify the code_verifier by + calculating the code challenge from the received code_verifier and + comparing it with the previously associated code_challenge, after + first transforming it according to the code_challenge_method + method specified by the client, and - * ensure that the "redirect_uri" parameter is present if the - "redirect_uri" parameter was included in the initial authorization + * ensure that the redirect_uri parameter is present if the + redirect_uri parameter was included in the initial authorization request as described in Section 4.1.1, and if included ensure that their values are identical. 4.2. Client Credentials Grant The client can request an access token using only its client credentials (or other supported means of authentication) when the client is requesting access to the protected resources under its control, or those of another resource owner that have been previously arranged with the authorization server (the method of which is beyond @@ -1692,21 +1692,21 @@ (1) The client authenticates with the authorization server and requests an access token from the token endpoint. (2) The authorization server authenticates the client, and if valid, issues an access token. 4.2.1. Token Endpoint Extension The authorization grant type is identified at the token endpoint with - the "grant_type" value of "client_credentials". + the grant_type value of client_credentials. If this value is set, no additional parameters beyond Section 3.2.2 are required/supported: For example, the client makes the following HTTP request using transport-layer security (with extra line breaks for display purposes only): POST /token HTTP/1.1 Host: server.example.com @@ -1723,21 +1723,21 @@ to a client, which can be used to obtain new (fresh) access tokens based on an existing grant. The client uses this option either 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. 4.3.1. Token Endpoint Extension The authorization grant type is identified at the token endpoint with - the "grant_type" value of "refresh_token". + the grant_type value of 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. Because refresh tokens are typically long-lasting credentials used to request additional access tokens, the refresh token is bound to the client to which it was issued. Confidential or credentialed clients MUST authenticate with the authorization server as described in @@ -1811,21 +1812,21 @@ 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 the authorization server. It might be a global value or determined based on the client policy or the grant associated with the refresh token (and its sensitivity). 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 + 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 @@ -1853,192 +1854,198 @@ authorization server. For example, when the resource server and 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]. The method in which the client utilizes the access token to access protected resources at the resource server depends on the type of access token issued by the authorization server. Typically, it - involves using the HTTP "Authorization" request header field - [RFC7235] with an authentication scheme defined by the specification - of the access token type used, such as "Bearer", defined below. + involves using the HTTP Authorization request header field [RFC7235] + with an authentication scheme defined by the specification of the + access token type used, such as Bearer, defined below. 5.1. Access Token Types The access token type provides the client with the information required to successfully utilize the access token to make a protected resource request (along with type-specific attributes). The client MUST NOT use an access token if it does not understand the token 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: GET /resource/1 HTTP/1.1 Host: example.com Authorization: Bearer mF_9.B5f-4.1JqM The above example is provided for illustration purposes only. 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 include the access token when making a protected resource request. 5.2. Bearer Tokens 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 that any other party in possession of it can. Using a bearer token does not require a bearer to prove possession of cryptographic key material (proof-of-possession). - Bearer tokens may be extended to include proof-of-possession - techniques by other specifications. + Bearer tokens may be enhanced with proof-of-possession specifications + such as mTLS [RFC8705] to provide proof-of-possession + characteristics. 5.2.1. Authenticated Requests This section defines two methods of sending Bearer tokens in resource - requests to resource servers. Clients MUST NOT use more than one - method to transmit the token in each request. + requests to resource servers. Clients MUST use one of the two + methods defined below, and MUST NOT use more than one method to + transmit the token in each request. + + In particular, clients MUST NOT send the access token in a URI query + parameter, and resource servers MUST ignore access tokens in a URI + query parameter. 5.2.1.1. Authorization Request Header Field - When sending the access token in the "Authorization" request header - field defined by HTTP/1.1 [RFC7235], the client uses the "Bearer" + When sending the access token in the Authorization request header + field defined by HTTP/1.1 [RFC7235], the client uses the Bearer authentication scheme to transmit the access token. For example: GET /resource HTTP/1.1 Host: server.example.com Authorization: Bearer mF_9.B5f-4.1JqM - The syntax of the "Authorization" header field for this scheme - follows the usage of the Basic scheme defined in Section 2 of - [RFC2617]. Note that, as with Basic, it does not conform to the - generic syntax defined in Section 1.2 of [RFC2617] but is compatible - with the general authentication framework in HTTP 1.1 Authentication + The syntax of the Authorization header field for this scheme follows + the usage of the Basic scheme defined in Section 2 of [RFC2617]. + Note that, as with Basic, it does not conform to the generic syntax + defined in Section 1.2 of [RFC2617] but is compatible with the + general authentication framework in HTTP 1.1 Authentication [RFC7235], although it does not follow the preferred practice outlined therein in order to reflect existing deployments. The syntax for Bearer credentials is as follows: b64token = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" ) *"=" credentials = "Bearer" 1*SP b64token 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. 5.2.1.2. Form-Encoded Body Parameter 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 following conditions are met: - * The HTTP request entity-header includes the "Content-Type" header - field set to "application/x-www-form-urlencoded". + * The HTTP request entity-header includes the Content-Type header + field set to application/x-www-form-urlencoded. - * The payload follows the encoding requirements of the "application/ - x-www-form-urlencoded" content-type as defined by HTML 4.01 + * The payload follows the encoding requirements of the application/ + x-www-form-urlencoded content-type as defined by HTML 4.01 [W3C.REC-html401-19991224]. * The HTTP request payload is single-part. * The content to be encoded in the payload MUST consist entirely of ASCII [USASCII] characters. * The HTTP request method is one for which the request-body has - defined semantics. In particular, this means that the "GET" - method MUST NOT be used. + defined semantics. In particular, this means that the GET method + MUST NOT be used. The payload MAY include other request-specific parameters, in which - case the "access_token" parameter MUST be properly separated from the - request-specific parameters using "&" character(s) (ASCII code 38). + case the access_token parameter MUST be properly separated from the + request-specific parameters using & character(s) (ASCII code 38). For example, the client makes the following HTTP request using transport-layer security: POST /resource HTTP/1.1 Host: server.example.com Content-Type: application/x-www-form-urlencoded 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 - have access to the "Authorization" request header field. Resource + have access to the Authorization request header field. Resource servers MAY support this method. 5.2.2. The WWW-Authenticate Response Header Field If the protected resource request does not include authentication credentials or does not contain an access token that enables access to the protected resource, the resource server MUST include the HTTP - "WWW-Authenticate" response header field; it MAY include it in - response to other conditions as well. The "WWW-Authenticate" header - field uses the framework defined by HTTP/1.1 [RFC7235]. + WWW-Authenticate response header field; it MAY include it in response + to other conditions as well. The WWW-Authenticate header field uses + the framework defined by HTTP/1.1 [RFC7235]. All challenges for this token type MUST use the auth-scheme value - "Bearer". This scheme MUST be followed by one or more auth-param + Bearer. This scheme MUST be followed by one or more auth-param values. The auth-param attributes used or defined by this specification for this token type are as follows. Other auth-param attributes MAY be used as well. - A "realm" attribute MAY be included to indicate the scope of - protection in the manner described in HTTP/1.1 [RFC7235]. The - "realm" attribute MUST NOT appear more than once. + A realm attribute MAY be included to indicate the scope of protection + in the manner described in HTTP/1.1 [RFC7235]. The realm attribute + MUST NOT appear more than once. - The "scope" attribute is defined in Section 3.2.2.1. 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 indicating the required scope of the access token for accessing the - requested resource. "scope" values are implementation defined; there - is no centralized registry for them; allowed values are defined by - the authorization server. The order of "scope" values is not - significant. In some cases, the "scope" value will be used when - requesting a new access token with sufficient scope of access to - utilize the protected resource. Use of the "scope" attribute is - OPTIONAL. The "scope" attribute MUST NOT appear more than once. The - "scope" value is intended for programmatic use and is not meant to be - displayed to end-users. + requested resource. scope values are implementation defined; there is + no centralized registry for them; allowed values are defined by the + authorization server. The order of scope values is not significant. + In some cases, the scope value will be used when requesting a new + access token with sufficient scope of access to utilize the protected + resource. Use of the scope attribute is OPTIONAL. The scope + attribute MUST NOT appear more than once. The scope value is + intended for programmatic use and is not meant to be displayed to + end-users. Two example scope values follow; these are taken from the OpenID Connect [OpenID.Messages] and the Open Authentication Technology Committee (OATC) Online Multimedia Authorization Protocol [OMAP] OAuth 2.0 use cases, respectively: scope="openid profile email" scope="urn:example:channel=HBO&urn:example:rating=G,PG-13" 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 request was declined. The parameter value is described in 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 - MAY include the "error_uri" attribute with an absolute URI - identifying a human-readable web page explaining the error. The - "error", "error_description", and "error_uri" attributes MUST NOT - appear more than once. + MAY include the error_uri attribute with an absolute URI identifying + a human-readable web page explaining the error. The error, + error_description, and error_uri attributes MUST NOT 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 representing scope values and %x20 for delimiters between scope - values. Values for the "error" and "error_description" attributes + values. Values for the error and error_description attributes (specified in Appendixes A.7 and A.8) MUST NOT include characters outside the set %x20-21 / %x23-5B / %x5D-7E. Values for the - "error_uri" attribute (specified in Appendix A.9 of) MUST conform to + error_uri attribute (specified in Appendix A.9 of) MUST conform to the URI-reference syntax and thus MUST NOT include characters outside the set %x21 / %x23-5B / %x5D-7E. For example, in response to a protected resource request without authentication: HTTP/1.1 401 Unauthorized WWW-Authenticate: Bearer realm="example" And in response to a protected resource request with an @@ -2060,25 +2067,27 @@ same parameter, uses more than one method for including an access token, or is otherwise malformed. The resource server SHOULD respond with the HTTP 400 (Bad Request) status code. "invalid_token": The access token provided is expired, revoked, malformed, or invalid for other reasons. The resource SHOULD respond with the HTTP 401 (Unauthorized) status code. The client MAY request a new access token and retry the protected resource request. - "insufficient_scope": The request requires higher privileges than - provided by the access token. The resource server SHOULD respond - with the HTTP 403 (Forbidden) status code and MAY include the - "scope" attribute with the scope necessary to access the protected - resource. + "insufficient_scope": The request requires higher privileges + (scopes) than provided by the scopes granted to the client and + represented by the access token. + + The resource server SHOULD respond with the HTTP 403 (Forbidden) + status code and MAY include the scope attribute with the scope + necessary to access the protected resource. If the request lacks any authentication information (e.g., the client was unaware that authentication is necessary or attempted using an unsupported authentication method), the resource server SHOULD NOT include an error code or other error information. For example: HTTP/1.1 401 Unauthorized WWW-Authenticate: Bearer realm="example" @@ -2096,32 +2105,33 @@ (https://tools.ietf.org/html/rfc6749#section-11.4) for error values to be shared among OAuth token authentication schemes. New authentication schemes designed primarily for OAuth token authentication SHOULD define a mechanism for providing an error status code to the client, in which the error values allowed are registered in the error registry established by this specification. Such schemes MAY limit the set of valid error codes to a subset of the registered values. If the error code is returned using a named - parameter, the parameter name SHOULD be "error". + parameter, the parameter name SHOULD be error. Other schemes capable of being used for OAuth token authentication, but not primarily designed for that purpose, MAY bind their error values to the registry in the same manner. 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 specification. 6. Extensibility + 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 @@ -2124,21 +2134,21 @@ 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. + 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]. @@ -2152,65 +2162,65 @@ 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 + 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. + 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". + 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- @@ -2421,35 +2431,34 @@ restrictions also help to reduce the impact of access token leakage. In particular, access tokens SHOULD be restricted to certain resource servers (audience restriction), preferably to a single resource server. To put this into effect, the authorization server associates the access token with certain resource servers and every resource server is obliged to verify, for every request, whether the access token sent with that request was meant to be used for that particular resource server. If not, the resource server MUST refuse to serve the respective request. Clients and authorization servers MAY - utilize the parameters "scope" or "resource" as specified in this + utilize the parameters scope or resource as specified in this document and [RFC8707], respectively, to determine the resource server they want to access. Additionally, access tokens SHOULD be restricted to certain resources and actions on resource servers or resources. To put this into effect, the authorization server associates the access token with the respective resource and actions and every resource server is obliged to verify, for every request, whether the access token sent with that request was meant to be used for that particular action on the particular resource. If not, the resource server must refuse to serve the respective request. Clients and authorization servers MAY - utilize the parameter "scope" and "authorization_details" as - specified in [I-D.ietf-oauth-rar] to determine those resources and/or - actions. + utilize the parameter scope and authorization_details as specified in + [I-D.ietf-oauth-rar] to determine those resources and/or actions. 7.2. Client Authentication The authorization server MUST only rely on client authentication if the process of issuance/registration and distribution of the underlying credentials ensures their confidentiality. When client authentication is not possible, the authorization server SHOULD employ other means to validate the client's identity - for example, by requiring the registration of the client redirect URI or @@ -2476,21 +2485,21 @@ services or to use the client credentials grant type. 7.2.1. Client Authentication of Native Apps Secrets that are statically included as part of an app distributed to multiple users should not be treated as confidential secrets, as one user may inspect their copy and learn the shared secret. For this reason, it is NOT RECOMMENDED for authorization servers to require client authentication of public native apps clients using a shared 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 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 proof of the client's identity. Without additional measures, such clients are subject to client impersonation (see Section 7.4.1). 7.3. Registration of Native App Clients Except when using a mechanism like Dynamic Client Registration @@ -2504,21 +2513,21 @@ specific information, such as the app package or bundle name, or other information that may be useful for verifying the calling app's identity on operating systems that support such functions. 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 + 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 to protected resources if the impersonated client fails to, or is unable to, keep its client credentials confidential. The authorization server SHOULD enforce explicit resource owner @@ -2536,21 +2545,21 @@ 7.4.1. Impersonation of Native Apps As stated above, the authorization server SHOULD NOT process authorization requests automatically without user consent or interaction, except when the identity of the client can be assured. This includes the case where the user has previously approved an authorization request for a given client ID - unless the identity of the client can be proven, the request SHOULD be processed as if no 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 offer alternative platform-specific identity features that MAY be accepted, as appropriate. 7.4.2. Access Token Privilege Restriction The client SHOULD request access tokens with the minimal scope necessary. The authorization server SHOULD take the client identity into account when choosing how to honor the requested scope and MAY issue an access token with less rights than requested. @@ -2563,37 +2572,35 @@ restrictions also help to reduce the impact of access token leakage. In particular, access tokens SHOULD be restricted to certain resource servers (audience restriction), preferably to a single resource server. To put this into effect, the authorization server associates the access token with certain resource servers and every resource server is obliged to verify, for every request, whether the access token sent with that request was meant to be used for that particular resource server. If not, the resource server MUST refuse to serve the respective request. Clients and authorization servers MAY - utilize the parameters "scope" or "resource" as specified in - [RFC8707], respectively, to determine the resource server they want - to access. + utilize the parameters scope or resource as specified in [RFC8707], + respectively, to determine the resource server they want to access. 7.4.3. Access Token Replay Prevention Additionally, access tokens SHOULD be restricted to certain resources and actions on resource servers or resources. To put this into effect, the authorization server associates the access token with the respective resource and actions and every resource server is obliged to verify, for every request, whether the access token sent with that request was meant to be used for that particular action on the particular resource. If not, the resource server must refuse to serve the respective request. Clients and authorization servers MAY - utilize the parameter "scope" and "authorization_details" as - specified in [I-D.ietf-oauth-rar] to determine those resources and/or - actions. + utilize the parameter scope and authorization_details as specified in + [I-D.ietf-oauth-rar] to determine those resources and/or actions. Authorization and resource servers SHOULD use mechanisms for sender- constrained access tokens to prevent token replay as described in (#pop_tokens). A sender-constrained access token scopes the applicability of an access token to a certain sender. This sender is obliged to demonstrate knowledge of a certain secret as prerequisite 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 RECOMMENDED. @@ -2616,97 +2623,91 @@ or use refresh token rotation as described in (#refreshing-an-access- token). The authorization server MUST ensure that refresh tokens cannot be generated, modified, or guessed to produce valid refresh tokens by unauthorized parties. 7.6. Client Impersonating Resource Owner 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 response [RFC7662] or other mechanisms. If a client is able to - choose its own "client_id" during registration with the authorization - server, then there is a risk that it can register with the same "sub" + choose its own client_id during registration with the authorization + 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 the client credentials grant may be mistaken for an access token authorized by the privileged user if the resource server does not perform additional checks. Authorization servers SHOULD NOT allow clients to influence their - "client_id" or "sub" value or any other claim if that can cause - confusion with a genuine resource owner. Where this cannot be - avoided, authorization servers MUST provide other means for the - resource server to distinguish between access tokens authorized by a - resource owner from access tokens authorized by the client itself. + client_id or sub value or any other claim if that can cause confusion + with a genuine resource owner. Where this cannot be avoided, + authorization servers MUST provide other means for the resource + server to distinguish between access tokens authorized by a resource + owner from access tokens authorized by the client itself. 7.7. Protecting the Authorization Code Flow When comparing client redirect URIs against pre-registered URIs, authorization servers MUST utilize exact string matching. This measure contributes to the prevention of leakage of authorization codes and access tokens (see (#insufficient_uri_validation)). It can also help to detect mix-up attacks (see (#mix_up)). Clients MUST NOT expose URLs that forward the user's browser to arbitrary URIs obtained from a query parameter ("open redirector"). Open redirectors can enable exfiltration of authorization codes and access tokens, see (#open_redirector_on_client). Clients MUST prevent Cross-Site Request Forgery (CSRF). In this context, CSRF refers to requests to the redirection endpoint that do not originate at the authorization server, but a malicious third party (see Section 4.4.1.8. of [RFC6819] for details). Clients that have ensured that the authorization server supports the - "code_challenge" parameter MAY rely the CSRF protection provided by - that mechanism. In OpenID Connect flows, the "nonce" parameter + code_challenge parameter MAY rely the CSRF protection provided by + that mechanism. In OpenID Connect flows, the nonce parameter 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)). In order to prevent mix-up attacks (see (#mix_up)), clients MUST only process redirect responses of the authorization server they sent the respective request to and from the same user agent this authorization request was initiated with. Clients MUST store the authorization server they sent an authorization request to and bind this information to the user agent and check that the authorization response was received from the correct authorization server. Clients MUST ensure that the subsequent access token request, if applicable, is sent to the same authorization server. Clients SHOULD use distinct redirect URIs for each authorization server as a means to identify the authorization server a particular response came from. An AS that redirects a request potentially containing user credentials MUST avoid forwarding these user credentials accidentally (see Section 7.7.2 for details). 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 interface redirect URIs as the HTTP request never leaves the device. Clients should open the network port only when starting the authorization request and close it once the response is returned. Clients should listen on the loopback network interface only, in order to avoid interference by other network actors. - While redirect URIs using localhost (i.e., - "http://localhost:{port}/{path}") function similarly to loopback IP - redirects described in Section 8.3.3, the use of "localhost" is NOT - RECOMMENDED. Specifying a redirect URI with the loopback IP literal - rather than "localhost" avoids inadvertently listening on network - interfaces other than the loopback interface. It is also less - susceptible to client-side firewalls and misconfigured host name - resolution on the user's device. + Clients should use loopback IP literals rather than the string + localhost as described in Section 8.3.3. 7.7.2. HTTP 307 Redirect An AS which redirects a request that potentially contains user credentials MUST NOT use the HTTP 307 status code for redirection. If an HTTP redirection (and not, for example, JavaScript) is used for such a request, AS SHOULD use HTTP status code 303 "See Other". 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 @@ -2742,82 +2743,80 @@ authorization code for an access token, the authorization server SHOULD attempt to revoke all refresh and access tokens already granted based on the compromised authorization code. If the client can be authenticated, the authorization servers MUST authenticate the client and ensure that the authorization code was issued to the same client. Clients MUST prevent injection (replay) of authorization codes into the authorization response by attackers. To this end, using - "code_challenge" and "code_verifier" is REQUIRED for clients and + code_challenge and code_verifier is REQUIRED for clients and authorization servers MUST enforce their use, unless both of the following criteria are met: * The client is a confidential client. * In the specific deployment and the specific request, there is reasonable assurance for authorization server that the client - implements the OpenID Connect "nonce" mechanism properly. + implements the OpenID Connect nonce mechanism properly. - In this case, using and enforcing "code_challenge" and - "code_verifier" is still RECOMMENDED. + In this case, using and enforcing code_challenge and code_verifier is + still RECOMMENDED. - The "code_challenge" or OpenID Connect "nonce" value MUST be - transaction-specific and securely bound to the client and the user - agent in which the transaction was started. If a transaction leads - to an error, fresh values for "code_challenge" or "nonce" MUST be - chosen. + The code_challenge or OpenID Connect nonce value MUST be transaction- + specific and securely bound to the client and the user agent in which + the transaction was started. If a transaction leads to an error, + fresh values for code_challenge or nonce MUST be chosen. Historic note: Although PKCE [RFC7636] was originally designed as a mechanism to protect native apps, this advice applies to all kinds of OAuth clients, including web applications and other confidential clients. Clients SHOULD use code challenge methods that do not expose the - "code_verifier" in the authorization request. Otherwise, attackers + code_verifier in the authorization request. Otherwise, attackers that can read the authorization request (cf. Attacker A4 in (#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 authorization server MUST do the following check: - 1. If there was a "code_challenge" in the authorization request for - which this code was issued, there must be a "code_verifier" in - the token request, and it MUST be verified according to the steps - in Section 3.2.2. (This is no change from the current behavior - in [RFC7636].) + 1. If there was a code_challenge in the authorization request for + which this code was issued, there must be a code_verifier in the + token request, and it MUST be verified according to the steps in + Section 3.2.2. (This is no change from the current behavior in + [RFC7636].) - 2. If there was no "code_challenge" in the authorization request, - any request to the token endpoint containing a "code_verifier" - MUST be rejected. + 2. If there was no code_challenge in the authorization request, any + request to the token endpoint containing a code_verifier MUST be + rejected. - Authorization servers MUST support the "code_challenge" and - "code_verifier" parameters. + Authorization servers MUST support the code_challenge and + code_verifier parameters. Authorization servers MUST provide a way to detect their support for - the "code_challenge" mechanism. To this end, they MUST either (a) - publish the element "code_challenge_methods_supported" in their AS - metadata ([RFC8414]) containing the supported - "code_challenge_method"s (which can be used by the client to detect - support) or (b) provide a deployment-specific way to ensure or - determine support by the AS. + the code_challenge mechanism. To this end, they MUST either (a) + publish the element code_challenge_methods_supported in their AS + metadata ([RFC8414]) containing the supported code_challenge_methods + (which can be used by the client to detect support) or (b) provide a + deployment-specific way to ensure or determine support by the AS. 7.9. Request Confidentiality Access tokens, refresh tokens, authorization codes, and client credentials MUST NOT be transmitted in the clear. - The "state" and "scope" parameters SHOULD NOT include sensitive - client or resource owner information in plain text, as they can be - transmitted over insecure channels or stored insecurely. + The state and scope parameters SHOULD NOT include sensitive client or + resource owner information in plain text, as they can be transmitted + over insecure channels or stored insecurely. 7.10. Ensuring Endpoint Authenticity In order to prevent man-in-the-middle attacks, the authorization server MUST require the use of TLS with server authentication as defined by [RFC2818] for any request sent to the authorization and token endpoints. The client MUST validate the authorization server's TLS certificate as defined by [RFC6125] and in accordance with its requirements for server identity authentication. @@ -2879,53 +2878,53 @@ Users who are particularly concerned about their security when using 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 the authorization there, as most implementations of the in-app browser tab pattern offer such functionality. 7.14. Malicious External User-Agents in Native Apps 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 abuse this position of trust for malicious ends such as phishing the user. 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 OAuth usage by native apps. Many operating systems mitigate this 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. 7.15. Cross-Site Request Forgery 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 client to access resources under the attacker's control. This is a variant of an attack known as Cross-Site Request Forgery (CSRF). 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 - the "code_verifier" parameter or the OpenID Connect "nonce" value. + the code_verifier parameter or the OpenID Connect nonce value. - When using "code_verifier" instead of "state" or "nonce" for CSRF + When using code_verifier instead of state or nonce for CSRF protection, it is important to note that: - * Clients MUST ensure that the AS supports the - "code_challenge_method" intended to be used by the client. If an - authorization server does not support the requested method, - "state" or "nonce" MUST be used for CSRF protection instead. + * Clients MUST ensure that the AS supports the code_challenge_method + intended to be used by the client. If an authorization server + does not support the requested method, state or nonce MUST be used + for CSRF protection instead. - * If "state" is used for carrying application state, and integrity - of its contents is a concern, clients MUST protect "state" against + * If state is used for carrying application state, and integrity of + its contents is a concern, clients MUST protect state against tampering and swapping. This can be achieved by binding the contents of state to the browser session and/or signed/encrypted state values [I-D.bradley-oauth-jwt-encoded-state]. AS therefore MUST provide a way to detect their supported code challenge methods either via AS metadata according to [RFC8414] or provide a deployment-specific way to ensure or determine support. 7.16. Clickjacking @@ -2948,46 +2947,46 @@ origins in user agents that support CSP. The client MAY permit being framed by some other origin than the one used in its redirection endpoint. For this reason, authorization servers SHOULD allow administrators to configure allowed origins for particular clients and/or for clients to register these dynamically. Using CSP allows authorization servers to specify multiple origins in a single response header field and to constrain these using flexible patterns (see [CSP-2] for details). Level 2 of this standard provides a robust mechanism for protecting against clickjacking by - using policies that restrict the origin of frames (using "frame- - ancestors") together with those that restrict the sources of scripts - allowed to execute on an HTML page (by using "script-src"). A non- + using policies that restrict the origin of frames (using frame- + ancestors) together with those that restrict the sources of scripts + 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: - "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 - '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 SHOULD be combined with others, including those described in [RFC6819], unless such legacy user agents are explicitly unsupported by the authorization server. Even in such cases, additional countermeasures SHOULD still be employed. 7.17. Code Injection and Input Validation A code injection attack occurs when an input or otherwise external variable is used by an application unsanitized and causes modification to the application logic. This may allow an attacker to gain access to the application device or its data, cause denial of service, or introduce a wide range of malicious side-effects. The authorization server and client MUST sanitize (and validate when - possible) any value received - in particular, the value of the - "state" and "redirect_uri" parameters. + possible) any value received - in particular, the value of the state + and redirect_uri parameters. 7.18. Open Redirectors 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 browser to an arbitrary URI obtained from a query parameter. 7.18.1. Client as Open Redirector Clients MUST NOT expose open redirectors. Attackers may use open @@ -3006,21 +3005,21 @@ 7.18.2. Authorization Server as Open Redirector Just as with clients, attackers could try to utilize a user's trust in the authorization server (and its URL in particular) for performing phishing attacks. OAuth authorization servers regularly redirect users to other web sites (the clients), but must do so in a safe way. 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 - invalid combination of "client_id" and "redirect_uri". + invalid combination of client_id and redirect_uri. However, an attacker could also utilize a correctly registered redirect URI to perform phishing attacks. The attacker could, for example, register a client via dynamic client registration [RFC7591] and intentionally send an erroneous authorization request, e.g., by using an invalid scope value, thus instructing the AS to redirect the user agent to its phishing site. The AS MUST take precautions to prevent this threat. Based on its risk assessment, the AS needs to decide whether it can trust the @@ -3035,21 +3034,21 @@ To protect against a compromised or malicious authorization server attacking another authorization server used by the same app, it is REQUIRED that a unique redirect URI is used for each authorization server used by the app (for example, by varying the path component), and that authorization responses are rejected if the redirect URI they were received on doesn't match the redirect URI in an outgoing authorization request. 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 authorization response was received exactly matches it. The requirement of Section 7.3, specifically that authorization servers reject requests with URIs that don't match what was registered, is also required to prevent such attacks. 7.20. Embedded User Agents in Native Apps Embedded user agents are a technically possible method for @@ -3078,23 +3077,22 @@ site first. Aside from the security concerns, embedded user agents do not share the authentication state with other apps or the browser, requiring the user to log in for every authorization request, which is often considered an inferior user experience. 7.21. Other Recommendations Authorization servers SHOULD NOT allow clients to influence their - "client_id" or "sub" value or any other claim if that can cause - confusion with a genuine resource owner (see - (#client_impersonating)). + client_id or sub value or any other claim if that can cause confusion + with a genuine resource owner (see (#client_impersonating)). 8. Native Applications Native applications are clients installed and executed on the device used by the resource owner (i.e., desktop application, native mobile application). Native applications require special consideration related to security, platform capabilities, and overall end-user experience. The authorization endpoint requires interaction between the client @@ -3169,21 +3167,21 @@ 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 return the authorization response to the native app in different platforms are documented in Section 8.3. Any redirect URI that allows the app to receive the URI and inspect its parameters is viable. After constructing the authorization request URI, the app uses platform-specific APIs to open the URI in an external user agent. 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 other categories of external user agents MAY be used. This best practice focuses on the browser as the RECOMMENDED external user agent for native apps. An external user agent designed specifically for user authorization and capable of processing authorization requests and responses like a browser MAY also be used. Other external user agents, such as a native app provided by the authorization server may meet the criteria set out in this best practice, including using the same redirect URI properties, but their @@ -3207,106 +3205,117 @@ least the three redirect URI options described in the following subsections to native apps. Native apps MAY use whichever redirect option suits their needs best, taking into account platform-specific implementation details. 8.3.1. Private-Use URI Scheme Redirection Many mobile and desktop computing platforms support inter-app communication via URIs by allowing apps to register private-use URI 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 is launched to handle the request. To perform an authorization request with a private-use URI scheme redirect, the native app launches the browser with a standard authorization request, but one where the redirect URI utilizes a private-use URI scheme it registered with the operating system. When choosing a URI scheme to associate with the app, apps MUST use a URI scheme based on a domain name under their control, expressed in reverse order, as recommended by Section 3.8 of [RFC7595] for private-use URI schemes. - For example, an app that controls the domain name "app.example.com" - can use "com.example.app" as their scheme. Some authorization - servers assign client identifiers based on domain names, for example, - "client1234.usercontent.example.net", which can also be used as the + For example, an app that controls the domain name app.example.com can + use com.example.app as their scheme. Some authorization servers + assign client identifiers based on domain names, for example, + client1234.usercontent.example.net, which can also be used as the domain name for the scheme when reversed in the same manner. A - scheme such as "myapp", however, would not meet this requirement, as - it is not based on a domain name. + scheme such as myapp, however, would not meet this requirement, as it + is not based on a domain name. When there are multiple apps by the same publisher, care must be taken so that each scheme is unique within that group. On platforms that use app identifiers based on reverse-order domain names, those identifiers can be reused as the private-use URI scheme for the OAuth redirect to help avoid this problem. Following the requirements of Section 3.2 of [RFC3986], as there is 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: com.example.app:/oauth2redirect/example-provider + When the authorization server completes the request, it redirects to 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 launching the native app, passing in the URI as a launch parameter. Then, the native app uses normal processing for the authorization response. 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 claimed URI, instead of the page being loaded in the browser, the 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 indistinguishable to the authorization server from a regular web- based client redirect URI. An example is: https://app.example.com/oauth2redirect/example-provider As the redirect URI alone is not enough to distinguish public native app clients from confidential web clients, it is REQUIRED in Section 7.3 that the client type be recorded during client registration to enable the server to determine the client type and act accordingly. - App-claimed "https" scheme redirect URIs have some advantages - compared to other native app redirect options in that the identity of - the destination app is guaranteed to the authorization server by the + App-claimed https scheme redirect URIs have some advantages compared + to other native app redirect options in that the identity of the + destination app is guaranteed to the authorization server by the operating system. For this reason, native apps SHOULD use them over the other options where possible. 8.3.3. Loopback Interface Redirection Native apps that are able to open a port on the loopback network interface without needing special permissions (typically, those on desktop operating systems) can use the loopback interface to receive 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. - That is, "http://127.0.0.1:{port}/{path}" for IPv4, and - "http://[::1]:{port}/{path}" for IPv6. An example redirect using the + That is, http://127.0.0.1:{port}/{path} for IPv4, and + http://[::1]:{port}/{path} for IPv6. An example redirect using the IPv4 loopback interface with a randomly assigned port: http://127.0.0.1:51004/oauth2redirect/example-provider + An example redirect using the IPv6 loopback interface with a randomly assigned port: http://[::1]:61023/oauth2redirect/example-provider + While redirect URIs using the name localhost (i.e., + http://localhost:{port}/{path}) function similarly to loopback IP + redirects, the use of localhost is NOT RECOMMENDED. Specifying a + redirect URI with the loopback IP literal rather than localhost + avoids inadvertently listening on network interfaces other than the + loopback interface. It is also less susceptible to client-side + firewalls and misconfigured host name resolution on the user's + device. + The authorization server MUST allow any port to be specified at the time of the request for loopback IP redirect URIs, to accommodate clients that obtain an available ephemeral port from the operating system at the time of the request. Clients SHOULD NOT assume that the device supports a particular version of the Internet Protocol. It is RECOMMENDED that clients attempt to bind to the loopback interface using both IPv4 and IPv6 and use whichever is available. @@ -3337,21 +3346,21 @@ A non-normative list of changes from OAuth 2.0 is listed below: * The authorization code grant is extended with the functionality from PKCE ([RFC7636]) such that the default method of using the authorization code grant according to this specification requires the addition of the PKCE parameters * Redirect URIs must be compared using exact string matching as per Section 4.1.3 of [I-D.ietf-oauth-security-topics] - * The Implicit grant ("response_type=token") is omitted from this + * The Implicit grant (response_type=token) is omitted from this specification as per Section 2.1.2 of [I-D.ietf-oauth-security-topics] * The Resource Owner Password Credentials grant is omitted from this specification as per Section 2.4 of [I-D.ietf-oauth-security-topics] * Bearer token usage omits the use of bearer tokens in the query string of URIs as per Section 4.3.2 of [I-D.ietf-oauth-security-topics] @@ -3534,23 +3543,23 @@ [I-D.ietf-oauth-par] Lodderstedt, T., Campbell, B., Sakimura, N., Tonge, D., and F. Skokan, "OAuth 2.0 Pushed Authorization Requests", Work in Progress, Internet-Draft, draft-ietf-oauth-par-10, 29 July 2021, . [I-D.ietf-oauth-rar] Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0 Rich Authorization Requests", Work in Progress, Internet- - Draft, draft-ietf-oauth-rar-05, 15 May 2021, + Draft, draft-ietf-oauth-rar-07, 12 September 2021, . + 07.txt>. [I-D.ietf-oauth-token-binding] Jones, M. B., Campbell, B., Bradley, J., and W. Denniss, "OAuth 2.0 Token Binding", Work in Progress, Internet- Draft, draft-ietf-oauth-token-binding-08, 19 October 2018, . [NIST800-63] Burr, W., Dodson, D., Newton, E., Perlner, R., Polk, T., @@ -3655,152 +3664,151 @@ NQSCHAR = %x20-21 / %x23-5B / %x5D-7E UNICODECHARNOCRLF = %x09 /%x20-7E / %x80-D7FF / %xE000-FFFD / %x10000-10FFFF (The UNICODECHARNOCRLF definition is based upon the Char definition in Section 2.2 of [W3C.REC-xml-20081126], but omitting the Carriage Return and Linefeed characters.) A.1. "client_id" Syntax - The "client_id" element is defined in Section 2.4.1: + The client_id element is defined in Section 2.4.1: client-id = *VSCHAR A.2. "client_secret" Syntax - The "client_secret" element is defined in Section 2.4.1: + The client_secret element is defined in Section 2.4.1: client-secret = *VSCHAR A.3. "response_type" Syntax - The "response_type" element is defined in Section 4.1.1 and + The response_type element is defined in Section 4.1.1 and Section 6.4: response-type = response-name *( SP response-name ) response-name = 1*response-char response-char = "_" / DIGIT / ALPHA A.4. "scope" Syntax - The "scope" element is defined in Section 3.2.2.1: + The scope element is defined in Section 3.2.2.1: scope = scope-token *( SP scope-token ) scope-token = 1*NQCHAR 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: state = 1*VSCHAR 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: redirect-uri = URI-reference 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 3.2.3.1, 7.2, and 8.5: error = 1*NQSCHAR A.8. "error_description" Syntax - The "error_description" element is defined in Sections - Section 4.1.2.1, Section 3.2.3.1, and Section 5.3: + The error_description element is defined in Sections Section 4.1.2.1, + Section 3.2.3.1, and Section 5.3: error-description = 1*NQSCHAR 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 3.2.3.1, and 7.2: error-uri = URI-reference A.10. "grant_type" Syntax - The "grant_type" element is defined in Section Section 3.2.2: + The grant_type element is defined in Section Section 3.2.2: grant-type = grant-name / URI-reference grant-name = 1*name-char name-char = "-" / "." / "_" / DIGIT / ALPHA 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 A.12. "access_token" Syntax - The "access_token" element is defined in Section 3.2.3: + The access_token element is defined in Section 3.2.3: access-token = 1*VSCHAR A.13. "token_type" Syntax - The "token_type" element is defined in Section 3.2.3, and - Section 6.1: + The token_type element is defined in Section 3.2.3, and Section 6.1: token-type = type-name / URI-reference type-name = 1*name-char name-char = "-" / "." / "_" / DIGIT / ALPHA A.14. "expires_in" Syntax - The "expires_in" element is defined in Section 3.2.3: + The expires_in element is defined in Section 3.2.3: expires-in = 1*DIGIT A.15. "refresh_token" Syntax - The "refresh_token" element is defined in Section 3.2.3 and + The refresh_token element is defined in Section 3.2.3 and Section 4.3: refresh-token = 1*VSCHAR A.16. Endpoint Parameter Syntax The syntax for new endpoint parameters is defined in Section 6.2: param-name = 1*name-char name-char = "-" / "." / "_" / DIGIT / ALPHA A.17. "code_verifier" Syntax - ABNF for "code_verifier" is as follows. + ABNF for code_verifier is as follows. code-verifier = 43*128unreserved unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" ALPHA = %x41-5A / %x61-7A DIGIT = %x30-39 A.18. "code_challenge" Syntax - ABNF for "code_challenge" is as follows. + ABNF for code_challenge is as follows. code-challenge = 43*128unreserved unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" ALPHA = %x41-5A / %x61-7A DIGIT = %x30-39 Appendix B. Use of application/x-www-form-urlencoded Media Type - At the time of publication of this specification, the "application/x- - www-form-urlencoded" media type was defined in Section 17.13.4 of + At the time of publication of this specification, the application/x- + www-form-urlencoded media type was defined in Section 17.13.4 of [W3C.REC-html401-19991224] but not registered in the IANA MIME Media Types registry (http://www.iana.org/assignments/media-types (http://www.iana.org/assignments/media-types)). Furthermore, that definition is incomplete, as it does not consider non-US-ASCII characters. To address this shortcoming when generating payloads using this media type, names and values MUST be encoded using the UTF-8 character encoding scheme [RFC3629] first; the resulting octet sequence then needs to be further encoded using the escaping rules defined in @@ -3887,47 +3895,57 @@ * [I-D.ietf-oauth-par]: Pushed Authorization Requests - The Pushed Authorization Requests extension describes a technique of initiating an OAuth flow from the back channel, providing better security and more flexibility for building complex authorization requests. * [I-D.ietf-oauth-rar]: Rich Authorization Requests - 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. Appendix D. Acknowledgements TBD Appendix E. Document History [[ To be removed from the final specification ]] + -04 + +* Added explicit mention of not sending access tokens in URI query strings +* Clarifications on definition of client types +* Consolidated text around loopback vs localhost +* Editorial clarifications throughout the document + -03 - * refactored structure +* refactoring to collect all the grant types under the same top-level header in section 4 +* Better split normative and security consideration text into the appropriate places, both moving text that was really security considerations out of the main part of the document, as well as pulling normative requirements from the security considerations sections into the appropriate part of the main document +* Incorporated many of the published errata on RFC6749 +* Updated references to various RFCs +* Editorial clarifications throughout the document -02 -01 -00 - * initial revision Authors' Addresses Dick Hardt - SignIn.Org + Hellō Email: dick.hardt@gmail.com Aaron Parecki Okta Email: aaron@parecki.com URI: https://aaronparecki.com Torsten Lodderstedt