draft-ietf-oauth-revocation-01.txt   draft-ietf-oauth-revocation-02.txt 
OAuth Working Group T. Lodderstedt, Ed. OAuth Working Group T. Lodderstedt, Ed.
Internet-Draft Deutsche Telekom AG Internet-Draft Deutsche Telekom AG
Intended status: Standards Track S. Dronia Intended status: Standards Track S. Dronia
Expires: April 9, 2013 Expires: May 22, 2013
M. Scurtescu M. Scurtescu
Google Google
October 6, 2012 November 18, 2012
Token Revocation Token Revocation
draft-ietf-oauth-revocation-01 draft-ietf-oauth-revocation-02
Abstract Abstract
This draft proposes an additional endpoint for OAuth authorization This document proposes an additional endpoint for OAuth authorization
servers for revoking tokens. servers, which allows clients to notify the authorization server that
a previously obtained refresh or access token is no longer needed.
This allows the authorization server to cleanup security credentials.
A revocation request will invalidate the actual token and, if
applicable, other tokens based on the same access grant.
Requirements Language Requirements Language
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
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 9, 2013. This Internet-Draft will expire on May 22, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Token Revocation . . . . . . . . . . . . . . . . . . . . . . . 3 2. Token Revocation . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Cross-Origin Support . . . . . . . . . . . . . . . . . . . 5 2.1. Cross-Origin Support . . . . . . . . . . . . . . . . . . . 5
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . . 6 6.1. Normative References . . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . . 6 6.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
The OAuth 2.0 core specification [I-D.ietf-oauth-v2] defines several The OAuth 2.0 core specification [RFC6749] defines several ways for a
ways for a client to obtain refresh and access tokens. This client to obtain refresh and access tokens. This specification
specification supplements the core specification with a mechanism to supplements the core specification with a mechanism to revoke both
revoke both types of tokens. A token is the external representation types of tokens. A token is the external representation of an access
of an access grant issued by a resource owner to a particular client. grant issued by a resource owner to a particular client. A
A revocation request may discard the actual token as well as other revocation request will invalidate the actual token and, if
tokens based on the same access grant and the access grant itself. applicable, other tokens based on the same access grant and the
access grant itself.
This mechanism facilitates the following use cases:
o The end-user triggers revocation from within the client that sends
the appropriate revocation request to the autorization server.
The request causes the removal of the client's access grant the
particular token refers to. From the end-user's perspective, this
looks like a "logout" or "reset" function. This use case makes it
even more comfortable to the end-user to revoke his access grant
immediately via the client.
o In contrast to revocation by a client, the authorization server
(or a related entity) may offer its end-users a self-care portal
to delete access grants given to clients independent of any token
storing devices. Such a portal offers the possibility to an end-
user to look at and revoke all access grants he once authorized.
In cases the token storing device is not available, e.g. it is
lost or stolen, revocation by a self-care portal is the only
possibility to limit or avoid abuse.
In the end, security, usability, and ease of use are increased by
token revocation.
By using an additional endpoint, the token revocation endpoint, From an end-user's perception, OAuth is often used to log into a
clients can request the revocation of a particular token. Compliant certain site or app. This revocation mechanism allows a client to
implementation MUST support the revocation of refresh tokens, access invalidate its tokens if the end-user logs out, changes identity, or
token revocation MAY be supported. uninstalls the respective app. Notifying the authorization server
that the token is no longer needed allows the authorization server to
cleanup data associated with that token (e.g. session data) and the
underlying access grant. This prevents a situation, where there is
still a valid access grant for that particular client, which the end-
user is not aware of. This way, token revocation prevents abuse of
abandoned tokens and facilitates a better end-user experience since
invalidated access grants will no longer turn up in a list of access
grants the authorization server might present to the end-user.
2. Token Revocation 2. Token Revocation
The client requests the revocation of a particular token by making an The client requests the revocation of a particular token by making an
HTTP POST request to the token revocation endpoint. The location of HTTP POST request to the token revocation endpoint. The location of
the token revocation endpoint can be found in the authorization the token revocation endpoint can be found in the authorization
server's documentation. The token endpoint URI MAY include a query server's documentation. The token endpoint URI MAY include a query
component. component.
Compliant implementation MUST support the revocation of refresh
tokens, access token revocation SHOULD be supported.
Note: Depending on the authorization server's token design,
revocation of access tokens might be a costly process. For example,
revocation of self-contained access tokens requires (time-consuming)
backend calls between resource and authorization server on every
request to the resource server or to push notifications from the
authorization server to the affected resource servers.
Alternatively, authorization servers may choose to issue short living
access tokens, which can be refreshed at any time using the
corresponding refresh tokens. In this case, a client would revoke
the refresh token and access tokens issued based on this particular
refresh token are at most valid until expiration. Whether this is an
viable option or whether access token revocation is required should
be decided based on the service provider's risk analysis.
Since requests to the token revocation endpoint result in the Since requests to the token revocation endpoint result in the
transmission of plain text credentials in the HTTP request, the transmission of plain text credentials in the HTTP request, the
authorization server MUST require the use of a transport-layer authorization server MUST require the use of a transport-layer
security mechanism when sending requests to the token revocation security mechanism when sending requests to the token revocation
endpoints. The authorization server MUST support TLS 1.0 endpoints. The authorization server MUST support TLS 1.0
([RFC2246]), SHOULD support TLS 1.2 ([RFC5246]) and its future ([RFC2246]), SHOULD support TLS 1.2 ([RFC5246]) and its future
replacements, and MAY support additional transport-layer mechanisms replacements, and MAY support additional transport-layer mechanisms
meeting its security requirements. meeting its security requirements.
The client constructs the request by including the following The client constructs the request by including the following
parameters using the "application/x-www-form-urlencoded" format in parameters using the "application/x-www-form-urlencoded" format in
the HTTP request entity-body: the HTTP request entity-body:
token REQUIRED. The token that the client wants to get revoked. token REQUIRED. The token that the client wants to get revoked.
Note: the authorization server is supposed to detect the Note: the authorization server is supposed to detect the
token type automatically. token type automatically.
The client also includes its authentication credentials as described The client also includes its authentication credentials as described
in Section 2.3. of [I-D.ietf-oauth-v2]. in Section 2.3. of [RFC6749].
For example, a client may request the revocation of a refresh token For example, a client may request the revocation of a refresh token
with the following request (line breaks are for display purposes with the following request (line breaks are for display purposes
only): only):
POST /revoke HTTP/1.1 POST /revoke HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/x-www-form-urlencoded Content-Type: application/x-www-form-urlencoded
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
token=45ghiukldjahdnhzdauz& token=45ghiukldjahdnhzdauz&
The authorization server first validates the client credentials (in The authorization server first validates the client credentials (in
case of a confidential client) and verifies whether the client is case of a confidential client) and verifies whether the client is
authorized to revoke the particular token based on the client authorized to revoke the particular token. It therefore validates
identity and its policy. For example, only the client the token has whether this token had been issued to this client.
been issued for might be allowed to revoke it. It is also
conceivable to allow a dedicated user self-care portal to revoke all
kinds of tokens.
In the next step, the authorization server invalidates the token and In the next step, the authorization server invalidates the token and
the respective access grant. If the particular token is a refresh the respective access grant. If the particular token is a refresh
token and the authorization server supports the revocation of access token and the authorization server supports the revocation of access
tokens, then the authorization server SHOULD also invalidate all tokens, then the authorization server SHOULD also invalidate all
access tokens based on the same access grant. access tokens based on the same access grant.
Whether the revocation takes effect instantly or with some delay Note: for considerations regarding access token revocation see note
depends on the architecture of the particular deployment. The client above.
MUST NOT make any assumptions about the timing and MUST NOT use the
token again. The client MUST NOT use the token again after revocation.
The authorization server indicates a successful processing of the The authorization server indicates a successful processing of the
request by a HTTP status code 200. Status code 401 indicates a request by a HTTP status code 200. Status code 401 indicates a
failed client authentication, whereas a status code 403 is used if failed client authentication, whereas a status code 403 is used if
the client is not authorized to revoke the particular token. For all the client is not authorized to revoke the particular token. For all
other error conditions, a status code 400 is used along with an error other error conditions, a status code 400 is used along with an error
response as defined in section 5.2. of [I-D.ietf-oauth-v2]. The response as defined in section 5.2. of [RFC6749]. The following
following error codes are defined for the token revocation endpoint: error codes are defined for the token revocation endpoint:
unsupported_token_type The authorization server does not support the unsupported_token_type The authorization server does not support the
revocation of the presented token type. I.e. the client revocation of the presented token type. I.e. the client
tried to revoke an access token on a server not supporting tried to revoke an access token on a server not supporting
this feature. this feature.
invalid_token The presented token is invalid. invalid_token The presented token is invalid.
2.1. Cross-Origin Support 2.1. Cross-Origin Support
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Error response: Error response:
package.myCallback({"error":"invalid_token"}); package.myCallback({"error":"invalid_token"});
Clients should be aware that when relying on JSONP, a malicious Clients should be aware that when relying on JSONP, a malicious
revokation end-point may attempt to inject malicious code into the revokation end-point may attempt to inject malicious code into the
client. client.
3. Acknowledgements 3. Acknowledgements
We would like to thank Michiel de Jong, Doug Foiles, Paul Madsen, We would like to thank Hannes Tschofenig, Michiel de Jong, Doug
George Fletcher, Sebastian Ebling, Christian Stuebner, Brian Foiles, Paul Madsen, George Fletcher, Sebastian Ebling, Christian
Campbell, Igor Faynberg, Lukas Rosenstock, and Justin P. Richer for Stuebner, Brian Campbell, Igor Faynberg, Lukas Rosenstock, and Justin
their valuable feedback. P. Richer for their valuable feedback.
4. IANA Considerations 4. IANA Considerations
This draft includes no request to IANA. This draft includes no request to IANA.
5. Security Considerations 5. Security Considerations
All relevant security considerations have been given in the If the authorization server does not support access token revocation,
functional specification. access tokens will not be immediately invalidated when the
corresponding refresh token is revoked. Deployments MUST take this
in account when conducting their security risk analysis.
Cleaning up tokens using revocation contributes to overall security
and privacy since it reduces the liklyhood for abuse of abandoned
tokens. This specification in general does not intend to provide
countermeasures against token theft and abuse. For a discussion of
respective threats and countermeasures, consult the security
considerations given in section 10 of the OAuth core specification
[RFC6749] and the OAuth threat model document
[I-D.ietf-oauth-v2-threatmodel].
Malicious clients could attempt to use the new endpoint to launch
denial of service attacks on the authorization server. Appropriate
countermeasures, which must be in place for the token endpoint as
well, should be applied to the revocation endpoint.
A malicious client may attempt to guess valid tokens on this
endpoints. As a pre-requisite, the client either requires a valid
client_id of a public client or the credentials of a confidential
client. An sucessful attempt would result in the revocation of the
respective token, thus causing the legitimate client to loss its
authorization. The malicious client does not gain further
advantages.
6. References 6. References
6.1. Normative References 6.1. Normative References
[I-D.ietf-oauth-v2]
Hardt, D., "The OAuth 2.0 Authorization Framework",
draft-ietf-oauth-v2-31 (work in progress), August 2012.
[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.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework",
RFC 6749, October 2012.
6.2. Informative References 6.2. Informative References
[I-D.ietf-oauth-v2-threatmodel]
Lodderstedt, T., McGloin, M., and P. Hunt, "OAuth 2.0
Threat Model and Security Considerations",
draft-ietf-oauth-v2-threatmodel-08 (work in progress),
October 2012.
[W3C.WD-cors-20120403] [W3C.WD-cors-20120403]
Kesteren, A., "Cross-Origin Resource Sharing", World Wide Kesteren, A., "Cross-Origin Resource Sharing", World Wide
Web Consortium LastCall WD-cors-20120403, April 2012, Web Consortium LastCall WD-cors-20120403, April 2012,
<http://www.w3.org/TR/2012/WD-cors-20120403>. <http://www.w3.org/TR/2012/WD-cors-20120403>.
[jsonp] Ippolito, B., "Remote JSON - JSONP", December 2005. [jsonp] Ippolito, B., "Remote JSON - JSONP", December 2005.
Authors' Addresses Authors' Addresses
Torsten Lodderstedt (editor) Torsten Lodderstedt (editor)
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