draft-ietf-oauth-v2-22.txt   draft-ietf-oauth-v2-23.txt 
Network Working Group E. Hammer-Lahav, Ed. Network Working Group E. Hammer, Ed.
Internet-Draft Yahoo! Internet-Draft
Obsoletes: 5849 (if approved) D. Recordon Obsoletes: 5849 (if approved) D. Recordon
Intended status: Standards Track Facebook Intended status: Standards Track Facebook
Expires: March 25, 2012 D. Hardt Expires: July 24, 2012 D. Hardt
Microsoft Microsoft
September 22, 2011 January 21, 2012
The OAuth 2.0 Authorization Protocol The OAuth 2.0 Authorization Protocol
draft-ietf-oauth-v2-22 draft-ietf-oauth-v2-23
Abstract Abstract
The OAuth 2.0 authorization protocol enables a third-party The OAuth 2.0 authorization protocol enables a third-party
application to obtain limited access to an HTTP service, either on application to obtain limited access to an HTTP service, either on
behalf of a resource owner by orchestrating an approval interaction behalf of a resource owner by orchestrating an approval interaction
between the resource owner and the HTTP service, or by allowing the between the resource owner and the HTTP service, or by allowing the
third-party application to obtain access on its own behalf. This third-party application to obtain access on its own behalf. This
specification replaces and obsoletes the OAuth 1.0 protocol described specification replaces and obsoletes the OAuth 1.0 protocol described
in RFC 5849. in RFC 5849.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on March 25, 2012. This Internet-Draft will expire on July 24, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.1. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 6 1.2. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 6
1.3. Authorization Grant . . . . . . . . . . . . . . . . . . . 7 1.3. Authorization Grant . . . . . . . . . . . . . . . . . . . 7
1.3.1. Authorization Code . . . . . . . . . . . . . . . . . . 7 1.3.1. Authorization Code . . . . . . . . . . . . . . . . . . 7
1.3.2. Implicit . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.2. Implicit . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.3. Resource Owner Password Credentials . . . . . . . . . 8 1.3.3. Resource Owner Password Credentials . . . . . . . . . 8
1.3.4. Client Credentials . . . . . . . . . . . . . . . . . . 8 1.3.4. Client Credentials . . . . . . . . . . . . . . . . . . 9
1.4. Access Token . . . . . . . . . . . . . . . . . . . . . . 9 1.4. Access Token . . . . . . . . . . . . . . . . . . . . . . 9
1.5. Refresh Token . . . . . . . . . . . . . . . . . . . . . . 9 1.5. Refresh Token . . . . . . . . . . . . . . . . . . . . . . 9
1.6. Notational Conventions . . . . . . . . . . . . . . . . . 11 1.6. TLS Version . . . . . . . . . . . . . . . . . . . . . . . 11
2. Client Registration . . . . . . . . . . . . . . . . . . . . . 11 1.7. Interoperability . . . . . . . . . . . . . . . . . . . . 11
2.1. Client Types . . . . . . . . . . . . . . . . . . . . . . 12 1.8. Notational Conventions . . . . . . . . . . . . . . . . . 12
2.2. Client Identifier . . . . . . . . . . . . . . . . . . . . 13 2. Client Registration . . . . . . . . . . . . . . . . . . . . . 12
2.3. Client Authentication . . . . . . . . . . . . . . . . . . 13 2.1. Client Types . . . . . . . . . . . . . . . . . . . . . . 13
2.3.1. Client Password . . . . . . . . . . . . . . . . . . . 13 2.2. Client Identifier . . . . . . . . . . . . . . . . . . . . 14
2.3.2. Other Authentication Methods . . . . . . . . . . . . . 14 2.3. Client Authentication . . . . . . . . . . . . . . . . . . 14
2.4. Unregistered Clients . . . . . . . . . . . . . . . . . . 15 2.3.1. Client Password . . . . . . . . . . . . . . . . . . . 15
3. Protocol Endpoints . . . . . . . . . . . . . . . . . . . . . . 15 2.3.2. Other Authentication Methods . . . . . . . . . . . . . 16
3.1. Authorization Endpoint . . . . . . . . . . . . . . . . . 15 2.4. Unregistered Clients . . . . . . . . . . . . . . . . . . 16
3.1.1. Response Type . . . . . . . . . . . . . . . . . . . . 16 3. Protocol Endpoints . . . . . . . . . . . . . . . . . . . . . . 16
3.1.2. Redirection Endpoint . . . . . . . . . . . . . . . . . 16 3.1. Authorization Endpoint . . . . . . . . . . . . . . . . . 16
3.2. Token Endpoint . . . . . . . . . . . . . . . . . . . . . 18 3.1.1. Response Type . . . . . . . . . . . . . . . . . . . . 17
3.2.1. Client Authentication . . . . . . . . . . . . . . . . 19 3.1.2. Redirection Endpoint . . . . . . . . . . . . . . . . . 18
3.3. Access Token Scope . . . . . . . . . . . . . . . . . . . 20 3.2. Token Endpoint . . . . . . . . . . . . . . . . . . . . . 20
4. Obtaining Authorization . . . . . . . . . . . . . . . . . . . 20 3.2.1. Client Authentication . . . . . . . . . . . . . . . . 20
4.1. Authorization Code . . . . . . . . . . . . . . . . . . . 20 3.3. Access Token Scope . . . . . . . . . . . . . . . . . . . 21
4.1.1. Authorization Request . . . . . . . . . . . . . . . . 22 4. Obtaining Authorization . . . . . . . . . . . . . . . . . . . 22
4.1.2. Authorization Response . . . . . . . . . . . . . . . . 23 4.1. Authorization Code Grant . . . . . . . . . . . . . . . . 22
4.1.3. Access Token Request . . . . . . . . . . . . . . . . . 25 4.1.1. Authorization Request . . . . . . . . . . . . . . . . 23
4.1.4. Access Token Response . . . . . . . . . . . . . . . . 26 4.1.2. Authorization Response . . . . . . . . . . . . . . . . 24
4.2. Implicit Grant . . . . . . . . . . . . . . . . . . . . . 26 4.1.3. Access Token Request . . . . . . . . . . . . . . . . . 26
4.2.1. Authorization Request . . . . . . . . . . . . . . . . 28 4.1.4. Access Token Response . . . . . . . . . . . . . . . . 27
4.2.2. Access Token Response . . . . . . . . . . . . . . . . 29 4.2. Implicit Grant . . . . . . . . . . . . . . . . . . . . . 28
4.3. Resource Owner Password Credentials . . . . . . . . . . . 32 4.2.1. Authorization Request . . . . . . . . . . . . . . . . 30
4.3.1. Authorization Request and Response . . . . . . . . . . 33 4.2.2. Access Token Response . . . . . . . . . . . . . . . . 31
4.3.2. Access Token Request . . . . . . . . . . . . . . . . . 33 4.3. Resource Owner Password Credentials Grant . . . . . . . . 33
4.3.3. Access Token Response . . . . . . . . . . . . . . . . 34 4.3.1. Authorization Request and Response . . . . . . . . . . 34
4.4. Client Credentials . . . . . . . . . . . . . . . . . . . 34 4.3.2. Access Token Request . . . . . . . . . . . . . . . . . 35
4.4.1. Authorization Request and Response . . . . . . . . . . 35 4.3.3. Access Token Response . . . . . . . . . . . . . . . . 36
4.4.2. Access Token Request . . . . . . . . . . . . . . . . . 35 4.4. Client Credentials Grant . . . . . . . . . . . . . . . . 36
4.4.3. Access Token Response . . . . . . . . . . . . . . . . 36 4.4.1. Authorization Request and Response . . . . . . . . . . 37
4.5. Extensions . . . . . . . . . . . . . . . . . . . . . . . 36 4.4.2. Access Token Request . . . . . . . . . . . . . . . . . 37
5. Issuing an Access Token . . . . . . . . . . . . . . . . . . . 37 4.4.3. Access Token Response . . . . . . . . . . . . . . . . 37
5.1. Successful Response . . . . . . . . . . . . . . . . . . . 37 4.5. Extension Grants . . . . . . . . . . . . . . . . . . . . 38
5.2. Error Response . . . . . . . . . . . . . . . . . . . . . 38 5. Issuing an Access Token . . . . . . . . . . . . . . . . . . . 39
6. Refreshing an Access Token . . . . . . . . . . . . . . . . . . 40 5.1. Successful Response . . . . . . . . . . . . . . . . . . . 39
7. Accessing Protected Resources . . . . . . . . . . . . . . . . 41 5.2. Error Response . . . . . . . . . . . . . . . . . . . . . 40
7.1. Access Token Types . . . . . . . . . . . . . . . . . . . 41 6. Refreshing an Access Token . . . . . . . . . . . . . . . . . . 42
8. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 42 7. Accessing Protected Resources . . . . . . . . . . . . . . . . 43
8.1. Defining Access Token Types . . . . . . . . . . . . . . . 42 7.1. Access Token Types . . . . . . . . . . . . . . . . . . . 43
8.2. Defining New Endpoint Parameters . . . . . . . . . . . . 43 8. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 44
8.3. Defining New Authorization Grant Types . . . . . . . . . 43 8.1. Defining Access Token Types . . . . . . . . . . . . . . . 44
8.4. Defining New Authorization Endpoint Response Types . . . 43 8.2. Defining New Endpoint Parameters . . . . . . . . . . . . 45
8.5. Defining Additional Error Codes . . . . . . . . . . . . . 44 8.3. Defining New Authorization Grant Types . . . . . . . . . 45
9. Native Applications . . . . . . . . . . . . . . . . . . . . . 44 8.4. Defining New Authorization Endpoint Response Types . . . 45
10. Security Considerations . . . . . . . . . . . . . . . . . . . 45 8.5. Defining Additional Error Codes . . . . . . . . . . . . . 46
10.1. Client Authentication . . . . . . . . . . . . . . . . . . 46 9. Native Applications . . . . . . . . . . . . . . . . . . . . . 46
10.2. Client Impersonation . . . . . . . . . . . . . . . . . . 46 10. Security Considerations . . . . . . . . . . . . . . . . . . . 47
10.3. Access Tokens . . . . . . . . . . . . . . . . . . . . . . 47 10.1. Client Authentication . . . . . . . . . . . . . . . . . . 48
10.4. Refresh Tokens . . . . . . . . . . . . . . . . . . . . . 47 10.2. Client Impersonation . . . . . . . . . . . . . . . . . . 48
10.5. Authorization Codes . . . . . . . . . . . . . . . . . . . 48 10.3. Access Tokens . . . . . . . . . . . . . . . . . . . . . . 49
10.6. Authorization Code Redirection URI Manipulation . . . . . 48 10.4. Refresh Tokens . . . . . . . . . . . . . . . . . . . . . 49
10.7. Resource Owner Password Credentials . . . . . . . . . . . 49 10.5. Authorization Codes . . . . . . . . . . . . . . . . . . . 50
10.8. Request Confidentiality . . . . . . . . . . . . . . . . . 50 10.6. Authorization Code Redirection URI Manipulation . . . . . 50
10.9. Endpoints Authenticity . . . . . . . . . . . . . . . . . 50 10.7. Resource Owner Password Credentials . . . . . . . . . . . 51
10.10. Credentials Guessing Attacks . . . . . . . . . . . . . . 50 10.8. Request Confidentiality . . . . . . . . . . . . . . . . . 52
10.11. Phishing Attacks . . . . . . . . . . . . . . . . . . . . 50 10.9. Endpoints Authenticity . . . . . . . . . . . . . . . . . 52
10.12. Cross-Site Request Forgery . . . . . . . . . . . . . . . 51 10.10. Credentials Guessing Attacks . . . . . . . . . . . . . . 52
10.13. Clickjacking . . . . . . . . . . . . . . . . . . . . . . 52 10.11. Phishing Attacks . . . . . . . . . . . . . . . . . . . . 52
10.14. Code Injection and Input Validation . . . . . . . . . . . 52 10.12. Cross-Site Request Forgery . . . . . . . . . . . . . . . 53
10.15. Open Redirectors . . . . . . . . . . . . . . . . . . . . 52 10.13. Clickjacking . . . . . . . . . . . . . . . . . . . . . . 54
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 53 10.14. Code Injection and Input Validation . . . . . . . . . . . 54
11.1. The OAuth Access Token Type Registry . . . . . . . . . . 53 10.15. Open Redirectors . . . . . . . . . . . . . . . . . . . . 55
11.1.1. Registration Template . . . . . . . . . . . . . . . . 53 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 55
11.2. The OAuth Parameters Registry . . . . . . . . . . . . . . 54 11.1. The OAuth Access Token Type Registry . . . . . . . . . . 55
11.2.1. Registration Template . . . . . . . . . . . . . . . . 55 11.1.1. Registration Template . . . . . . . . . . . . . . . . 56
11.2.2. Initial Registry Contents . . . . . . . . . . . . . . 55 11.2. The OAuth Parameters Registry . . . . . . . . . . . . . . 56
11.2.1. Registration Template . . . . . . . . . . . . . . . . 57
11.2.2. Initial Registry Contents . . . . . . . . . . . . . . 57
11.3. The OAuth Authorization Endpoint Response Type 11.3. The OAuth Authorization Endpoint Response Type
Registry . . . . . . . . . . . . . . . . . . . . . . . . 57 Registry . . . . . . . . . . . . . . . . . . . . . . . . 59
11.3.1. Registration Template . . . . . . . . . . . . . . . . 58 11.3.1. Registration Template . . . . . . . . . . . . . . . . 60
11.3.2. Initial Registry Contents . . . . . . . . . . . . . . 58 11.3.2. Initial Registry Contents . . . . . . . . . . . . . . 60
11.4. The OAuth Extensions Error Registry . . . . . . . . . . . 58 11.4. The OAuth Extensions Error Registry . . . . . . . . . . . 60
11.4.1. Registration Template . . . . . . . . . . . . . . . . 59 11.4.1. Registration Template . . . . . . . . . . . . . . . . 61
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 60 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 62
Appendix A. Editor's Notes . . . . . . . . . . . . . . . . . . . 60 Appendix A. Editor's Notes . . . . . . . . . . . . . . . . . . . 63
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 61 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 63
13.1. Normative References . . . . . . . . . . . . . . . . . . 61 13.1. Normative References . . . . . . . . . . . . . . . . . . 63
13.2. Informative References . . . . . . . . . . . . . . . . . 62 13.2. Informative References . . . . . . . . . . . . . . . . . 64
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 63 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 65
1. Introduction 1. Introduction
In the traditional client-server authentication model, the client In the traditional client-server authentication model, the client
requests an access restricted resource (protected resource) on the requests an access restricted resource (protected resource) on the
server by authenticating with the server using the resource owner's server by authenticating with the server using the resource owner's
credentials. In order to provide third-party applications access to credentials. In order to provide third-party applications access to
restricted resources, the resource owner shares its credentials with restricted resources, the resource owner shares its credentials with
the third-party. This creates several problems and limitations: the third-party. This creates several problems and limitations:
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o Servers are required to support password authentication, despite o Servers are required to support password authentication, despite
the security weaknesses created by passwords. the security weaknesses created by passwords.
o Third-party applications gain overly broad access to the resource o Third-party applications gain overly broad access to the resource
owner's protected resources, leaving resource owners without any owner's protected resources, leaving resource owners without any
ability to restrict duration or access to a limited subset of ability to restrict duration or access to a limited subset of
resources. resources.
o Resource owners cannot revoke access to an individual third-party o Resource owners cannot revoke access to an individual third-party
without revoking access to all third-parties, and must do so by without revoking access to all third-parties, and must do so by
changing their password. changing their password.
o Compromise of any third-party application results in compromise of o Compromise of any third-party application results in compromise of
the end-user's password and all of the data protected by that the end-user s password and all of the data protected by that
password. password.
OAuth addresses these issues by introducing an authorization layer OAuth addresses these issues by introducing an authorization layer
and separating the role of the client from that of the resource and separating the role of the client from that of the resource
owner. In OAuth, the client requests access to resources controlled owner. In OAuth, the client requests access to resources controlled
by the resource owner and hosted by the resource server, and is by the resource owner and hosted by the resource server, and is
issued a different set of credentials than those of the resource issued a different set of credentials than those of the resource
owner. owner.
Instead of using the resource owner's credentials to access protected Instead of using the resource owner's credentials to access protected
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OAuth defines four roles: OAuth defines four roles:
resource owner resource owner
An entity capable of granting access to a protected resource (e.g. An entity capable of granting access to a protected resource (e.g.
end-user). end-user).
resource server resource server
The server hosting the protected resources, capable of accepting The server hosting the protected resources, capable of accepting
and responding to protected resource requests using access tokens. and responding to protected resource requests using access tokens.
client client
An application making protected resource requests on behalf of the An application making protected resource requests on behalf of the
resource owner and with its authorization. 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 authorization server
The server issuing access tokens to the client after successfully The server issuing access tokens to the client after successfully
authenticating the resource owner and obtaining authorization. authenticating the resource owner and obtaining authorization.
The interaction between the authorization server and resource server The interaction between the authorization server and resource server
is beyond the scope of this specification. The authorization server is beyond the scope of this specification. The authorization server
may be the same server as the resource server or a separate entity. may be the same server as the resource server or a separate entity.
A single authorization server may issue access tokens accepted by A single authorization server may issue access tokens accepted by
multiple resource servers. multiple resource servers.
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1.3.2. Implicit 1.3.2. Implicit
The implicit grant is a simplified authorization code flow optimized The implicit grant is a simplified authorization code flow optimized
for clients implemented in a browser using a scripting language such for clients implemented in a browser using a scripting language such
as JavaScript. In the implicit flow, instead of issuing the client as JavaScript. In the implicit flow, instead of issuing the client
an authorization code, the client is issued an access token directly an authorization code, the client is issued an access token directly
(as the result of the resource owner authorization). The grant type (as the result of the resource owner authorization). The grant type
is implicit as no intermediate credentials (such as an authorization is implicit as no intermediate credentials (such as an authorization
code) are issued (and later used to obtain an access token). code) are issued (and later used to obtain an access token).
When issuing an implicit grant, the authorization server does not When issuing an access token during the implicit grant flow, the
authenticate the client. In some cases, the client identity can be authorization server does not authenticate the client. In some
verified via the redirection URI used to deliver the access token to cases, the client identity can be verified via the redirection URI
the client. The access token may be exposed to the resource owner or used to deliver the access token to the client. The access token may
other applications with access to the resource owner's user-agent. be exposed to the resource owner or other applications with access to
the resource owner's user-agent.
Implicit grants improve the responsiveness and efficiency of some Implicit grants improve the responsiveness and efficiency of some
clients (such as a client implemented as an in-browser application) clients (such as a client implemented as an in-browser application)
since it reduces the number of round trips required to obtain an since it reduces the number of round trips required to obtain an
access token. However, this convenience should be weighed against access token. However, this convenience should be weighed against
the security implications of using implicit grants, especially when the security implications of using implicit grants, especially when
the authorization code grant type is available. the authorization code grant type is available.
1.3.3. Resource Owner Password Credentials 1.3.3. Resource Owner Password Credentials
The resource owner password credentials (i.e. username and password) The resource owner password credentials (i.e. username and password)
can be used directly as an authorization grant to obtain an access can be used directly as an authorization grant to obtain an access
token. The credentials should only be used when there is a high token. The credentials should only be used when there is a high
degree of trust between the resource owner and the client (e.g. its degree of trust between the resource owner and the client (e.g. the
device operating system or a highly privileged application), and when client is part of the device operating system or a highly privileged
other authorization grant types are not available (such as an application), and when other authorization grant types are not
authorization code). available (such as an authorization code).
Even though this grant type requires direct client access to the Even though this grant type requires direct client access to the
resource owner credentials, the resource owner credentials are used resource owner credentials, the resource owner credentials are used
for a single request and are exchanged for an access token. This for a single request and are exchanged for an access token. This
grant type can eliminate the need for the client to store the grant type can eliminate the need for the client to store the
resource owner credentials for future use, by exchanging the resource owner credentials for future use, by exchanging the
credentials with a long-lived access token or refresh token. credentials with a long-lived access token or refresh token.
1.3.4. Client Credentials 1.3.4. Client Credentials
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this specification and are defined by companion specifications. this specification and are defined by companion specifications.
1.5. Refresh Token 1.5. Refresh Token
Refresh tokens are credentials used to obtain access tokens. Refresh Refresh tokens are credentials used to obtain access tokens. Refresh
tokens are issued to the client by the authorization server and are tokens are issued to the client by the authorization server and are
used to obtain a new access token when the current access token used to obtain a new access token when the current access token
becomes invalid or expires, or to obtain additional access tokens becomes invalid or expires, or to obtain additional access tokens
with identical or narrower scope (access tokens may have a shorter with identical or narrower scope (access tokens may have a shorter
lifetime and fewer permissions than authorized by the resource lifetime and fewer permissions than authorized by the resource
owner). Issuing a refresh token is optional. If the authorization owner). Issuing a refresh token is optional at the discretion of the
server issues a refresh token, it is included when issuing an access authorization server. If the authorization server issues a refresh
token. token, it is included when issuing an access token.
A refresh token is a string representing the authorization granted to A refresh token is a string representing the authorization granted to
the client by the resource owner. The string is usually opaque to the client by the resource owner. The string is usually opaque to
the client. The token denotes an identifier used to retrieve the the client. The token denotes an identifier used to retrieve the
authorization information. Unlike access tokens, refresh tokens are authorization information. Unlike access tokens, refresh tokens are
intended for use only with authorization servers and are never sent intended for use only with authorization servers and are never sent
to resource servers. to resource servers.
+--------+ +---------------+ +--------+ +---------------+
| |--(A)------- Authorization Grant --------->| | | |--(A)------- Authorization Grant --------->| |
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(F) Since the access token is invalid, the resource server returns (F) Since the access token is invalid, the resource server returns
an invalid token error. an invalid token error.
(G) The client requests a new access token by authenticating with (G) The client requests a new access token by authenticating with
the authorization server and presenting the refresh token. The the authorization server and presenting the refresh token. The
client authentication requirements are based on the client type client authentication requirements are based on the client type
and on the authorization server policies. and on the authorization server policies.
(H) The authorization server authenticates the client and validates (H) The authorization server authenticates the client and validates
the refresh token, and if valid issues a new access token (and the refresh token, and if valid issues a new access token (and
optionally, a new refresh token). optionally, a new refresh token).
1.6. Notational Conventions Steps C, D, E, and F are outside the scope of this specification as
described in Section 7.
1.6. TLS Version
Whenever TLS is required by this specification, the appropriate
version (or versions) of TLS will vary over time, based on the
widespread deployment and known security vulnerabilities. At the
time of this writing, TLS version 1.2 [RFC5246] is the most recent
version, but has a very limited deployment base and might not be
readily available for implementation. TLS version 1.0 [RFC2246] is
the most widely deployed version, and will provide the broadest
interoperability.
Implementations MAY also support additional transport-layer
mechanisms that meet their security requirements.
1.7. Interoperability
OAuth 2.0 provides a rich authorization framework with well-defined
security properties. However, as a rich and highly extensible
framework with many optional components, this specification is likely
to produce a wide range of non-interoperable implementations. In
addition, this specification leaves a few required components
partially or fully undefined (e.g. client registration, authorization
server capabilities, endpoint discovery).
This protocol was design with the clear expectation that future work
will define prescriptive profiles and extensions necessary to achieve
full web-scale interoperability.
1.8. Notational Conventions
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in this 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in this
specification are to be interpreted as described in [RFC2119]. specification are to be interpreted as described in [RFC2119].
This specification uses the Augmented Backus-Naur Form (ABNF) This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234]. notation of [RFC5234].
Certain security-related terms are to be understood in the sense Certain security-related terms are to be understood in the sense
defined in [RFC4949]. These terms include, but are not limited to, defined in [RFC4949]. These terms include, but are not limited to,
skipping to change at page 12, line 25 skipping to change at page 13, line 18
authenticate securely with the authorization server (i.e. ability to authenticate securely with the authorization server (i.e. ability to
maintain the confidentiality of their client credentials): maintain the confidentiality of their client credentials):
confidential confidential
Clients capable of maintaining the confidentiality of their Clients capable of maintaining the confidentiality of their
credentials (e.g. client implemented on a secure server with credentials (e.g. client implemented on a secure server with
restricted access to the client credentials), or capable of secure restricted access to the client credentials), or capable of secure
client authentication using other means. client authentication using other means.
public public
Clients incapable of maintaining the confidentiality of their Clients incapable of maintaining the confidentiality of their
credentials (e.g. clients executing on the resource owner's device credentials (e.g. clients executing on the device used by the
such as an installed native application or a web browser-based resource owner such as an installed native application or a web
application), and incapable of secure client authentication via browser-based application), and incapable of secure client
any other means. authentication via any other means.
The client type designation is based on the authorization server's The client type designation is based on the authorization server's
definition of secure authentication and its acceptable exposure definition of secure authentication and its acceptable exposure
levels of client credentials. levels of client credentials.
The authorization server SHOULD NOT make assumptions about the client
type, nor accept the type information provided by the client
developer without first establishing trust.
A client application consisting of multiple components, each with its
own client type (e.g. a distributed client with both a confidential
server-based component and a public browser-based component), MUST
register each component separately as a different client to ensure
proper handling by the authorization server. The authorization
server MAY provider tools to manage such complex clients through a
single administration interface.
This specification has been designed around the following client This specification has been designed around the following client
profiles: profiles:
web application web application
A web application is a confidential client running on a web A web application is a confidential client running on a web
server. Resource owners access the client via an HTML user server. Resource owners access the client via an HTML user
interface rendered in a user-agent on the resource owner's device. interface rendered in a user-agent on the device used by the
The client credentials as well as any access token issued to the resource owner. The client credentials as well as any access
client are stored on the web server and are not exposed to or token issued to the client are stored on the web server and are
accessible by the resource owner. not exposed to or accessible by the resource owner.
user-agent-based application user-agent-based application
A user-agent-based application is a public client in which the A user-agent-based application is a public client in which the
client code is downloaded from a web server and executes within a client code is downloaded from a web server and executes within a
user-agent (e.g. web browser) on the resource owner's device. user-agent (e.g. web browser) on the device used by the resource
Protocol data and credentials are easily accessible (and often owner. Protocol data and credentials are easily accessible (and
visible) to the resource owner. Since such applications reside often visible) to the resource owner. Since such applications
within the user-agent, they can make seamless use of the user- reside within the user-agent, they can make seamless use of the
agent capabilities when requesting authorization. user-agent capabilities when requesting authorization.
native application native application
A native application is a public client installed and executed on A native application is a public client installed and executed on
the resource owner's device. Protocol data and credentials are the device used by the resource owner. Protocol data and
accessible to the resource owner. It is assumed that any client credentials are accessible to the resource owner. It is assumed
authentication credentials included in the application can be that any client authentication credentials included in the
extracted. On the other hand, dynamically issued credentials such application can be extracted. On the other hand, dynamically
access tokens or refresh tokens can receive an acceptable level of issued credentials such as access tokens or refresh tokens can
protection. At a minimum, these credentials are protected from receive an acceptable level of protection. At a minimum, these
hostile servers which the application may interact with. On some credentials are protected from hostile servers with which the
platform these credentials might be protected from other application may interact with. On some platforms these
applications residing on the same device. credentials might be protected from other applications residing on
the same device.
2.2. Client Identifier 2.2. Client Identifier
The authorization server issues the registered client a client The authorization server issues the registered client a client
identifier - a unique string representing the registration identifier - a unique string representing the registration
information provided by the client. The client identifier is not a information provided by the client. The client identifier is not a
secret, it is exposed to the resource owner, and MUST NOT be used secret, it is exposed to the resource owner, and MUST NOT be used
alone for client authentication. alone for client authentication.
2.3. Client Authentication 2.3. Client Authentication
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If the client type is confidential, the client and authorization If the client type is confidential, the client and authorization
server establish a client authentication method suitable for the server establish a client authentication method suitable for the
security requirements of the authorization server. The authorization security requirements of the authorization server. The authorization
server MAY accept any form of client authentication meeting its server MAY accept any form of client authentication meeting its
security requirements. security requirements.
Confidential clients are typically issued (or establish) a set of Confidential clients are typically issued (or establish) a set of
client credentials used for authenticating with the authorization client credentials used for authenticating with the authorization
server (e.g. password, public/private key pair). server (e.g. password, public/private key pair).
The authorization server SHOULD NOT make assumptions about the client The authorization server MAY establish a client authentication method
type or accept the type information provided without establishing with public clients. However, the authorization server MUST NOT rely
trust with the client or its developer. The authorization server MAY on public client authentication for the purpose of identifying the
establish a client authentication method with public clients. client.
However, the authorization server MUST NOT rely on public client
authentication for the purpose of identifying the client.
The client MUST NOT use more than one authentication method in each The client MUST NOT use more than one authentication method in each
request. request.
2.3.1. Client Password 2.3.1. Client Password
Clients in possession of a client password MAY use the HTTP Basic Clients in possession of a client password MAY use the HTTP Basic
authentication scheme as defined in [RFC2617] to authenticate with authentication scheme as defined in [RFC2617] to authenticate with
the authorization server. The client identifier is used as the the authorization server. The client identifier is used as the
username, and the client password is used as the password. username, and the client password is used as the password. The
authorization server MUST support the HTTP Basic authentication
scheme for authenticating clients which were issued a client
password.
For example (extra line breaks are for display purposes only): For example (extra line breaks are for display purposes only):
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
Alternatively, the authorization server MAY allow including the Alternatively, the authorization server MAY support including the
client credentials in the request body using the following client credentials in the request body using the following
parameters: parameters:
client_id client_id
REQUIRED. The client identifier issued to the client during REQUIRED. The client identifier issued to the client during
the registration process described by Section 2.2. the registration process described by Section 2.2.
client_secret client_secret
REQUIRED. The client secret. The client MAY omit the REQUIRED. The client secret. The client MAY omit the
parameter if the client secret is an empty string. parameter if the client secret is an empty string.
Including the client credentials in the request body using the two Including the client credentials in the request body using the two
parameters is NOT RECOMMENDED, and should be limited to clients parameters is NOT RECOMMENDED, and should be limited to clients
unable to directly utilize the HTTP Basic authentication scheme (or unable to directly utilize the HTTP Basic authentication scheme (or
other password-based HTTP authentication schemes). other password-based HTTP authentication schemes). The parameters
can only be transmitted in the request body and MUST NOT be included
in the request URI.
For example, requesting to refresh an access token (Section 6) using For example, requesting to refresh an access token (Section 6) using
the body parameters (extra line breaks are for display purposes the body parameters (extra line breaks are for display purposes
only): only):
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/x-www-form-urlencoded;charset=UTF-8 Content-Type: application/x-www-form-urlencoded;charset=UTF-8
grant_type=refresh_token&refresh_token=tGzv3JOkF0XG5Qx2TlKWIA grant_type=refresh_token&refresh_token=tGzv3JOkF0XG5Qx2TlKWIA
&client_id=s6BhdRkqt3&client_secret=7Fjfp0ZBr1KtDRbnfVdmIw &client_id=s6BhdRkqt3&client_secret=7Fjfp0ZBr1KtDRbnfVdmIw
The authorization server MUST require the use of a transport-layer The authorization server MUST require TLS as described in Section 1.6
security mechanism when sending requests to the token endpoint, as when sending requests using password authentication.
requests using this authentication method result in the transmission
of clear-text credentials.
Since this client authentication method involves a password, the Since this client authentication method involves a password, the
authorization server MUST protect any endpoint utilizing it against authorization server MUST protect any endpoint utilizing it against
brute force attacks. brute force attacks.
2.3.2. Other Authentication Methods 2.3.2. Other Authentication Methods
The authorization server MAY support any suitable HTTP authentication The authorization server MAY support any suitable HTTP authentication
scheme matching its security requirements. When using other scheme matching its security requirements. When using other
authentication methods, the authorization server MUST define a authentication methods, the authorization server MUST define a
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2.4. Unregistered Clients 2.4. Unregistered Clients
This specification does not exclude the use of unregistered clients. This specification does not exclude the use of unregistered clients.
However, the use with such clients is beyond the scope of this However, the use with such clients is beyond the scope of this
specification, and requires additional security analysis and review specification, and requires additional security analysis and review
of its interoperability impact. of its interoperability impact.
3. Protocol Endpoints 3. Protocol Endpoints
The authorization process utilizes two endpoints (HTTP resources): The authorization process utilizes two authorization server endpoints
(HTTP resources):
o Authorization endpoint - used to obtain authorization from the o Authorization endpoint - used to obtain authorization from the
resource owner via user-agent redirection. resource owner via user-agent redirection.
o Token endpoint - used to exchange an authorization grant for an o Token endpoint - used to exchange an authorization grant for an
access token, typically with client authentication. access token, typically with client authentication.
As well as one client endpoint:
o Redirection endpoint - used to return authorization credentials
responses from the authorization server to the client via the
resource owner user-agent.
Not every authorization grant type utilizes both endpoints. Not every authorization grant type utilizes both endpoints.
Extension grant types MAY define additional endpoints as needed. Extension grant types MAY define additional endpoints as needed.
3.1. Authorization Endpoint 3.1. Authorization Endpoint
The authorization endpoint is used to interact with the resource The authorization endpoint is used to interact with the resource
owner and obtain an authorization grant. The authorization server owner and obtain an authorization grant. The authorization server
MUST first verify the identity of the resource owner. The way in MUST first verify the identity of the resource owner. The way in
which the authorization server authenticates the resource owner (e.g. which the authorization server authenticates the resource owner (e.g.
username and password login, session cookies) is beyond the scope of username and password login, session cookies) is beyond the scope of
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authorization endpoint are beyond the scope of this specification, authorization endpoint are beyond the scope of this specification,
but the location is typically provided in the service documentation. but the location is typically provided in the service documentation.
The endpoint URI MAY include an "application/x-www-form-urlencoded" The endpoint URI MAY include an "application/x-www-form-urlencoded"
formatted ([W3C.REC-html401-19991224]) query component ([RFC3986] formatted ([W3C.REC-html401-19991224]) query component ([RFC3986]
section 3.4), which MUST be retained when adding additional query section 3.4), which MUST be retained when adding additional query
parameters. The endpoint URI MUST NOT include a fragment component. parameters. The endpoint URI MUST NOT include a fragment component.
Since requests to the authorization endpoint result in user Since requests to the authorization endpoint result in user
authentication and the transmission of clear-text credentials (in the authentication and the transmission of clear-text credentials (in the
HTTP response), the authorization server MUST require the use of a HTTP response), the authorization server MUST require TLS as
transport-layer security mechanism when sending requests to the described in Section 1.6 when sending requests to the authorization
authorization endpoint. The authorization server MUST support TLS endpoint.
1.0 ([RFC2246]), SHOULD support TLS 1.2 ([RFC5246]) and its future
replacements, and MAY support additional transport-layer mechanisms
meeting its security requirements.
The authorization server MUST support the use of the HTTP "GET" The authorization server MUST support the use of the HTTP "GET"
method [RFC2616] for the authorization endpoint, and MAY support the method [RFC2616] for the authorization endpoint, and MAY support the
use of the "POST" method as well. use of the "POST" method as well.
Parameters sent without a value MUST be treated as if they were Parameters sent without a value MUST be treated as if they were
omitted from the request. The authorization server SHOULD ignore omitted from the request. The authorization server MUST ignore
unrecognized request parameters. Request and response parameters unrecognized request parameters. Request and response parameters
MUST NOT be included more than once. MUST NOT be included more than once.
3.1.1. Response Type 3.1.1. Response Type
The authorization endpoint is used by the authorization code grant The authorization endpoint is used by the authorization code grant
type and implicit grant type flows. The client informs the type and implicit grant type flows. The client informs the
authorization server of the desired grant type using the following authorization server of the desired grant type using the following
parameter: parameter:
response_type response_type
REQUIRED. The value MUST be one of "code" for requesting an REQUIRED. The value MUST be one of "code" for requesting an
authorization code as described by Section 4.1.1, "token" for authorization code as described by Section 4.1.1, "token" for
requesting an access token (implicit grant) as described by requesting an access token (implicit grant) as described by
Section 4.2.1, or a registered extension value as described by Section 4.2.1, or a registered extension value as described by
Section 8.4. If the response type contains one or more space Section 8.4.
characters (%x20), it is interpreted as a space-delimited list
of values, where the order of values does not matter (e.g. "a Extension response types MAY contain a space-delimited (%x20) list of
b" is the same as "b a"). 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.
If an authorization request is missing the "response_type" parameter, If an authorization request is missing the "response_type" parameter,
the authorization server SHOULD return an error response as described the authorization server MUST return an error response as described
in Section 4.1.2.1. in Section 4.1.2.1.
3.1.2. Redirection Endpoint 3.1.2. Redirection Endpoint
After completing its interaction with the resource owner, the After completing its interaction with the resource owner, the
authorization server directs the resource owner's user-agent back to authorization server directs the resource owner's user-agent back to
the client. The authorization server redirects the user-agent to the the client. The authorization server redirects the user-agent to the
client's redirection endpoint previously established with the client's redirection endpoint previously established with the
authorization server during the client registration process or when authorization server during the client registration process or when
making the authorization request. making the authorization request.
The redirection endpoint URI MUST be an absolute URI as defined by The redirection endpoint URI MUST be an absolute URI as defined by
[RFC3986] section 4.3. The endpoint URI MAY include an [RFC3986] section 4.3. The endpoint URI MAY include an
"application/x-www-form-urlencoded" formatted "application/x-www-form-urlencoded" formatted
([W3C.REC-html401-19991224]) query component ([RFC3986] section 3.4), ([W3C.REC-html401-19991224]) query component ([RFC3986] section 3.4),
which MUST be retained when adding additional query parameters. The which MUST be retained when adding additional query parameters. The
endpoint URI MUST NOT include a fragment component. endpoint URI MUST NOT include a fragment component.
3.1.2.1. Endpoint Request Confidentiality 3.1.2.1. Endpoint Request Confidentiality
If a redirection request will result in the transmission of an The redirection endpoint SHOULD require the use of TLS as described
authorization code or access token over an open network (between the in Section 1.6 when the requested response type is "code" or "token",
resource owner's user-agent and the client), the client SHOULD or when the redirection request will result in the transmission of
require the use of a transport-layer security mechanism. sensitive credentials over an open network. This specification does
not mandate the use of TLS because at the time of this writing,
requiring clients to deploy TLS is a significant hurdle for most
client developers.
Lack of transport-layer security can have a severe impact on the Lack of transport-layer security can have a severe impact on the
security of the client and the protected resources it is authorized security of the client and the protected resources it is authorized
to access. The use of transport-layer security is particularly to access. The use of transport-layer security is particularly
critical when the authorization process is used as a form of critical when the authorization process is used as a form of
delegated end-user authentication by the client (e.g. third-party delegated end-user authentication by the client (e.g. third-party
sign-in service). sign-in service).
3.1.2.2. Registration Requirements 3.1.2.2. Registration Requirements
The authorization server SHOULD require all clients to register their The authorization server MUST require the following clients to
redirection URI prior to using the authorization endpoint, and MUST register their redirection endpoint:
require the following clients to register their redirection URI:
o Public clients. o Public clients.
o Confidential clients utilizing the implicit grant type. o Confidential clients utilizing the implicit grant type.
The authorization server SHOULD require all clients to register their
redirection endpoint prior to utilizing the authorization endpoint
The authorization server SHOULD require the client to provide the The authorization server SHOULD require the client to provide the
complete redirection URI (the client MAY use the "state" request complete redirection URI (the client MAY use the "state" request
parameter to achieve per-request customization). The authorization parameter to achieve per-request customization). If requiring the
server MAY allow the client to register multiple redirection URIs. registration of the complete redirection URI is not possible, the
If requiring the registration of the complete redirection URI is not authorization server SHOULD require the registration of the URI
possible, the authorization server SHOULD require the registration of scheme, authority, and path (allowing the client to dynamically vary
the URI scheme, authority, and path (allowing the client to only the query component of the redirection URI when requesting
dynamically change only the query component of the redirection URI authorization).
when requesting authorization).
The authorization server MAY allow the client to register multiple
redirection endpoints.
Lack of a redirection URI registration requirement can enable an
attacker to use the authorization endpoint as open redirector as
described in Section 10.15.
3.1.2.3. Dynamic Configuration 3.1.2.3. Dynamic Configuration
If multiple redirection URIs have been registered, if only part of If multiple redirection URIs have been registered, if only part of
the redirection URI has been registered, or if no redirection URI has the redirection URI has been registered, or if no redirection URI has
been registered, the client MUST include a redirection URI with the been registered, the client MUST include a redirection URI with the
authorization request using the "redirect_uri" request parameter. authorization request using the "redirect_uri" request parameter.
When a redirection URI is included in an authorization request, the When a redirection URI is included in an authorization request, the
authorization server MUST compare and match the value received authorization server MUST compare and match the value received
against at least one of the registered redirection URIs (or URI against at least one of the registered redirection URIs (or URI
components) as defined in [RFC3986] section 6, if any redirection components) as defined in [RFC3986] section 6, if any redirection
URIs were registered. If the client registration included the full URIs were registered. If the client registration included the full
redirection URI, the authorization server MUST compare the two URIs redirection URI, the authorization server MUST compare the two URIs
using simple string comparison as defined in [RFC3986] section 6.2.1. using simple string comparison as defined in [RFC3986] section 6.2.1.
If the authorization server allows the client to dynamically change
the query component of the redirection URI, the client MUST ensure
that manipulation of the query component by an attacker cannot lead
to an abuse of the redirection endpoint as described in
Section 10.15.
3.1.2.4. Invalid Endpoint 3.1.2.4. Invalid Endpoint
If an authorization request fails validation due to a missing, If an authorization request fails validation due to a missing,
invalid, or mismatching redirection URI, the authorization server invalid, or mismatching redirection URI, the authorization server
SHOULD inform the resource owner of the error, and MUST NOT SHOULD inform the resource owner of the error, and MUST NOT
automatically redirect the user-agent to the invalid redirection URI. automatically redirect the user-agent to the invalid redirection URI.
The authorization server SHOULD NOT redirect the user-agent to
unregistered or untrusted URIs to prevent the authorization endpoint
from being used as an open redirector.
3.1.2.5. Endpoint Content 3.1.2.5. Endpoint Content
The redirection request to the client's endpoint typically results in The redirection request to the client's endpoint typically results in
an HTML document response, processed by the user-agent. If the HTML an HTML document response, processed by the user-agent. If the HTML
response is served directly as the result of the redirection request, response is served directly as the result of the redirection request,
any script included in the HTML document will execute with full any script included in the HTML document will execute with full
access to the redirection URI and the credentials it contains. access to the redirection URI and the credentials it contains.
The client MUST NOT include any untrusted third-party scripts in the The client MUST NOT include any untrusted third-party scripts in the
redirection endpoint response (e.g. third-party analytics, social redirection endpoint response (e.g. third-party analytics, social
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endpoint are beyond the scope of this specification but is typically endpoint are beyond the scope of this specification but is typically
provided in the service documentation. provided in the service documentation.
The endpoint URI MAY include an "application/x-www-form-urlencoded" The endpoint URI MAY include an "application/x-www-form-urlencoded"
formatted ([W3C.REC-html401-19991224]) query component ([RFC3986] formatted ([W3C.REC-html401-19991224]) query component ([RFC3986]
section 3.4), which MUST be retained when adding additional query section 3.4), which MUST be retained when adding additional query
parameters. The endpoint URI MUST NOT include a fragment component. parameters. The endpoint URI MUST NOT include a fragment component.
Since requests to the token endpoint result in the transmission of Since requests to the token endpoint result in the transmission of
clear-text credentials (in the HTTP request and response), the clear-text credentials (in the HTTP request and response), the
authorization server MUST require the use of a transport-layer authorization server MUST require TLS as described in Section 1.6
security mechanism when sending requests to the token endpoint. The when sending requests to the token endpoint.
authorization server MUST support TLS 1.0 ([RFC2246]), SHOULD support
TLS 1.2 ([RFC5246]) and its future replacements, and MAY support
additional transport-layer mechanisms meeting its security
requirements.
The client MUST use the HTTP "POST" method when making access token The client MUST use the HTTP "POST" method when making access token
requests. requests.
Parameters sent without a value MUST be treated as if they were Parameters sent without a value MUST be treated as if they were
omitted from the request. The authorization server SHOULD ignore omitted from the request. The authorization server MUST ignore
unrecognized request parameters. Request and response parameters unrecognized request parameters. Request and response parameters
MUST NOT be included more than once. MUST NOT be included more than once.
3.2.1. Client Authentication 3.2.1. Client Authentication
Confidential clients, clients issued client credentials, or clients Confidential clients or other clients issued client credentials MUST
assigned other authentication requirements MUST authenticate with the authenticate with the authorization server as described in
authorization server as described in Section 2.3 when making requests Section 2.3 when making requests to the token endpoint. Client
to the token endpoint. Client authentication is used for: authentication is used for:
o Enforcing the binding of refresh tokens and authorization codes to o Enforcing the binding of refresh tokens and authorization codes to
the client they are issued. Client authentication is critical the client they were issued to. Client authentication is critical
when an authorization code is transmitted to the redirection when an authorization code is transmitted to the redirection
endpoint over an insecure channel, or when the redirection URI has endpoint over an insecure channel, or when the redirection URI has
not been registered in full. not been registered in full.
o Recovering from a compromised client by disabling the client or o Recovering from a compromised client by disabling the client or
changing its credentials, thus preventing an attacker from abusing changing its credentials, thus preventing an attacker from abusing
stolen refresh tokens. Changing a single set of client stolen refresh tokens. Changing a single set of client
credentials is significantly faster than revoking an entire set of credentials is significantly faster than revoking an entire set of
refresh tokens. refresh tokens.
o Implementing authentication management best practices which o Implementing authentication management best practices which
require periodic credential rotation. Rotation of an entire set require periodic credential rotation. Rotation of an entire set
of refresh tokens can be challenging, while rotation of a single of refresh tokens can be challenging, while rotation of a single
set of client credentials is significantly easier. set of client credentials is significantly easier.
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refresh tokens. refresh tokens.
o Implementing authentication management best practices which o Implementing authentication management best practices which
require periodic credential rotation. Rotation of an entire set require periodic credential rotation. Rotation of an entire set
of refresh tokens can be challenging, while rotation of a single of refresh tokens can be challenging, while rotation of a single
set of client credentials is significantly easier. set of client credentials is significantly easier.
A public client that was not issued a client password MAY use the A public client that was not issued a client password MAY use the
"client_id" request parameter to identify itself when sending "client_id" request parameter to identify itself when sending
requests to the token endpoint. requests to the token endpoint.
The security ramifications of allowing unauthenticated access by
public clients to the token endpoint, as well as the issuance of
refresh tokens to public clients MUST be taken into consideration.
3.3. Access Token Scope 3.3. Access Token Scope
The authorization and token endpoints allow the client to specify the The authorization and token endpoints allow the client to specify the
scope of the access request using the "scope" request parameter. In scope of the access request using the "scope" request parameter. In
turn, the authorization server uses the "scope" response parameter to turn, the authorization server uses the "scope" response parameter to
inform the client of the scope of the access token issued. inform the client of the scope of the access token issued.
The value of the scope parameter is expressed as a list of space- The value of the scope parameter is expressed as a list of space-
delimited, case sensitive strings. The strings are defined by the delimited, case sensitive strings. The strings are defined by the
authorization server. If the value contains multiple space-delimited authorization server. If the value contains multiple space-delimited
strings, their order does not matter, and each string adds an strings, their order does not matter, and each string adds an
additional access range to the requested scope. 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 The authorization server MAY fully or partially ignore the scope
requested by the client based on the authorization server policy or requested by the client based on the authorization server policy or
the resource owner's instructions. If the issued access token scope the resource owner's instructions. If the issued access token scope
is different from the one requested by the client, the authorization is different from the one requested by the client, the authorization
server SHOULD include the "scope" response parameter to inform the server MUST include the "scope" response parameter to inform the
client of the actual scope granted. client of the actual scope granted.
If the client omits the scope parameter when requesting
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).
4. Obtaining Authorization 4. Obtaining Authorization
To request an access token, the client obtains authorization from the To request an access token, the client obtains authorization from the
resource owner. The authorization is expressed in the form of an resource owner. The authorization is expressed in the form of an
authorization grant which the client uses to request the access authorization grant which the client uses to request the access
token. OAuth defines four grant types: authorization code, implicit, token. OAuth defines four grant types: authorization code, implicit,
resource owner password credentials, and client credentials. It also resource owner password credentials, and client credentials. It also
provides an extension mechanism for defining additional grant types. provides an extension mechanism for defining additional grant types.
4.1. Authorization Code 4.1. Authorization Code Grant
The authorization code grant type is used to obtain both access The authorization code grant type is used to obtain both access
tokens and refresh tokens and is optimized for confidential clients. tokens and refresh tokens and is optimized for confidential clients.
As a redirection-based flow, the client must be capable of As a redirection-based flow, the client must be capable of
interacting with the resource owner's user-agent (typically a web interacting with the resource owner's user-agent (typically a web
browser) and capable of receiving incoming requests (via redirection) browser) and capable of receiving incoming requests (via redirection)
from the authorization server. from the authorization server.
+----------+ +----------+
| resource | | resource |
skipping to change at page 21, line 31 skipping to change at page 22, line 49
(A) (C) | | (A) (C) | |
| | | | | | | |
^ v | | ^ v | |
+---------+ | | +---------+ | |
| |>---(D)-- Authorization Code ---------' | | |>---(D)-- Authorization Code ---------' |
| Client | & Redirection URI | | Client | & Redirection URI |
| | | | | |
| |<---(E)----- Access Token -------------------' | |<---(E)----- Access Token -------------------'
+---------+ (w/ Optional Refresh Token) +---------+ (w/ Optional Refresh Token)
Note: The lines illustrating steps A, B, and C are broken into two
parts as they pass through the user-agent.
Figure 3: Authorization Code Flow Figure 3: Authorization Code Flow
The flow illustrated in Figure 3 includes the following steps: The flow illustrated in Figure 3 includes the following steps:
(A) The client initiates the flow by directing the resource owner's (A) The client initiates the flow by directing the resource owner's
user-agent to the authorization endpoint. The client includes user-agent to the authorization endpoint. The client includes
its client identifier, requested scope, local state, and a its client identifier, requested scope, local state, and a
redirection URI to which the authorization server will send the redirection URI to which the authorization server will send the
user-agent back once access is granted (or denied). user-agent back once access is granted (or denied).
(B) The authorization server authenticates the resource owner (via (B) The authorization server authenticates the resource owner (via
skipping to change at page 22, line 15 skipping to change at page 23, line 33
(D) The client requests an access token from the authorization (D) The client requests an access token from the authorization
server's token endpoint by including the authorization code server's token endpoint by including the authorization code
received in the previous step. When making the request, the received in the previous step. When making the request, the
client authenticates with the authorization server. The client client authenticates with the authorization server. The client
includes the redirection URI used to obtain the authorization includes the redirection URI used to obtain the authorization
code for verification. code for verification.
(E) The authorization server authenticates the client, validates the (E) The authorization server authenticates the client, validates the
authorization code, and ensures the redirection URI received authorization code, and ensures the redirection URI received
matches the URI used to redirect the client in step (C). If matches the URI used to redirect the client in step (C). If
valid, the authorization server responds back with an access valid, the authorization server responds back with an access
token and optional refresh token. token and optionally, a refresh token.
4.1.1. Authorization Request 4.1.1. Authorization Request
The client constructs the request URI by adding the following The client constructs the request URI by adding the following
parameters to the query component of the authorization endpoint URI parameters to the query component of the authorization endpoint URI
using the "application/x-www-form-urlencoded" format as defined by using the "application/x-www-form-urlencoded" format as defined by
[W3C.REC-html401-19991224]: [W3C.REC-html401-19991224]:
response_type response_type
REQUIRED. Value MUST be set to "code". REQUIRED. Value MUST be set to "code".
client_id client_id
REQUIRED. The client identifier as described in Section 2.2. REQUIRED. The client identifier as described in Section 2.2.
redirect_uri redirect_uri
OPTIONAL, as described in Section 3.1.2. OPTIONAL. As described in Section 3.1.2.
scope scope
OPTIONAL. The scope of the access request as described by OPTIONAL. The scope of the access request as described by
Section 3.3. Section 3.3.
state state
RECOMMENDED. An opaque value used by the client to maintain RECOMMENDED. An opaque value used by the client to maintain
state between the request and callback. The authorization state between the request and callback. The authorization
server includes this value when redirecting the user-agent back server includes this value when redirecting the user-agent back
to the client. The parameter SHOULD be used for preventing to the client. The parameter SHOULD be used for preventing
cross-site request forgery as described in Section 10.12. cross-site request forgery as described in Section 10.12.
The client directs the resource owner to the constructed URI using an The client directs the resource owner to the constructed URI using an
HTTP redirection response, or by other means available to it via the HTTP redirection response, or by other means available to it via the
user-agent. user-agent.
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state between the request and callback. The authorization state between the request and callback. The authorization
server includes this value when redirecting the user-agent back server includes this value when redirecting the user-agent back
to the client. The parameter SHOULD be used for preventing to the client. The parameter SHOULD be used for preventing
cross-site request forgery as described in Section 10.12. cross-site request forgery as described in Section 10.12.
The client directs the resource owner to the constructed URI using an The client directs the resource owner to the constructed URI using an
HTTP redirection response, or by other means available to it via the HTTP redirection response, or by other means available to it via the
user-agent. user-agent.
For example, the client directs the user-agent to make the following For example, the client directs the user-agent to make the following
HTTP request using transport-layer security (extra line breaks are HTTP request using TLS (extra line breaks are for display purposes
for display purposes only): only):
GET /authorize?response_type=code&client_id=s6BhdRkqt3&state=xyz GET /authorize?response_type=code&client_id=s6BhdRkqt3&state=xyz
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb HTTP/1.1 &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb HTTP/1.1
Host: server.example.com Host: server.example.com
The authorization server validates the request to ensure all required The authorization server validates the request to ensure all required
parameters are present and valid. If the request is valid, the parameters are present and valid. If the request is valid, the
authorization server authenticates the resource owner and obtains an authorization server authenticates the resource owner and obtains an
authorization decision (by asking the resource owner or by authorization decision (by asking the resource owner or by
establishing approval via other means). establishing approval via other means).
skipping to change at page 23, line 31 skipping to change at page 24, line 50
redirection URI using the "application/x-www-form-urlencoded" format: redirection URI using the "application/x-www-form-urlencoded" format:
code code
REQUIRED. The authorization code generated by the REQUIRED. The authorization code generated by the
authorization server. The authorization code MUST expire authorization server. The authorization code MUST expire
shortly after it is issued to mitigate the risk of leaks. A shortly after it is issued to mitigate the risk of leaks. A
maximum authorization code lifetime of 10 minutes is maximum authorization code lifetime of 10 minutes is
RECOMMENDED. The client MUST NOT use the authorization code RECOMMENDED. The client MUST NOT use the authorization code
more than once. If an authorization code is used more than more than once. If an authorization code is used more than
once, the authorization server MUST deny the request and SHOULD once, the authorization server MUST deny the request and SHOULD
attempt to revoke all tokens previously issued based on that revoke (when possible) all tokens previously issued based on
authorization code. The authorization code is bound to the that authorization code. The authorization code is bound to
client identifier and redirection URI. the client identifier and redirection URI.
state state
REQUIRED if the "state" parameter was present in the client REQUIRED if the "state" parameter was present in the client
authorization request. The exact value received from the authorization request. The exact value received from the
client. client.
For example, the authorization server redirects the user-agent by For example, the authorization server redirects the user-agent by
sending the following HTTP response: sending the following HTTP response:
HTTP/1.1 302 Found HTTP/1.1 302 Found
Location: https://client.example.com/cb?code=SplxlOBeZQQYbYS6WxSbIA Location: https://client.example.com/cb?code=SplxlOBeZQQYbYS6WxSbIA
&state=xyz &state=xyz
The client SHOULD ignore unrecognized response parameters. The The client MUST ignore unrecognized response parameters. The
authorization code string size is left undefined by this authorization code string size is left undefined by this
specification. The client should avoid making assumptions about code specification. The client should avoid making assumptions about code
value sizes. The authorization server should document the size of value sizes. The authorization server should document the size of
any value it issues. any value it issues.
4.1.2.1. Error Response 4.1.2.1. Error Response
If the request fails due to a missing, invalid, or mismatching If the request fails due to a missing, invalid, or mismatching
redirection URI, or if the client identifier provided is invalid, the redirection URI, or if the client identifier is missing or invalid,
authorization server SHOULD inform the resource owner of the error, the authorization server SHOULD inform the resource owner of the
and MUST NOT automatically redirect the user-agent to the invalid error, and MUST NOT automatically redirect the user-agent to the
redirection URI. invalid redirection URI.
If the resource owner denies the access request or if the request If the resource owner denies the access request or if the request
fails for reasons other than a missing or invalid redirection URI, fails for reasons other than a missing or invalid redirection URI,
the authorization server informs the client by adding the following the authorization server informs the client by adding the following
parameters to the query component of the redirection URI using the parameters to the query component of the redirection URI using the
"application/x-www-form-urlencoded" format: "application/x-www-form-urlencoded" format:
error error
REQUIRED. A single error code from the following: REQUIRED. A single error code from the following:
invalid_request invalid_request
The request is missing a required parameter, includes an The request is missing a required parameter, includes an
unsupported parameter value, or is otherwise malformed. invalid parameter value, or is otherwise malformed.
unauthorized_client unauthorized_client
The client is not authorized to request an authorization The client is not authorized to request an authorization
code using this method. code using this method.
access_denied access_denied
The resource owner or authorization server denied the The resource owner or authorization server denied the
request. request.
unsupported_response_type unsupported_response_type
The authorization server does not support obtaining an The authorization server does not support obtaining an
authorization code using this method. authorization code using this method.
invalid_scope invalid_scope
The requested scope is invalid, unknown, or malformed. The requested scope is invalid, unknown, or malformed.
server_error server_error
The authorization server encountered an unexpected The authorization server encountered an unexpected
skipping to change at page 25, line 4 skipping to change at page 26, line 28
the request due to a temporary overloading or maintenance the request due to a temporary overloading or maintenance
of the server. of the server.
error_description error_description
OPTIONAL. A human-readable UTF-8 encoded text providing OPTIONAL. A human-readable UTF-8 encoded text providing
additional information, used to assist the client developer in additional information, used to assist the client developer in
understanding the error that occurred. understanding the error that occurred.
error_uri error_uri
OPTIONAL. A URI identifying a human-readable web page with OPTIONAL. A URI identifying a human-readable web page with
information about the error, used to provide the client information about the error, used to provide the client
developer with additional information about the error. developer with additional information about the error.
state state
REQUIRED if a valid "state" parameter was present in the client REQUIRED if a "state" parameter was present in the client
authorization request. The exact value received from the authorization request. The exact value received from the
client. client.
For example, the authorization server redirects the user-agent by For example, the authorization server redirects the user-agent by
sending the following HTTP response: sending the following HTTP response:
HTTP/1.1 302 Found HTTP/1.1 302 Found
Location: https://client.example.com/cb?error=access_denied&state=xyz Location: https://client.example.com/cb?error=access_denied&state=xyz
4.1.3. Access Token Request 4.1.3. Access Token Request
skipping to change at page 25, line 37 skipping to change at page 27, line 18
redirect_uri redirect_uri
REQUIRED, if the "redirect_uri" parameter was included in the REQUIRED, if the "redirect_uri" parameter was included in the
authorization request as described in Section 4.1.1, and their authorization request as described in Section 4.1.1, and their
values MUST be identical. values MUST be identical.
If the client type is confidential or the client was issued client If the client type is confidential or the client was issued client
credentials (or assigned other authentication requirements), the credentials (or assigned other authentication requirements), the
client MUST authenticate with the authorization server as described client MUST authenticate with the authorization server as described
in Section 3.2.1. in Section 3.2.1.
For example, the client makes the following HTTP request using For example, the client makes the following HTTP request using TLS
transport-layer security (extra line breaks are for display purposes (extra line breaks are for display purposes only):
only):
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
Content-Type: application/x-www-form-urlencoded;charset=UTF-8 Content-Type: application/x-www-form-urlencoded;charset=UTF-8
grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
The authorization server MUST: The authorization server MUST:
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from the authorization server. from the authorization server.
Unlike the authorization code grant type in which the client makes Unlike the authorization code grant type in which the client makes
separate requests for authorization and access token, the client separate requests for authorization and access token, the client
receives the access token as the result of the authorization request. receives the access token as the result of the authorization request.
The implicit grant type does not include client authentication, and The implicit grant type does not include client authentication, and
relies on the presence of the resource owner and the registration of relies on the presence of the resource owner and the registration of
the redirection URI. Because the access token is encoded into the the redirection URI. Because the access token is encoded into the
redirection URI, it may be exposed to the resource owner and other redirection URI, it may be exposed to the resource owner and other
applications residing on its device. applications residing on the same device.
+----------+ +----------+
| Resource | | Resource |
| Owner | | Owner |
| | | |
+----------+ +----------+
^ ^
| |
(B) (B)
+----|-----+ Client Identifier +---------------+ +----|-----+ Client Identifier +---------------+
skipping to change at page 28, line 4 skipping to change at page 29, line 37
+-|--------+ +-|--------+
| | | |
(A) (G) Access Token (A) (G) Access Token
| | | |
^ v ^ v
+---------+ +---------+
| | | |
| Client | | Client |
| | | |
+---------+ +---------+
Note: The lines illustrating steps A and B are broken into two parts
as they pass through the user-agent.
Figure 4: Implicit Grant Flow Figure 4: Implicit Grant Flow
The flow illustrated in Figure 4 includes the following steps: The flow illustrated in Figure 4 includes the following steps:
(A) The client initiates the flow by directing the resource owner's (A) The client initiates the flow by directing the resource owner's
user-agent to the authorization endpoint. The client includes user-agent to the authorization endpoint. The client includes
its client identifier, requested scope, local state, and a its client identifier, requested scope, local state, and a
redirection URI to which the authorization server will send the redirection URI to which the authorization server will send the
user-agent back once access is granted (or denied). user-agent back once access is granted (or denied).
(B) The authorization server authenticates the resource owner (via (B) The authorization server authenticates the resource owner (via
the user-agent) and establishes whether the resource owner the user-agent) and establishes whether the resource owner
grants or denies the client's access request. grants or denies the client's access request.
(C) Assuming the resource owner grants access, the authorization (C) Assuming the resource owner grants access, the authorization
server redirects the user-agent back to the client using the server redirects the user-agent back to the client using the
redirection URI provided earlier. The redirection URI includes redirection URI provided earlier. The redirection URI includes
the access token in the URI fragment. the access token in the URI fragment.
(D) The user-agent follows the redirection instructions by making a (D) The user-agent follows the redirection instructions by making a
request to the web-hosted client resource (which does not request to the web-hosted client resource (which does not
include the fragment). The user-agent retains the fragment include the fragment per [RFC2616]). The user-agent retains the
information locally. fragment information locally.
(E) The web-hosted client resource returns a web page (typically an (E) The web-hosted client resource returns a web page (typically an
HTML document with an embedded script) capable of accessing the HTML document with an embedded script) capable of accessing the
full redirection URI including the fragment retained by the full redirection URI including the fragment retained by the
user-agent, and extracting the access token (and other user-agent, and extracting the access token (and other
parameters) contained in the fragment. parameters) contained in the fragment.
(F) The user-agent executes the script provided by the web-hosted (F) The user-agent executes the script provided by the web-hosted
client resource locally, which extracts the access token and client resource locally, which extracts the access token and
passes it to the client. passes it to the client.
4.2.1. Authorization Request 4.2.1. Authorization Request
The client constructs the request URI by adding the following The client constructs the request URI by adding the following
parameters to the query component of the authorization endpoint URI parameters to the query component of the authorization endpoint URI
using the "application/x-www-form-urlencoded" format: using the "application/x-www-form-urlencoded" format:
response_type response_type
REQUIRED. Value MUST be set to "token". REQUIRED. Value MUST be set to "token".
client_id client_id
REQUIRED. The client identifier as described in Section 2.2. REQUIRED. The client identifier as described in Section 2.2.
redirect_uri redirect_uri
OPTIONAL, as described in Section 3.1.2. OPTIONAL. As described in Section 3.1.2.
scope scope
OPTIONAL. The scope of the access request as described by OPTIONAL. The scope of the access request as described by
Section 3.3. Section 3.3.
state state
RECOMMENDED. An opaque value used by the client to maintain RECOMMENDED. An opaque value used by the client to maintain
state between the request and callback. The authorization state between the request and callback. The authorization
server includes this value when redirecting the user-agent back server includes this value when redirecting the user-agent back
to the client. The parameter SHOULD be used for preventing to the client. The parameter SHOULD be used for preventing
cross-site request forgery as described in Section 10.12. cross-site request forgery as described in Section 10.12.
The client directs the resource owner to the constructed URI using an The client directs the resource owner to the constructed URI using an
HTTP redirection response, or by other means available to it via the HTTP redirection response, or by other means available to it via the
user-agent. user-agent.
skipping to change at page 29, line 17 skipping to change at page 31, line 6
state between the request and callback. The authorization state between the request and callback. The authorization
server includes this value when redirecting the user-agent back server includes this value when redirecting the user-agent back
to the client. The parameter SHOULD be used for preventing to the client. The parameter SHOULD be used for preventing
cross-site request forgery as described in Section 10.12. cross-site request forgery as described in Section 10.12.
The client directs the resource owner to the constructed URI using an The client directs the resource owner to the constructed URI using an
HTTP redirection response, or by other means available to it via the HTTP redirection response, or by other means available to it via the
user-agent. user-agent.
For example, the client directs the user-agent to make the following For example, the client directs the user-agent to make the following
HTTP request using transport-layer security (extra line breaks are HTTP request using TLS (extra line breaks are for display purposes
for display purposes only): only):
GET /authorize?response_type=token&client_id=s6BhdRkqt3&state=xyz GET /authorize?response_type=token&client_id=s6BhdRkqt3&state=xyz
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb HTTP/1.1 &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb HTTP/1.1
Host: server.example.com Host: server.example.com
The authorization server validates the request to ensure all required The authorization server validates the request to ensure all required
parameters are present and valid. The authorization server MUST parameters are present and valid. The authorization server MUST
verify that the redirection URI to which it will redirect the access verify that the redirection URI to which it will redirect the access
token matches a redirection URI registered by the client as described token matches a redirection URI registered by the client as described
in Section 3.1.2. in Section 3.1.2.
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4.2.2. Access Token Response 4.2.2. Access Token Response
If the resource owner grants the access request, the authorization If the resource owner grants the access request, the authorization
server issues an access token and delivers it to the client by adding server issues an access token and delivers it to the client by adding
the following parameters to the fragment component of the redirection the following parameters to the fragment component of the redirection
URI using the "application/x-www-form-urlencoded" format: URI using the "application/x-www-form-urlencoded" format:
access_token access_token
REQUIRED. The access token issued by the authorization server. REQUIRED. The access token issued by the authorization server.
token_type token_type
REQUIRED. The type of the token issued as described in REQUIRED. The type of the token issued as described in
Section 7.1. Value is case insensitive. Section 7.1. Value is case insensitive.
expires_in expires_in
OPTIONAL. The lifetime in seconds of the access token. For RECOMMENDED. The lifetime in seconds of the access token. For
example, the value "3600" denotes that the access token will example, the value "3600" denotes that the access token will
expire in one hour from the time the response was generated. 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 scope
OPTIONAL. The scope of the access token as described by OPTIONAL, if identical to the scope requested by the client,
Section 3.3. otherwise REQUIRED. The scope of the access token as described
by Section 3.3.
state state
REQUIRED if the "state" parameter was present in the client REQUIRED if the "state" parameter was present in the client
authorization request. The exact value received from the authorization request. The exact value received from the
client. client.
The authorization server MUST NOT issue a refresh token. The authorization server MUST NOT issue a refresh token.
For example, the authorization server redirects the user-agent by For example, the authorization server redirects the user-agent by
sending the following HTTP response (URI extra line breaks are for sending the following HTTP response (URI extra line breaks are for
display purposes only): display purposes only):
HTTP/1.1 302 Found HTTP/1.1 302 Found
Location: http://example.com/rd#access_token=2YotnFZFEjr1zCsicMWpAA Location: http://example.com/cb#access_token=2YotnFZFEjr1zCsicMWpAA
&state=xyz&token_type=example&expires_in=3600 &state=xyz&token_type=example&expires_in=3600
Developers should note that some HTTP client implementations do not Developers should note that some user-agents do not support the
support the inclusion of a fragment component in the HTTP "Location" inclusion of a fragment component in the HTTP "Location" response
response header field. Such client will require using other methods header field. Such clients will require using other methods for
for redirecting the client than a 3xx redirection response. For redirecting the client than a 3xx redirection response. For example,
example, returning an HTML page which includes a 'continue' button returning an HTML page which includes a 'continue' button with an
with an action linked to the redirection URI. action linked to the redirection URI.
The client SHOULD ignore unrecognized response parameters. The The client MUST ignore unrecognized response parameters. The access
access token string size is left undefined by this specification. token string size is left undefined by this specification. The
The client should avoid making assumptions about value sizes. The client should avoid making assumptions about value sizes. The
authorization server should document the size of any value it issues. authorization server should document the size of any value it issues.
4.2.2.1. Error Response 4.2.2.1. Error Response
If the request fails due to a missing, invalid, or mismatching If the request fails due to a missing, invalid, or mismatching
redirection URI, or if the client identifier provided is invalid, the redirection URI, or if the client identifier is missing or invalid,
authorization server SHOULD inform the resource owner of the error, the authorization server SHOULD inform the resource owner of the
and MUST NOT automatically redirect the user-agent to the invalid error, and MUST NOT automatically redirect the user-agent to the
redirection URI. invalid redirection URI.
If the resource owner denies the access request or if the request If the resource owner denies the access request or if the request
fails for reasons other than a missing or invalid redirection URI, fails for reasons other than a missing or invalid redirection URI,
the authorization server informs the client by adding the following the authorization server informs the client by adding the following
parameters to the fragment component of the redirection URI using the parameters to the fragment component of the redirection URI using the
"application/x-www-form-urlencoded" format: "application/x-www-form-urlencoded" format:
error error
REQUIRED. A single error code from the following: REQUIRED. A single error code from the following:
invalid_request invalid_request
The request is missing a required parameter, includes an The request is missing a required parameter, includes an
unsupported parameter value, or is otherwise malformed. invalid parameter value, or is otherwise malformed.
unauthorized_client unauthorized_client
The client is not authorized to request an access token The client is not authorized to request an access token
using this method. using this method.
access_denied access_denied
The resource owner or authorization server denied the The resource owner or authorization server denied the
request. request.
unsupported_response_type unsupported_response_type
The authorization server does not support obtaining an The authorization server does not support obtaining an
access token using this method. access token using this method.
invalid_scope invalid_scope
skipping to change at page 31, line 41 skipping to change at page 33, line 35
of the server. of the server.
error_description error_description
OPTIONAL. A human-readable UTF-8 encoded text providing OPTIONAL. A human-readable UTF-8 encoded text providing
additional information, used to assist the client developer in additional information, used to assist the client developer in
understanding the error that occurred. understanding the error that occurred.
error_uri error_uri
OPTIONAL. A URI identifying a human-readable web page with OPTIONAL. A URI identifying a human-readable web page with
information about the error, used to provide the client information about the error, used to provide the client
developer with additional information about the error. developer with additional information about the error.
state state
REQUIRED if a valid "state" parameter was present in the client REQUIRED if a "state" parameter was present in the client
authorization request. The exact value received from the authorization request. The exact value received from the
client. client.
For example, the authorization server redirects the user-agent by For example, the authorization server redirects the user-agent by
sending the following HTTP response: sending the following HTTP response:
HTTP/1.1 302 Found HTTP/1.1 302 Found
Location: https://client.example.com/cb#error=access_denied&state=xyz Location: https://client.example.com/cb#error=access_denied&state=xyz
4.3. Resource Owner Password Credentials 4.3. Resource Owner Password Credentials Grant
The resource owner password credentials grant type is suitable in The resource owner password credentials grant type is suitable in
cases where the resource owner has a trust relationship with the cases where the resource owner has a trust relationship with the
client, such as its device operating system or a highly privileged client, such as the device operating system or a highly privileged
application. The authorization server should take special care when application. The authorization server should take special care when
enabling this grant type, and only allow it when other flows are not enabling this grant type, and only allow it when other flows are not
viable. viable.
The grant type is suitable for clients capable of obtaining the The grant type is suitable for clients capable of obtaining the
resource owner's credentials (username and password, typically using resource owner's credentials (username and password, typically using
an interactive form). It is also used to migrate existing clients an interactive form). It is also used to migrate existing clients
using direct authentication schemes such as HTTP Basic or Digest using direct authentication schemes such as HTTP Basic or Digest
authentication to OAuth by converting the stored credentials to an authentication to OAuth by converting the stored credentials to an
access token. access token.
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The authorization server MUST: The authorization server MUST:
o require client authentication for confidential clients or for any o require client authentication for confidential clients or for any
client that was issued client credentials (or with other client that was issued client credentials (or with other
authentication requirements), authentication requirements),
o authenticate the client if client authentication is included, and o authenticate the client if client authentication is included, and
o validate the resource owner password credentials. o validate the resource owner password credentials.
Since this access token request utilizes the resource owner's Since this access token request utilizes the resource owner's
password, the authorization server MUST protect the endpoint against password, the authorization server MUST protect the endpoint against
brute force attacks. brute force attacks (e.g. using rate-limitation or generating
alerts).
4.3.3. Access Token Response 4.3.3. Access Token Response
If the access token request is valid and authorized, the If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh authorization server issues an access token and optional refresh
token as described in Section 5.1. If the request failed client token as described in Section 5.1. If the request failed client
authentication or is invalid, the authorization server returns an authentication or is invalid, the authorization server returns an
error response as described in Section 5.2. error response as described in Section 5.2.
An example successful response: An example successful response:
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Pragma: no-cache Pragma: no-cache
{ {
"access_token":"2YotnFZFEjr1zCsicMWpAA", "access_token":"2YotnFZFEjr1zCsicMWpAA",
"token_type":"example", "token_type":"example",
"expires_in":3600, "expires_in":3600,
"refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA", "refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA",
"example_parameter":"example_value" "example_parameter":"example_value"
} }
4.4. Client Credentials 4.4. Client Credentials Grant
The client can request an access token using only its client The client can request an access token using only its client
credentials (or other supported means of authentication) when the credentials (or other supported means of authentication) when the
client is requesting access to the protected resources under its client is requesting access to the protected resources under its
control, or those of another resource owner which has been previously control, or those of another resource owner which has been previously
arranged with the authorization server (the method of which is beyond arranged with the authorization server (the method of which is beyond
the scope of this specification). the scope of this specification).
The client credentials grant type MUST only be used by confidential The client credentials grant type MUST only be used by confidential
clients. clients.
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Cache-Control: no-store Cache-Control: no-store
Pragma: no-cache Pragma: no-cache
{ {
"access_token":"2YotnFZFEjr1zCsicMWpAA", "access_token":"2YotnFZFEjr1zCsicMWpAA",
"token_type":"example", "token_type":"example",
"expires_in":3600, "expires_in":3600,
"example_parameter":"example_value" "example_parameter":"example_value"
} }
4.5. Extensions 4.5. Extension Grants
The client uses an extension grant type by specifying the grant type The client uses an extension grant type by specifying the grant type
using an absolute URI (defined by the authorization server) as the 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. adding any additional parameters necessary.
For example, to request an access token using a SAML 2.0 assertion For example, to request an access token using a SAML 2.0 assertion
grant type as defined by [I-D.ietf-oauth-saml2-bearer], the client grant type as defined by [I-D.ietf-oauth-saml2-bearer], the client
makes the following HTTP request using transport-layer security (line makes the following HTTP request using TLS (line breaks are for
breaks are for display purposes only): display purposes only):
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/x-www-form-urlencoded;charset=UTF-8 Content-Type: application/x-www-form-urlencoded;charset=UTF-8
grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Asaml2- grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Asaml2-
bearer&assertion=PEFzc2VydGlvbiBJc3N1ZUluc3RhbnQ9IjIwMTEtMDU bearer&assertion=PEFzc2VydGlvbiBJc3N1ZUluc3RhbnQ9IjIwMTEtMDU
[...omitted for brevity...]aG5TdGF0ZW1lbnQ-PC9Bc3NlcnRpb24- [...omitted for brevity...]aG5TdGF0ZW1lbnQ-PC9Bc3NlcnRpb24-
If the access token request is valid and authorized, the If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh authorization server issues an access token and optional refresh
token as described in Section 5.1. If the request failed client token as described in Section 5.1. If the request failed client
authentication or is invalid, the authorization server returns an authentication or is invalid, the authorization server returns an
error response as described in Section 5.2. error response as described in Section 5.2.
5. Issuing an Access Token 5. Issuing an Access Token
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The authorization server issues an access token and optional refresh The authorization server issues an access token and optional refresh
token, and constructs the response by adding the following parameters token, and constructs the response by adding the following parameters
to the entity body of the HTTP response with a 200 (OK) status code: to the entity body of the HTTP response with a 200 (OK) status code:
access_token access_token
REQUIRED. The access token issued by the authorization server. REQUIRED. The access token issued by the authorization server.
token_type token_type
REQUIRED. The type of the token issued as described in REQUIRED. The type of the token issued as described in
Section 7.1. Value is case insensitive. Section 7.1. Value is case insensitive.
expires_in expires_in
OPTIONAL. The lifetime in seconds of the access token. For RECOMMENDED. The lifetime in seconds of the access token. For
example, the value "3600" denotes that the access token will example, the value "3600" denotes that the access token will
expire in one hour from the time the response was generated. expire in one hour from the time the response was generated.
If omitted, the authorization server SHOULD provide the
expiration time via other means or document the default value.
refresh_token refresh_token
OPTIONAL. The refresh token which can be used to obtain new OPTIONAL. The refresh token which can be used to obtain new
access tokens using the same authorization grant as described access tokens using the same authorization grant as described
in Section 6. in Section 6.
scope scope
OPTIONAL. The scope of the access token as described by OPTIONAL, if identical to the scope requested by the client,
Section 3.3. otherwise REQUIRED. The scope of the access token as described
by Section 3.3.
The parameters are included in the entity body of the HTTP response The parameters are included in the entity body of the HTTP response
using the "application/json" media type as defined by [RFC4627]. The using the "application/json" media type as defined by [RFC4627]. The
parameters are serialized into a JSON structure by adding each parameters are serialized into a JSON structure by adding each
parameter at the highest structure level. Parameter names and string parameter at the highest structure level. Parameter names and string
values are included as JSON strings. Numerical values are included values are included as JSON strings. Numerical values are included
as JSON numbers. The order of parameters does not matter and can as JSON numbers. The order of parameters does not matter and can
vary. vary.
The authorization server MUST include the HTTP "Cache-Control" The authorization server MUST include the HTTP "Cache-Control"
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Pragma: no-cache Pragma: no-cache
{ {
"access_token":"2YotnFZFEjr1zCsicMWpAA", "access_token":"2YotnFZFEjr1zCsicMWpAA",
"token_type":"example", "token_type":"example",
"expires_in":3600, "expires_in":3600,
"refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA", "refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA",
"example_parameter":"example_value" "example_parameter":"example_value"
} }
The client SHOULD ignore unrecognized response parameters. The sizes The client MUST ignore unrecognized value names in the response. The
of tokens and other values received from the authorization server are sizes of tokens and other values received from the authorization
left undefined. The client should avoid making assumptions about server are left undefined. The client should avoid making
value sizes. The authorization server should document the size of assumptions about value sizes. The authorization server should
any value it issues. document the size of any value it issues.
5.2. Error Response 5.2. Error Response
The authorization server responds with an HTTP 400 (Bad Request) The authorization server responds with an HTTP 400 (Bad Request)
status code and includes the following parameters with the response: status code and includes the following parameters with the response:
error error
REQUIRED. A single error code from the following: REQUIRED. A single error code from the following:
invalid_request invalid_request
The request is missing a required parameter, includes an The request is missing a required parameter, includes an
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Client authentication failed (e.g. unknown client, no Client authentication failed (e.g. unknown client, no
client authentication included, or unsupported client authentication included, or unsupported
authentication method). The authorization server MAY authentication method). The authorization server MAY
return an HTTP 401 (Unauthorized) status code to indicate return an HTTP 401 (Unauthorized) status code to indicate
which HTTP authentication schemes are supported. If the which HTTP authentication schemes are supported. If the
client attempted to authenticate via the "Authorization" client attempted to authenticate via the "Authorization"
request header field, the authorization server MUST request header field, the authorization server MUST
respond with an HTTP 401 (Unauthorized) status code, and respond with an HTTP 401 (Unauthorized) status code, and
include the "WWW-Authenticate" response header field include the "WWW-Authenticate" response header field
matching the authentication scheme used by the client. matching the authentication scheme used by the client.
invalid_grant invalid_grant
The provided authorization grant (e.g. authorization The provided authorization grant (e.g. authorization
code, resource owner credentials, client credentials) is code, resource owner credentials) is invalid, expired,
invalid, expired, revoked, does not match the redirection revoked, does not match the redirection URI used in the
URI used in the authorization request, or was issued to authorization request, or was issued to another client.
another client.
unauthorized_client unauthorized_client
The authenticated client is not authorized to use this The authenticated client is not authorized to use this
authorization grant type. authorization grant type.
unsupported_grant_type unsupported_grant_type
The authorization grant type is not supported by the The authorization grant type is not supported by the
authorization server. authorization server.
invalid_scope invalid_scope
The requested scope is invalid, unknown, malformed, or The requested scope is invalid, unknown, malformed, or
exceeds the scope granted by the resource owner. exceeds the scope granted by the resource owner.
error_description error_description
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REQUIRED. The refresh token issued to the client. REQUIRED. The refresh token issued to the client.
scope scope
OPTIONAL. The scope of the access request as described by OPTIONAL. The scope of the access request as described by
Section 3.3. The requested scope MUST NOT include any scope Section 3.3. The requested scope MUST NOT include any scope
not originally granted by the resource owner, and if omitted is not originally granted by the resource owner, and if omitted is
treated as equal to the scope originally granted by the treated as equal to the scope originally granted by the
resource owner. resource owner.
Because refresh tokens are typically long-lasting credentials used to Because refresh tokens are typically long-lasting credentials used to
request additional access tokens, the refresh token is bound to the request additional access tokens, the refresh token is bound to the
client it was issued. If the client type is confidential or the client which it was issued. If the client type is confidential or
client was issued client credentials (or assigned other the client was issued client credentials (or assigned other
authentication requirements), the client MUST authenticate with the authentication requirements), the client MUST authenticate with the
authorization server as described in Section 3.2.1. authorization server as described in Section 3.2.1.
For example, the client makes the following HTTP request using For example, the client makes the following HTTP request using
transport-layer security (extra line breaks are for display purposes transport-layer security (extra line breaks are for display purposes
only): only):
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
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authenticate with the resource server depends on the type of access authenticate with the resource server depends on the type of access
token issued by the authorization server. Typically, it involves token issued by the authorization server. Typically, it involves
using the HTTP "Authorization" request header field [RFC2617] with an using the HTTP "Authorization" request header field [RFC2617] with an
authentication scheme defined by the access token type specification. authentication scheme defined by the access token type specification.
7.1. Access Token Types 7.1. Access Token Types
The access token type provides the client with the information The access token type provides the client with the information
required to successfully utilize the access token to make a protected required to successfully utilize the access token to make a protected
resource request (along with type-specific attributes). The client resource request (along with type-specific attributes). The client
MUST NOT use an access token if it does not understand or does not MUST NOT use an access token if it does not understand the token
trust the token type. type.
For example, the "bearer" token type defined in For example, the "bearer" token type defined in
[I-D.ietf-oauth-v2-bearer] is utilized by simply including the access [I-D.ietf-oauth-v2-bearer] is utilized by simply including the access
token string in the request: token string in the request:
GET /resource/1 HTTP/1.1 GET /resource/1 HTTP/1.1
Host: example.com Host: example.com
Authorization: Bearer 7Fjfp0ZBr1KtDRbnfVdmIw Authorization: Bearer 7Fjfp0ZBr1KtDRbnfVdmIw
while the "mac" token type defined in [I-D.ietf-oauth-v2-http-mac] is while the "mac" token type defined in [I-D.ietf-oauth-v2-http-mac] is
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New response types for use with the authorization endpoint are New response types for use with the authorization endpoint are
defined and registered in the authorization endpoint response type defined and registered in the authorization endpoint response type
registry following the procedure in Section 11.3. Response type registry following the procedure in Section 11.3. Response type
names MUST conform to the response-type ABNF. names MUST conform to the response-type ABNF.
response-type = response-name *( SP response-name ) response-type = response-name *( SP response-name )
response-name = 1*response-char response-name = 1*response-char
response-char = "_" / DIGIT / ALPHA response-char = "_" / DIGIT / ALPHA
If a response type contains one of more space characters (%x20), it 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 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, values does not matter. Only one order of values can be registered,
which covers all other arrangements of the same set of values. which covers all other arrangements of the same set of values.
For example, the response type "token code" is left undefined by this For example, the response type "token code" is left undefined by this
specification. However, an extension can define and register the specification. However, an extension can define and register the
"token code" response type. Once registered, the same combination "token code" response type. Once registered, the same combination
cannot be registered as "code token", but both values can be used to cannot be registered as "code token", but both values can be used to
denote the same response type. denote the same response type.
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Error codes MUST conform to the error-code ABNF, and SHOULD be Error codes MUST conform to the error-code ABNF, and SHOULD be
prefixed by an identifying name when possible. For example, an error prefixed by an identifying name when possible. For example, an error
identifying an invalid value set to the extension parameter "example" identifying an invalid value set to the extension parameter "example"
should be named "example_invalid". should be named "example_invalid".
error-code = ALPHA *error-char error-code = ALPHA *error-char
error-char = "-" / "." / "_" / DIGIT / ALPHA error-char = "-" / "." / "_" / DIGIT / ALPHA
9. Native Applications 9. Native Applications
Native applications are clients installed and executed on the Native applications are clients installed and executed on the device
resource owner's device (i.e. desktop application, native mobile used by the resource owner (i.e. desktop application, native mobile
application). Native applications may require special consideration application). Native applications require special consideration
related to security, platform capabilities, and overall end-user related to security, platform capabilities, and overall end-user
experience. experience.
The authorization endpoint requires interaction between the client The authorization endpoint requires interaction between the client
and the resource owner's user-agent. Native applications can invoke and the resource owner's user-agent. Native applications can invoke
an external user-agent or embed a user-agent within the application. an external user-agent or embed a user-agent within the application.
For example: For example:
o External user-agent - the native application can capture the o External user-agent - the native application can capture the
response from the authorization server using a redirection URI response from the authorization server using a redirection URI
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A malicious client can impersonate another client and obtain access A malicious client can impersonate another client and obtain access
to protected resources, if the impersonated client fails to, or is to protected resources, if the impersonated client fails to, or is
unable to, keep its client credentials confidential. unable to, keep its client credentials confidential.
The authorization server MUST authenticate the client whenever The authorization server MUST authenticate the client whenever
possible. If the authorization server cannot authenticate the client possible. If the authorization server cannot authenticate the client
due to the client's nature, the authorization server MUST require the due to the client's nature, the authorization server MUST require the
registration of any redirection URI used for receiving authorization registration of any redirection URI used for receiving authorization
responses, and SHOULD utilize other means to protect resource owners responses, and SHOULD utilize other means to protect resource owners
from such malicious clients. For example, the authorization server from such potentially malicious clients. For example, the
can engage the resource owner to assist in identifying the client and authorization server can engage the resource owner to assist in
its origin. identifying the client and its origin.
The authorization server SHOULD enforce explicit resource owner The authorization server SHOULD enforce explicit resource owner
authentication and provide the resource owner with information about authentication and provide the resource owner with information about
the client and the requested authorization scope and lifetime. It is the client and the requested authorization scope and lifetime. It is
up to the resource owner to review the information in the context of up to the resource owner to review the information in the context of
the current client, and authorize or deny the request. the current client, and authorize or deny the request.
The authorization server SHOULD NOT process repeated authorization The authorization server SHOULD NOT process repeated authorization
requests automatically (without active resource owner interaction) requests automatically (without active resource owner interaction)
without authenticating the client or relying on other measures to without authenticating the client or relying on other measures to
ensure the repeated request comes from the original client and not an ensure the repeated request comes from the original client and not an
impersonator. impersonator.
10.3. Access Tokens 10.3. Access Tokens
Access token (as well as any access token type-specific attributes) Access token credentials (as well as any confidential access token
MUST be kept confidential in transit and storage, and only shared attributes) MUST be kept confidential in transit and storage, and
among the authorization server, the resource servers the access token only shared among the authorization server, the resource servers the
is valid for, and the client to whom the access token is issued. access token is valid for, and the client to whom the access token is
issued. Access token credentials MUST only be transmitted using TLS
as described in Section 1.6 with server authentication as defined by
[RFC2818].
When using the implicit grant type, the access token is transmitted When using the implicit grant type, the access token is transmitted
in the URI fragment, which can expose it to unauthorized parties. in the URI fragment, which can expose it to unauthorized parties.
The authorization server MUST ensure that access tokens cannot be The authorization server MUST ensure that access tokens cannot be
generated, modified, or guessed to produce valid access tokens by generated, modified, or guessed to produce valid access tokens by
unauthorized parties. unauthorized parties.
The client SHOULD request access tokens with the minimal scope and The client SHOULD request access tokens with the minimal scope and
lifetime necessary. The authorization server SHOULD take the client lifetime necessary. The authorization server SHOULD take the client
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10.4. Refresh Tokens 10.4. Refresh Tokens
Authorization servers MAY issue refresh tokens to web application Authorization servers MAY issue refresh tokens to web application
clients and native application clients. clients and native application clients.
Refresh tokens MUST be kept confidential in transit and storage, and Refresh tokens MUST be kept confidential in transit and storage, and
shared only among the authorization server and the client to whom the shared only among the authorization server and the client to whom the
refresh tokens were issued. The authorization server MUST maintain refresh tokens were issued. The authorization server MUST maintain
the binding between a refresh token and the client to whom it was the binding between a refresh token and the client to whom it was
issued. issued. Refresh tokens MUST only be transmitted using TLS as
described in Section 1.6 with server authentication as defined by
[RFC2818].
The authorization server MUST verify the binding between the refresh The authorization server MUST verify the binding between the refresh
token and client identity whenever the client identity can be token and client identity whenever the client identity can be
authenticated. When client authentication is not possible, the authenticated. When client authentication is not possible, the
authorization server SHOULD deploy other means to detect refresh authorization server SHOULD deploy other means to detect refresh
token abuse. token abuse.
For example, the authorization server could employ refresh token For example, the authorization server could employ refresh token
rotation in which a new refresh token is issued with every access rotation in which a new refresh token is issued with every access
token refresh response. The previous refresh token is invalidated token refresh response. The previous refresh token is invalidated
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token which will inform the authorization server of the breach. token which will inform the authorization server of the breach.
The authorization server MUST ensure that refresh tokens cannot be The authorization server MUST ensure that refresh tokens cannot be
generated, modified, or guessed to produce valid refresh tokens by generated, modified, or guessed to produce valid refresh tokens by
unauthorized parties. unauthorized parties.
10.5. Authorization Codes 10.5. Authorization Codes
The transmission of authorization codes SHOULD be made over a secure The transmission of authorization codes SHOULD be made over a secure
channel, and the client SHOULD implement TLS for use with its channel, and the client SHOULD implement TLS for use with its
redirection URI if the URI identifies a network resource. Effort redirection URI if the URI identifies a network resource. Since
should be made to keep authorization codes confidential. Since
authorization codes are transmitted via user-agent redirections, they authorization codes are transmitted via user-agent redirections, they
could potentially be disclosed through user-agent history and HTTP could potentially be disclosed through user-agent history and HTTP
referrer headers. referrer headers.
Authorization codes operate as plaintext bearer credentials, used to Authorization codes operate as plaintext bearer credentials, used to
verify that the resource owner who granted authorization at the verify that the resource owner who granted authorization at the
authorization server is the same resource owner returning to the authorization server is the same resource owner returning to the
client to complete the process. Therefore, if the client relies on client to complete the process. Therefore, if the client relies on
the authorization code for its own resource owner authentication, the the authorization code for its own resource owner authentication, the
client redirection endpoint MUST require TLS. client redirection endpoint MUST require TLS.
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The authorization server and client SHOULD minimize use of this grant The authorization server and client SHOULD minimize use of this grant
type and utilize other grant types whenever possible. type and utilize other grant types whenever possible.
10.8. Request Confidentiality 10.8. Request Confidentiality
Access tokens, refresh tokens, resource owner passwords, and client Access tokens, refresh tokens, resource owner passwords, and client
credentials MUST NOT be transmitted in the clear. Authorization credentials MUST NOT be transmitted in the clear. Authorization
codes SHOULD NOT be transmitted in the clear. codes SHOULD 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.
10.9. Endpoints Authenticity 10.9. Endpoints Authenticity
In order to prevent man-in-the-middle and phishing attacks, the In order to prevent man-in-the-middle attacks, the authorization
authorization server MUST implement and require TLS with server server MUST implement and require TLS with server authentication as
authentication as defined by [RFC2818] for any request sent to the defined by [RFC2818] for any request sent to the authorization and
authorization and token endpoints. The client MUST validate the token endpoints. The client MUST validate the authorization server's
authorization server's TLS certificate in accordance with its TLS certificate in accordance with its requirements for server
requirements for server identity authentication. identity authentication.
10.10. Credentials Guessing Attacks 10.10. Credentials Guessing Attacks
The authorization server MUST prevent attackers from guessing access The authorization server MUST prevent attackers from guessing access
tokens, authorization codes, refresh tokens, resource owner tokens, authorization codes, refresh tokens, resource owner
passwords, and client credentials. passwords, and client credentials.
When generating tokens and other credentials not intended for Generated tokens and other credentials not intended for handling by
handling by end-users, the authorization server MUST use a reasonable end-users MUST be constructed from a cryptographically strong random
level of entropy in order to mitigate the risk of guessing attacks. or pseudo-random number sequence ([RFC1750]) generated by the
authorization server. The probability of any two values being
identical MUST be less than or equal to 2^(-128) and SHOULD be less
than or equal to 2^(-160).
The authorization server MUST utilize other means to protect The authorization server MUST utilize other means to protect
credentials intended for end-user usage. credentials intended for end-user usage.
10.11. Phishing Attacks 10.11. Phishing Attacks
Wide deployment of this and similar protocols may cause end-users to Wide deployment of this and similar protocols may cause end-users to
become inured to the practice of being redirected to websites where become inured to the practice of being redirected to websites where
they are asked to enter their passwords. If end-users are not they are asked to enter their passwords. If end-users are not
careful to verify the authenticity of these websites before entering careful to verify the authenticity of these websites before entering
their credentials, it will be possible for attackers to exploit this their credentials, it will be possible for attackers to exploit this
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cookie used to authenticate the user-agent). The client SHOULD cookie used to authenticate the user-agent). The client SHOULD
utilize the "state" request parameter to deliver this value to the utilize the "state" request parameter to deliver this value to the
authorization server when making an authorization request. authorization server when making an authorization request.
Once authorization has been obtained from the end-user, the Once authorization has been obtained from the end-user, the
authorization server redirects the end-user's user-agent back to the authorization server redirects the end-user's user-agent back to the
client with the required binding value contained in the "state" client with the required binding value contained in the "state"
parameter. The binding value enables the client to verify the parameter. The binding value enables the client to verify the
validity of the request by matching the binding value to the user- validity of the request by matching the binding value to the user-
agent's authenticated state. The binding value used for CSRF agent's authenticated state. The binding value used for CSRF
protection MUST contain a non-guessable value, and the user-agent's protection MUST contain a non-guessable value (as described in
authenticated state (e.g. session cookie, HTML5 local storage) MUST Section 10.10), and the user-agent's authenticated state (e.g.
be kept in a location accessible only to the client and the user- session cookie, HTML5 local storage) MUST be kept in a location
agent (i.e., protected by same-origin policy). accessible only to the client and the user-agent (i.e., protected by
same-origin policy).
A CSRF attack against the authorization server's authorization A CSRF attack against the authorization server's authorization
endpoint can result in an attacker obtaining end-user authorization endpoint can result in an attacker obtaining end-user authorization
for a malicious client without involving or alerting the end-user. for a malicious client without involving or alerting the end-user.
The authorization server MUST implement CSRF protection for its The authorization server MUST implement CSRF protection for its
authorization endpoint, and ensure that a malicious client cannot authorization endpoint, and ensure that a malicious client cannot
obtain authorization without the awareness and explicit consent of obtain authorization without the awareness and explicit consent of
the resource owner. the resource owner.
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authorization server's authorization endpoint web page in a authorization server's authorization endpoint web page in a
transparent iframe overlaid on top of a set of dummy buttons which transparent iframe overlaid on top of a set of dummy buttons which
are carefully constructed to be placed directly under important are carefully constructed to be placed directly under important
buttons on the authorization page. When an end-user clicks a buttons on the authorization page. When an end-user clicks a
misleading visible button, the end-user is actually clicking an misleading visible button, the end-user is actually clicking an
invisible button on the authorization page (such as an "Authorize" invisible button on the authorization page (such as an "Authorize"
button). This allows an attacker to trick a resource owner into button). This allows an attacker to trick a resource owner into
granting its client access without their knowledge. granting its client access without their knowledge.
To prevent this form of attack, native applications SHOULD use To prevent this form of attack, native applications SHOULD use
external browsers instead of embedding browsers in an iframe when external browsers instead of embedding browsers within the
requesting end-user authorization. For most newer browsers, application when requesting end-user authorization. For most newer
avoidance of iframes can be enforced by the authorization server browsers, avoidance of iframes can be enforced by the authorization
using the (non-standard) "x-frame-options" header. This header can server using the (non-standard) "x-frame-options" header. This
have two values, "deny" and "sameorigin", which will block any header can have two values, "deny" and "sameorigin", which will block
framing, or framing by sites with a different origin, respectively. any framing, or framing by sites with a different origin,
For older browsers, javascript framebusting techniques can be used respectively. For older browsers, javascript framebusting techniques
but may not be effective in all browsers. can be used but may not be effective in all browsers.
10.14. Code Injection and Input Validation 10.14. Code Injection and Input Validation
A code injection attack occurs when an input or otherwise external A code injection attack occurs when an input or otherwise external
variable is used by an application unsanitized and causes variable is used by an application unsanitized and causes
modification to the application logic. This may allow an attacker to modification to the application logic. This may allow an attacker to
gain access to the application device or its data, cause denial of gain access to the application device or its data, cause denial of
service, or a wide range of malicious side-effects. service, or a wide range of malicious side-effects.
The Authorization server and client MUST validate and sanitize any The Authorization server and client MUST validate and sanitize any
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name of the mailing list should be determined in consultation with name of the mailing list should be determined in consultation with
the IESG and IANA. Suggested name: oauth-ext-review. ]] the IESG and IANA. Suggested name: oauth-ext-review. ]]
Within at most 14 days of the request, the Designated Expert(s) will Within at most 14 days of the request, the Designated Expert(s) will
either approve or deny the registration request, communicating this either approve or deny the registration request, communicating this
decision to the review list and IANA. Denials should include an decision to the review list and IANA. Denials should include an
explanation and, if applicable, suggestions as to how to make the explanation and, if applicable, suggestions as to how to make the
request successful. request successful.
Decisions (or lack thereof) made by the Designated Expert(s) can be Decisions (or lack thereof) made by the Designated Expert(s) can be
first appealed to Application Area Directors (contactable using first appealed to Security Area Directors (contactable using
app-ads@tools.ietf.org email address or directly by looking up their app-ads@tools.ietf.org email address or directly by looking up their
email addresses on http://www.iesg.org/ website) and, if the email addresses on http://www.iesg.org/ website) and, if the
appellant is not satisfied with the response, to the full IESG (using appellant is not satisfied with the response, to the full IESG (using
the iesg@iesg.org mailing list). the iesg@iesg.org mailing list).
IANA should only accept registry updates from the Designated IANA should only accept registry updates from the Designated
Expert(s), and should direct all requests for registration to the Expert(s), and should direct all requests for registration to the
review mailing list. review mailing list.
11.1.1. Registration Template 11.1.1. Registration Template
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delegate), with a Specification Required (using terminology from delegate), with a Specification Required (using terminology from
[RFC5226]). However, to allow for the allocation of values prior to [RFC5226]). However, to allow for the allocation of values prior to
publication, the Designated Expert(s) may approve registration once publication, the Designated Expert(s) may approve registration once
they are satisfied that such a specification will be published. they are satisfied that such a specification will be published.
Registration requests should be sent to the [TBD]@ietf.org mailing Registration requests should be sent to the [TBD]@ietf.org mailing
list for review and comment, with an appropriate subject (e.g., list for review and comment, with an appropriate subject (e.g.,
"Request for parameter: example"). [[ Note to RFC-EDITOR: The name of "Request for parameter: example"). [[ Note to RFC-EDITOR: The name of
the mailing list should be determined in consultation with the IESG the mailing list should be determined in consultation with the IESG
and IANA. Suggested name: oauth-ext-review. ]] and IANA. Suggested name: oauth-ext-review. ]]
Within at most 14 days of the request, the Designated Expert(s) will Within at most 14 days of the request, the Designated Expert(s) will
either approve or deny the registration request, communicating this either approve or deny the registration request, communicating this
decision to the review list and IANA. Denials should include an decision to the review list and IANA. Denials should include an
explanation and, if applicable, suggestions as to how to make the explanation and, if applicable, suggestions as to how to make the
request successful. request successful.
Decisions (or lack thereof) made by the Designated Expert(s) can be Decisions (or lack thereof) made by the Designated Expert(s) can be
first appealed to Application Area Directors (contactable using first appealed to Security Area Directors (contactable using
app-ads@tools.ietf.org email address or directly by looking up their app-ads@tools.ietf.org email address or directly by looking up their
email addresses on http://www.iesg.org/ website) and, if the email addresses on http://www.iesg.org/ website) and, if the
appellant is not satisfied with the response, to the full IESG (using appellant is not satisfied with the response, to the full IESG (using
the iesg@iesg.org mailing list). the iesg@iesg.org mailing list).
IANA should only accept registry updates from the Designated IANA should only accept registry updates from the Designated
Expert(s), and should direct all requests for registration to the Expert(s), and should direct all requests for registration to the
review mailing list. review mailing list.
11.2.1. Registration Template 11.2.1. Registration Template
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terminology from [RFC5226]). However, to allow for the allocation of terminology from [RFC5226]). However, to allow for the allocation of
values prior to publication, the Designated Expert(s) may approve values prior to publication, the Designated Expert(s) may approve
registration once they are satisfied that such a specification will registration once they are satisfied that such a specification will
be published. be published.
Registration requests should be sent to the [TBD]@ietf.org mailing Registration requests should be sent to the [TBD]@ietf.org mailing
list for review and comment, with an appropriate subject (e.g., list for review and comment, with an appropriate subject (e.g.,
"Request for response type: example"). [[ Note to RFC-EDITOR: The "Request for response type: example"). [[ Note to RFC-EDITOR: The
name of the mailing list should be determined in consultation with name of the mailing list should be determined in consultation with
the IESG and IANA. Suggested name: oauth-ext-review. ]] the IESG and IANA. Suggested name: oauth-ext-review. ]]
Within at most 14 days of the request, the Designated Expert(s) will Within at most 14 days of the request, the Designated Expert(s) will
either approve or deny the registration request, communicating this either approve or deny the registration request, communicating this
decision to the review list and IANA. Denials should include an decision to the review list and IANA. Denials should include an
explanation and, if applicable, suggestions as to how to make the explanation and, if applicable, suggestions as to how to make the
request successful. request successful.
Decisions (or lack thereof) made by the Designated Expert(s) can be Decisions (or lack thereof) made by the Designated Expert(s) can be
first appealed to Application Area Directors (contactable using first appealed to Security Area Directors (contactable using
app-ads@tools.ietf.org email address or directly by looking up their app-ads@tools.ietf.org email address or directly by looking up their
email addresses on http://www.iesg.org/ website) and, if the email addresses on http://www.iesg.org/ website) and, if the
appellant is not satisfied with the response, to the full IESG (using appellant is not satisfied with the response, to the full IESG (using
the iesg@iesg.org mailing list). the iesg@iesg.org mailing list).
IANA should only accept registry updates from the Designated IANA should only accept registry updates from the Designated
Expert(s), and should direct all requests for registration to the Expert(s), and should direct all requests for registration to the
review mailing list. review mailing list.
11.3.1. Registration Template 11.3.1. Registration Template
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of the mailing list should be determined in consultation with the of the mailing list should be determined in consultation with the
IESG and IANA. Suggested name: oauth-ext-review. ]] IESG and IANA. Suggested name: oauth-ext-review. ]]
Within at most 14 days of the request, the Designated Expert(s) will Within at most 14 days of the request, the Designated Expert(s) will
either approve or deny the registration request, communicating this either approve or deny the registration request, communicating this
decision to the review list and IANA. Denials should include an decision to the review list and IANA. Denials should include an
explanation and, if applicable, suggestions as to how to make the explanation and, if applicable, suggestions as to how to make the
request successful. request successful.
Decisions (or lack thereof) made by the Designated Expert(s) can be Decisions (or lack thereof) made by the Designated Expert(s) can be
first appealed to Application Area Directors (contactable using first appealed to Security Area Directors (contactable using
app-ads@tools.ietf.org email address or directly by looking up their app-ads@tools.ietf.org email address or directly by looking up their
email addresses on http://www.iesg.org/ website) and, if the email addresses on http://www.iesg.org/ website) and, if the
appellant is not satisfied with the response, to the full IESG (using appellant is not satisfied with the response, to the full IESG (using
the iesg@iesg.org mailing list). the iesg@iesg.org mailing list).
IANA should only accept registry updates from the Designated IANA should only accept registry updates from the Designated
Expert(s), and should direct all requests for registration to the Expert(s), and should direct all requests for registration to the
review mailing list. review mailing list.
11.4.1. Registration Template 11.4.1. Registration Template
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12. Acknowledgements 12. Acknowledgements
The initial OAuth 2.0 protocol specification was edited by David The initial OAuth 2.0 protocol specification was edited by David
Recordon, based on two previous publications: the OAuth 1.0 community Recordon, based on two previous publications: the OAuth 1.0 community
specification [RFC5849], and OAuth WRAP (OAuth Web Resource specification [RFC5849], and OAuth WRAP (OAuth Web Resource
Authorization Profiles) [I-D.draft-hardt-oauth-01]. The Security Authorization Profiles) [I-D.draft-hardt-oauth-01]. The Security
Considerations section was drafted by Torsten Lodderstedt, Mark Considerations section was drafted by Torsten Lodderstedt, Mark
McGloin, Phil Hunt, and Anthony Nadalin. McGloin, Phil Hunt, and Anthony Nadalin.
The OAuth 1.0 community specification was edited by Eran Hammer-Lahav The OAuth 1.0 community specification was edited by Eran Hammer and
and authored by Mark Atwood, Dirk Balfanz, Darren Bounds, Richard M. authored by Mark Atwood, Dirk Balfanz, Darren Bounds, Richard M.
Conlan, Blaine Cook, Leah Culver, Breno de Medeiros, Brian Eaton, Conlan, Blaine Cook, Leah Culver, Breno de Medeiros, Brian Eaton,
Kellan Elliott-McCrea, Larry Halff, Eran Hammer-Lahav, Ben Laurie, Kellan Elliott-McCrea, Larry Halff, Eran Hammer, Ben Laurie, Chris
Chris Messina, John Panzer, Sam Quigley, David Recordon, Eran Messina, John Panzer, Sam Quigley, David Recordon, Eran Sandler,
Sandler, Jonathan Sergent, Todd Sieling, Brian Slesinsky, and Andy Jonathan Sergent, Todd Sieling, Brian Slesinsky, and Andy Smith.
Smith.
The OAuth WRAP specification was edited by Dick Hardt and authored by The OAuth WRAP specification was edited by Dick Hardt and authored by
Brian Eaton, Yaron Goland, Dick Hardt, and Allen Tom. Brian Eaton, Yaron Goland, Dick Hardt, and Allen Tom.
This specification is the work of the OAuth Working Group which This specification is the work of the OAuth Working Group which
includes dozens of active and dedicated participants. In particular, includes dozens of active and dedicated participants. In particular,
the following individuals contributed ideas, feedback, and wording the following individuals contributed ideas, feedback, and wording
which shaped and formed the final specification: which shaped and formed the final specification:
Michael Adams, Amanda Anganes, Andrew Arnott, Dirk Balfanz, Aiden Michael Adams, Amanda Anganes, Andrew Arnott, Dirk Balfanz, Aiden
Bell, Scott Cantor, Marcos Caceres, Blaine Cook, Brian Campbell, Bell, Brian Campbell, Scott Cantor, Marcos Caceres, Blaine Cook,
Brian Eaton, Leah Culver, Bill de hOra, Andre DeMarre, Brian Eaton, Roger Crew, Brian Eaton, Leah Culver, Bill de h ra, Andr DeMarre,
Brian Ellin, Igor Faynberg, George Fletcher, Tim Freeman, Evan Brian Eaton, Wolter Eldering, Brian Ellin, Igor Faynberg, George
Gilbert, Yaron Goland, Brent Goldman, Kristoffer Gronowski, Justin Fletcher, Tim Freeman, Evan Gilbert, Yaron Goland, Brent Goldman,
Hart, Dick Hardt, Craig Heath, Phil Hunt, Michael B. Jones, John Kristoffer Gronowski, Justin Hart, Dick Hardt, Craig Heath, Phil
Kemp, Mark Kent, Raffi Krikorian, Chasen Le Hara, Rasmus Lerdorf, Hunt, Michael B. Jones, Terry Jones, John Kemp, Mark Kent, Raffi
Torsten Lodderstedt, Hui-Lan Lu, Casey Lucas, Paul Madsen, Alastair Krikorian, Chasen Le Hara, Rasmus Lerdorf, Torsten Lodderstedt, Hui-
Mair, Eve Maler, James Manger, Mark McGloin, Laurence Miao, Chuck Lan Lu, Casey Lucas, Paul Madsen, Alastair Mair, Eve Maler, James
Mortimore, Anthony Nadalin, Justin Richer, Peter Saint-Andre, Nat Manger, Mark McGloin, Laurence Miao, William Mills, Chuck Mortimore,
Sakimura, Rob Sayre, Marius Scurtescu, Naitik Shah, Luke Shepard, Anthony Nadalin, Julian Reschke, Justin Richer, Peter Saint-Andre,
Vlad Skvortsov, Justin Smith, Niv Steingarten, Christian Stuebner, Nat Sakimura, Rob Sayre, Marius Scurtescu, Naitik Shah, Luke Shepard,
Vlad Skvortsov, Justin Smith, Niv Steingarten, Christian St bner,
Jeremy Suriel, Paul Tarjan, Allen Tom, Franklin Tse, Nick Walker, Jeremy Suriel, Paul Tarjan, Allen Tom, Franklin Tse, Nick Walker,
Shane Weeden, and Skylar Woodward. Shane Weeden, and Skylar Woodward.
This document was produced under the chairmanship of Blaine Cook,
Peter Saint-Andre, Hannes Tschofenig, and Barry Leiba. The area
directors included Lisa Dusseault, Peter Saint-Andre, and Stephen
Farrell.
Appendix A. Editor's Notes Appendix A. Editor's Notes
While many people contributed to this specification throughout its While many people contributed to this specification throughout its
long journey, the editor would like to acknowledge and thank a few long journey, the editor would like to acknowledge and thank a few
individuals for their outstanding and invaluable efforts leading up individuals for their outstanding and invaluable efforts leading up
to the publication of this specification. It is these individuals to the publication of this specification. It is these individuals
without whom this work would not have existed or reached its without whom this work would not have existed or reached its
successful conclusion. successful conclusion.
David Recordon for continuously being one of OAuth's most valuable David Recordon for continuously being one of OAuth s most valuable
assets, bringing pragmatism and urgency to the work, and helping assets, bringing pragmatism and urgency to the work, and helping
shape it from its very beginning, as well as being one of the best shape it from its very beginning, as well as being one of the best
collaborators I had the pleasure of working with. collaborators I had the pleasure of working with.
Mark Nottingham for introducing OAuth to the IETF and setting the
community on this course. Lisa Dusseault for her support and
guidance as the Application area director. Blaine Cook, Peter Saint-
Andre, and Hannes Tschofenig for their work as working group chairs.
James Manger for his creative ideas and always insightful feedback. James Manger for his creative ideas and always insightful feedback.
Brian Campbell, Torsten Lodderstedt, Chuck Mortimore, Justin Richer, Brian Campbell, Torsten Lodderstedt, Chuck Mortimore, Justin Richer,
Marius Scurtescu, and Luke Shepard for their continued participation Marius Scurtescu, and Luke Shepard for their continued participation
and valuable feedback. and valuable feedback.
Special thanks goes to Mike Curtis and Yahoo! for their unconditional Special thanks goes to Mike Curtis and Yahoo! for their unconditional
support of this work for over three years. support of this work for over three years.
13. References 13. References
13.1. Normative References 13.1. Normative References
[RFC1750] Eastlake, D., Crocker, S., and J. Schiller, "Randomness
Recommendations for Security", RFC 1750, December 1994.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999. RFC 2246, January 1999.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
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Cantor, S., Kemp, J., Philpott, R., and E. Maler, Cantor, S., Kemp, J., Philpott, R., and E. Maler,
"Assertions and Protocol for the OASIS Security Assertion "Assertions and Protocol for the OASIS Security Assertion
Markup Language (SAML) V2.0", OASIS Standard saml-core- Markup Language (SAML) V2.0", OASIS Standard saml-core-
2.0-os, March 2005. 2.0-os, March 2005.
[RFC5849] Hammer-Lahav, E., "The OAuth 1.0 Protocol", RFC 5849, [RFC5849] Hammer-Lahav, E., "The OAuth 1.0 Protocol", RFC 5849,
April 2010. April 2010.
Authors' Addresses Authors' Addresses
Eran Hammer-Lahav (editor) Eran Hammer (editor)
Yahoo!
Email: eran@hueniverse.com Email: eran@hueniverse.com
URI: http://hueniverse.com URI: http://hueniverse.com
David Recordon David Recordon
Facebook Facebook
Email: dr@fb.com Email: dr@fb.com
URI: http://www.davidrecordon.com/ URI: http://www.davidrecordon.com/
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