Internet Engineering Task Force (IETF) D. Hardt, Ed.
Request for Comments: 6749 Microsoft
Obsoletes: 5849 October 2012
Category: Standards Track
ISSN: 2070-1721
The OAuth 2.0 Authorization Framework
Abstract
The OAuth 2.0 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 the HTTP service, or by allowing the
third-party application to obtain access on its own behalf. This
specification replaces and obsoletes the OAuth 1.0 protocol described
in RFC 5849.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6749.
Copyright Notice
Copyright (c) 2012 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Hardt Standards Track [Page 1]
RFC 6749 OAuth 2.0 October 2012
Table of Contents
1. Introduction ....................................................4
1.1. Roles ......................................................6
1.2. Protocol Flow ..............................................7
1.3. Authorization Grant ........................................8
1.3.1. Authorization Code ..................................8
1.3.2. Implicit ............................................8
1.3.3. Resource Owner Password Credentials .................9
1.3.4. Client Credentials ..................................9
1.4. Access Token ..............................................10
1.5. Refresh Token .............................................10
1.6. TLS Version ...............................................12
1.7. HTTP Redirections .........................................12
1.8. Interoperability ..........................................12
1.9. Notational Conventions ....................................13
2. Client Registration ............................................13
2.1. Client Types ..............................................14
2.2. Client Identifier .........................................15
2.3. Client Authentication .....................................16
2.3.1. Client Password ....................................16
2.3.2. Other Authentication Methods .......................17
2.4. Unregistered Clients ......................................17
3. Protocol Endpoints .............................................18
3.1. Authorization Endpoint ....................................18
3.1.1. Response Type ......................................19
3.1.2. Redirection Endpoint ...............................19
3.2. Token Endpoint ............................................21
3.2.1. Client Authentication ..............................22
3.3. Access Token Scope ........................................23
4. Obtaining Authorization ........................................23
4.1. Authorization Code Grant ..................................24
4.1.1. Authorization Request ..............................25
4.1.2. Authorization Response .............................26
4.1.3. Access Token Request ...............................29
4.1.4. Access Token Response ..............................30
4.2. Implicit Grant ............................................31
4.2.1. Authorization Request ..............................33
4.2.2. Access Token Response ..............................35
4.3. Resource Owner Password Credentials Grant .................37
4.3.1. Authorization Request and Response .................39
4.3.2. Access Token Request ...............................39
4.3.3. Access Token Response ..............................40
4.4. Client Credentials Grant ..................................40
4.4.1. Authorization Request and Response .................41
4.4.2. Access Token Request ...............................41
4.4.3. Access Token Response ..............................42
4.5. Extension Grants ..........................................42
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RFC 6749 OAuth 2.0 October 2012
5. Issuing an Access Token ........................................43
5.1. Successful Response .......................................43
5.2. Error Response ............................................45
6. Refreshing an Access Token .....................................47
7. Accessing Protected Resources ..................................48
7.1. Access Token Types ........................................49
7.2. Error Response ............................................49
8. Extensibility ..................................................50
8.1. Defining Access Token Types ...............................50
8.2. Defining New Endpoint Parameters ..........................50
8.3. Defining New Authorization Grant Types ....................51
8.4. Defining New Authorization Endpoint Response Types ........51
8.5. Defining Additional Error Codes ...........................51
9. Native Applications ............................................52
10. Security Considerations .......................................53
10.1. Client Authentication ....................................53
10.2. Client Impersonation .....................................54
10.3. Access Tokens ............................................55
10.4. Refresh Tokens ...........................................55
10.5. Authorization Codes ......................................56
10.6. Authorization Code Redirection URI Manipulation ..........56
10.7. Resource Owner Password Credentials ......................57
10.8. Request Confidentiality ..................................58
10.9. Ensuring Endpoint Authenticity ...........................58
10.10. Credentials-Guessing Attacks ............................58
10.11. Phishing Attacks ........................................58
10.12. Cross-Site Request Forgery ..............................59
10.13. Clickjacking ............................................60
10.14. Code Injection and Input Validation .....................60
10.15. Open Redirectors ........................................60
10.16. Misuse of Access Token to Impersonate Resource
Owner in Implicit Flow ..................................61
11. IANA Considerations ...........................................62
11.1. OAuth Access Token Types Registry ........................62
11.1.1. Registration Template .............................62
11.2. OAuth Parameters Registry ................................63
11.2.1. Registration Template .............................63
11.2.2. Initial Registry Contents .........................64
11.3. OAuth Authorization Endpoint Response Types Registry .....66
11.3.1. Registration Template .............................66
11.3.2. Initial Registry Contents .........................67
11.4. OAuth Extensions Error Registry ..........................67
11.4.1. Registration Template .............................68
12. References ....................................................68
12.1. Normative References .....................................68
12.2. Informative References ...................................70
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RFC 6749 OAuth 2.0 October 2012
Appendix A. Augmented Backus-Naur Form (ABNF) Syntax ..............71
A.1. "client_id" Syntax ........................................71
A.2. "client_secret" Syntax ....................................71
A.3. "response_type" Syntax ....................................71
A.4. "scope" Syntax ............................................72
A.5. "state" Syntax ............................................72
A.6. "redirect_uri" Syntax .....................................72
A.7. "error" Syntax ............................................72
A.8. "error_description" Syntax ................................72
A.9. "error_uri" Syntax ........................................72
A.10. "grant_type" Syntax .......................................73
A.11. "code" Syntax .............................................73
A.12. "access_token" Syntax .....................................73
A.13. "token_type" Syntax .......................................73
A.14. "expires_in" Syntax .......................................73
A.15. "username" Syntax .........................................73
A.16. "password" Syntax .........................................73
A.17. "refresh_token" Syntax ....................................74
A.18. Endpoint Parameter Syntax .................................74
Appendix B. Use of application/x-www-form-urlencoded Media Type ...74
Appendix C. Acknowledgements ......................................75
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:
o Third-party applications are required to store the resource
owner's credentials for future use, typically a password in
clear-text.
o Servers are required to support password authentication, despite
the security weaknesses inherent in passwords.
o Third-party applications gain overly broad access to the resource
owner's protected resources, leaving resource owners without any
ability to restrict duration or access to a limited subset of
resources.
o Resource owners cannot revoke access to an individual third party
without revoking access to all third parties, and must do so by
changing the third party's password.
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RFC 6749 OAuth 2.0 October 2012
o Compromise of any third-party application results in compromise of
the end-user's password and all of the data protected by that
password.
OAuth addresses these issues by introducing an authorization layer
and separating the role of the client from that of the resource
owner. In OAuth, the client requests access to resources controlled
by the resource owner and hosted by the resource server, and is
issued a different set of credentials than those of the resource
owner.
Instead of using the resource owner's credentials to access protected
resources, the client obtains an access token -- a string denoting a
specific scope, lifetime, and other access attributes. Access tokens
are issued to third-party clients by an authorization server with the
approval of the resource owner. The client uses the access token to
access the protected resources hosted by the resource server.
For example, an end-user (resource owner) can grant a printing
service (client) access to her protected photos stored at a photo-
sharing service (resource server), without sharing her username and
password with the printing service. Instead, she authenticates
directly with a server trusted by the photo-sharing service
(authorization server), which issues the printing service delegation-
specific credentials (access token).
This specification is designed for use with HTTP ([RFC2616]). The
use of OAuth over any protocol other than HTTP is out of scope.
The OAuth 1.0 protocol ([RFC5849]), published as an informational
document, was the result of a small ad hoc community effort. This
Standards Track specification builds on the OAuth 1.0 deployment
experience, as well as additional use cases and extensibility
requirements gathered from the wider IETF community. The OAuth 2.0
protocol is not backward compatible with OAuth 1.0. The two versions
may co-exist on the network, and implementations may choose to
support both. However, it is the intention of this specification
that new implementations support OAuth 2.0 as specified in this
document and that OAuth 1.0 is used only to support existing
deployments. The OAuth 2.0 protocol shares very few implementation
details with the OAuth 1.0 protocol. Implementers familiar with
OAuth 1.0 should approach this document without any assumptions as to
its structure and details.
Hardt Standards Track [Page 5]
RFC 6749 OAuth 2.0 October 2012
1.1. Roles
OAuth defines four roles:
resource owner
An entity capable of granting access to a protected resource.
When the resource owner is a person, it is referred to as an
end-user.
resource server
The server hosting the protected resources, capable of accepting
and responding to protected resource requests using access tokens.
client
An application making protected resource requests on behalf of the
resource owner and with its authorization. The term "client" does
not imply any particular implementation characteristics (e.g.,
whether the application executes on a server, a desktop, or other
devices).
authorization server
The server issuing access tokens to the client after successfully
authenticating the resource owner and obtaining authorization.
The interaction between the authorization server and resource server
is beyond the scope of this specification. The authorization server
may be the same server as the resource server or a separate entity.
A single authorization server may issue access tokens accepted by
multiple resource servers.
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RFC 6749 OAuth 2.0 October 2012
1.2. Protocol Flow
+--------+ +---------------+
| |--(A)- Authorization Request ->| Resource |
| | | Owner |
| || Authorization |
| Client | | Server |
| || Resource |
| | | Server |
| || |
| | | |
| || | | |
| | | | | |
| || | | |
| | | | | |
| || |
| | | |
| || |
| User- | | Authorization |
| Agent -+----(B)-- User authenticates --->| Server |
| | | |
| -+----(C)-- Authorization Code ------(D)-- Authorization Code ---------' |
| Client | & Redirection URI |
| | |
| || |
| User- | | Authorization |
| Agent -|----(B)-- User authenticates -->| Server |
| | | |
| || Web-Hosted |
| | without Fragment | Client |
| | | Resource |
| (F) |--(B)---- Resource Owner ------->| |
| | Password Credentials | Authorization |
| Client | | Server |
| |--(A)- Client Authentication --->| Authorization |
| Client | | Server |
| |.
[W3C.REC-xml-20081126]
Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E.,
and F. Yergeau, "Extensible Markup Language (XML) 1.0
(Fifth Edition)", World Wide Web Consortium
Recommendation REC-xml-20081126, November 2008,