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RFC 7523
OAuth Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track B. Campbell
Expires: June 30, 2013 Ping Identity
C. Mortimore
Salesforce
December 27, 2012
JSON Web Token (JWT) Bearer Token Profiles for OAuth 2.0
draft-ietf-oauth-jwt-bearer-04
Abstract
This specification defines the use of a JSON Web Token (JWT) Bearer
Token as a means for requesting an OAuth 2.0 access token as well as
for use as a means of client authentication.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 30, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. HTTP Parameter Bindings for Transporting Assertions . . . . . 4
2.1. Using JWTs as Authorization Grants . . . . . . . . . . . . 4
2.2. Using JWTs for Client Authentication . . . . . . . . . . . 5
3. JWT Format and Processing Requirements . . . . . . . . . . . . 5
3.1. Authorization Grant Processing . . . . . . . . . . . . . . 7
3.2. Client Authentication Processing . . . . . . . . . . . . . 7
4. Authorization Grant Example . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6.1. Sub-Namespace Registration of
urn:ietf:params:oauth:grant-type:jwt-bearer . . . . . . . 8
6.2. Sub-Namespace Registration of
urn:ietf:params:oauth:client-assertion-type:jwt-bearer . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . . 10
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 10
Appendix B. Document History . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
JSON Web Token (JWT) [JWT] is a JavaScript Object Notation (JSON)
[RFC4627] based security token encoding that enables identity and
security information to be shared across security domains. A
security token is generally issued by an identity provider and
consumed by a relying party that relies on its content to identify
the token's subject for security related purposes.
The OAuth 2.0 Authorization Framework [RFC6749] provides a method for
making authenticated HTTP requests to a resource using an access
token. Access tokens are issued to third-party clients by an
authorization server (AS) with the (sometimes implicit) approval of
the resource owner. In OAuth, an authorization grant is an abstract
term used to describe intermediate credentials that represent the
resource owner authorization. An authorization grant is used by the
client to obtain an access token. Several authorization grant types
are defined to support a wide range of client types and user
experiences. OAuth also allows for the definition of new extension
grant types to support additional clients or to provide a bridge
between OAuth and other trust frameworks. Finally, OAuth allows the
definition of additional authentication mechanisms to be used by
clients when interacting with the authorization server.
The Assertion Framework for OAuth 2.0 [I-D.ietf-oauth-assertions] is
an abstract extension to OAuth 2.0 that provides a general framework
for the use of Assertions (a.k.a. Security Tokens) as client
credentials and/or authorization grants with OAuth 2.0. This
specification profiles the Assertion Framework for OAuth 2.0
[I-D.ietf-oauth-assertions] to define an extension grant type that
uses a JSON Web Token (JWT) Bearer Token to request an OAuth 2.0
access token as well as for use as client credentials. The format
and processing rules for the JWT defined in this specification are
intentionally similar, though not identical, to those in the closely
related SAML 2.0 Bearer Assertion Profiles for OAuth 2.0
[I-D.ietf-oauth-saml2-bearer].
This document defines how a JSON Web Token (JWT) Bearer Token can be
used to request an access token when a client wishes to utilize an
existing trust relationship, expressed through the semantics of (and
digital signature calculated over) the JWT, without a direct user
approval step at the authorization server. It also defines how a JWT
can be used as a client authentication mechanism. The use of a
security token for client authentication is orthogonal to and
separable from using a security token as an authorization grant.
They can be used either in combination or separately. Client
authentication using a JWT is nothing more than an alternative way
for a client to authenticate to the token endpoint and must be used
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in conjunction with some grant type to form a complete and meaningful
protocol request. JWT authorization grants may be used with or
without client authentication or identification. Whether or not
client authentication is needed in conjunction with a JWT
authorization grant, as well as the supported types of client
authentication, are policy decisions at the discretion of the
authorization server.
The process by which the client obtains the JWT, prior to exchanging
it with the authorization server or using it for client
authentication, is out of scope.
1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Unless otherwise noted, all the protocol parameter names and values
are case sensitive.
1.2. Terminology
All terms are as defined in The OAuth 2.0 Authorization Framework
[RFC6749], Assertion Framework for OAuth 2.0
[I-D.ietf-oauth-assertions], and JSON Web Token (JWT) [JWT].
2. HTTP Parameter Bindings for Transporting Assertions
The Assertion Framework for OAuth 2.0 [I-D.ietf-oauth-assertions]
defines generic HTTP parameters for transporting Assertions (a.k.a.
Security Tokens) during interactions with a token endpoint. This
section defines the values of those parameters for use with JWT
Bearer Tokens.
2.1. Using JWTs as Authorization Grants
To use a JWT Bearer Token as an authorization grant, use the
following parameter values and encodings.
The value of the "grant_type" parameter MUST be
"urn:ietf:params:oauth:grant-type:jwt-bearer".
The value of the "assertion" parameter MUST contain a single JWT.
The following non-normative example demonstrates an Access Token
Request with a JWT as an authorization grant (with extra line breaks
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for display purposes only):
POST /token.oauth2 HTTP/1.1
Host: as.example.com
Content-Type: application/x-www-form-urlencoded
grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Ajwt-bearer
&assertion=eyJhbGciOiJFUzI1NiJ9.
eyJpc3Mi[...omitted for brevity...].
J9l-ZhwP[...omitted for brevity...]
2.2. Using JWTs for Client Authentication
To use a JWT Bearer Token for client authentication, use the
following parameter values and encodings.
The value of the "client_assertion_type" parameter MUST be
"urn:ietf:params:oauth:client-assertion-type:jwt-bearer".
The value of the "client_assertion" parameter MUST contain a single
JWT.
The following non-normative example demonstrates client
authentication using a JWT during the presentation of an
authorization code grant in an Access Token Request (with extra line
breaks for display purposes only):
POST /token.oauth2 HTTP/1.1
Host: as.example.com
Content-Type: application/x-www-form-urlencoded
grant_type=authorization_code&
code=vAZEIHjQTHuGgaSvyW9hO0RpusLzkvTOww3trZBxZpo&
client_assertion_type=urn%3Aietf%3Aparams%3Aoauth%3A
client-assertion-type%3Ajwt-bearer&
client_assertion=eyJhbGciOiJSUzI1NiJ9.
eyJpc3Mi[...omitted for brevity...].
cC4hiUPo[...omitted for brevity...]
3. JWT Format and Processing Requirements
In order to issue an access token response as described in The OAuth
2.0 Authorization Framework [RFC6749] or to rely on a JWT for client
authentication, the authorization server MUST validate the JWT
according to the criteria below. Application of additional
restrictions and policy are at the discretion of the authorization
server.
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o The JWT MUST contain an "iss" (issuer) claim that contains a
unique identifier for the entity that issued the JWT.
o The JWT MUST contain a "sub" (subject) claim identifying the
subject of the transaction. The subject MAY identify the resource
owner for whom the access token is being requested. For client
authentication, the subject MUST be the "client_id" of the OAuth
client. When using a JWT as an authorization grant, the subject
SHOULD identify an authorized accessor for whom the access token
is being requested (typically the resource owner, or an authorized
delegate).
o The JWT MUST contain an "aud" (audience) claim containing an
audience value that identifies the authorization server, or the
service provider principal entity of its controlling domain, as an
intended audience. The token endpoint URL of the authorization
server MAY be used as an acceptable value for an "aud" element.
The authorization server MUST verify that it is an intended
audience for the JWT.
o The JWT MUST contain an "exp" (expiration) claim that limits the
time window during which the JWT can be used. The authorization
server MUST verify that the expiration time has not passed,
subject to allowable clock skew between systems. The
authorization server MAY reject JWTs with an "exp" claim value
that is unreasonably far in the future.
o The JWT MAY contain an "nbf" (not before) claim that identifies
the time before which the token MUST NOT be accepted for
processing.
o The JWT MAY contain an "iat" (issued at) claim that identifies the
time at which the JWT was issued. The authorization server MAY
reject JWTs with an "iat" claim value that is unreasonably far in
the past.
o The JWT MAY contain a "jti" (JWT ID) claim that provides a unique
identifier for the token. The authorization server MAY ensure
that JWTs are not replayed by maintaining the set of used "jti"
values for the length of time for which the JWT would be
considered valid based on the applicable "exp" instant.
o The JWT MAY contain other claims.
o The JWT MUST be digitally signed by the issuer and the
authorization server MUST verify the signature.
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o The authorization server MUST verify that the JWT is valid in all
other respects per JSON Web Token (JWT) [JWT].
3.1. Authorization Grant Processing
If present, the authorization server MUST also validate the client
credentials.
If the JWT is not valid, or the current time is not within the
token's valid time window for use, the authorization server MUST
construct an error response as defined in OAuth 2.0 [RFC6749]. The
value of the "error" parameter MUST be the "invalid_grant" error
code. The authorization server MAY include additional information
regarding the reasons the JWT was considered invalid using the
"error_description" or "error_uri" parameters.
For example:
HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store
{
"error":"invalid_grant",
"error_description":"Audience validation failed"
}
3.2. Client Authentication Processing
If the client JWT is not valid, or its subject confirmation
requirements cannot be met, the authorization server MUST construct
an error response as defined in OAuth 2.0 [RFC6749]. The value of
the "error" parameter MUST be the "invalid_client" error code. The
authorization server MAY include additional information regarding the
reasons the JWT was considered invalid using the "error_description"
or "error_uri" parameters.
4. Authorization Grant Example
Though non-normative, the following examples illustrate what a
conforming JWT and access token request would look like.
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Below is an example JSON object that could be encoded to produce the
JWT Claims Object for a JWT:
{"iss":"https://jwt-idp.example.com",
"sub":"mailto:mike@example.com",
"aud":"https://jwt-rp.example.net",
"nbf":1300815780,
"exp":1300819380,
"http://claims.example.com/member":true}
The following example JSON object, used as the header of a JWT,
declares that the JWT is signed with the ECDSA P-256 SHA-256
algorithm.
{"alg":"ES256"}
To present the JWT with the claims and header shown in the previous
example as part of an access token request, for example, the client
might make the following HTTPS request (with extra line breaks for
display purposes only):
POST /token.oauth2 HTTP/1.1
Host: authz.example.net
Content-Type: application/x-www-form-urlencoded
grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Ajwt-bearer
&assertion=eyJhbGciOiJFUzI1NiJ9.
eyJpc3Mi[...omitted for brevity...].
J9l-ZhwP[...omitted for brevity...]
5. Security Considerations
No additional security considerations apply beyond those described
within The OAuth 2.0 Authorization Framework [RFC6749], the Assertion
Framework for OAuth 2.0 [I-D.ietf-oauth-assertions], and the JSON Web
Token (JWT) [JWT] specification.
6. IANA Considerations
6.1. Sub-Namespace Registration of
urn:ietf:params:oauth:grant-type:jwt-bearer
This specification registers the value "grant-type:jwt-bearer" in the
IANA urn:ietf:params:oauth registry established in An IETF URN Sub-
Namespace for OAuth [RFC6755].
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o URN: urn:ietf:params:oauth:grant-type:jwt-bearer
o Common Name: JWT Bearer Token Grant Type Profile for OAuth 2.0
o Change controller: IETF
o Specification Document: [[this document]]
6.2. Sub-Namespace Registration of
urn:ietf:params:oauth:client-assertion-type:jwt-bearer
This specification registers the value
"client-assertion-type:jwt-bearer" in the IANA urn:ietf:params:oauth
registry established in An IETF URN Sub-Namespace for OAuth
[RFC6755].
o URN: urn:ietf:params:oauth:client-assertion-type:jwt-bearer
o Common Name: JWT Bearer Token Profile for OAuth 2.0 Client
Authentication
o Change controller: IETF
o Specification Document: [[this document]]
7. References
7.1. Normative References
[I-D.ietf-oauth-assertions]
Campbell, B., Mortimore, C., Jones, M., and Y. Goland,
"Assertion Framework for OAuth 2.0",
draft-ietf-oauth-assertions-08 (work in progress),
November 2012.
[JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", draft-ietf-oauth-json-web-token (work in
progress), December 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework",
RFC 6749, October 2012.
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[RFC6755] Campbell, B. and H. Tschofenig, "An IETF URN Sub-Namespace
for OAuth", RFC 6755, October 2012.
7.2. Informative References
[I-D.ietf-oauth-saml2-bearer]
Campbell, B. and C. Mortimore, "SAML 2.0 Bearer Assertion
Profiles for OAuth 2.0", draft-ietf-oauth-saml2-bearer-15
(work in progress), November 2012.
Appendix A. Acknowledgements
This profile was derived from SAML 2.0 Bearer Assertion Profiles for
OAuth 2.0 [I-D.ietf-oauth-saml2-bearer] by Brian Campbell and Chuck
Mortimore.
Appendix B. Document History
[[ to be removed by the RFC editor before publication as an RFC ]]
-04
o Changed the name of the "prn" claim to "sub" (subject) both to
more closely align with SAML name usage and to use a more
intuitive name.
o Added seriesInfo information to Internet Draft references.
-03
o Reference RFC 6749 and RFC 6755.
-02
o Add more text to intro explaining that an assertion/JWT grant type
can be used with or without client authentication/identification
and that client assertion/JWT authentication is nothing more than
an alternative way for a client to authenticate to the token
endpoint
o Add examples to Sections 2.1 and 2.2
o Update references
-01
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o Tracked specification name changes: "The OAuth 2.0 Authorization
Protocol" to "The OAuth 2.0 Authorization Framework" and "OAuth
2.0 Assertion Profile" to "Assertion Framework for OAuth 2.0".
o Merged in changes between draft-ietf-oauth-saml2-bearer-11 and
draft-ietf-oauth-saml2-bearer-13. All changes were strictly
editorial.
-00
o Created the initial IETF draft based upon
draft-jones-oauth-jwt-bearer-04 with no normative changes.
Authors' Addresses
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: http://self-issued.info/
Brian Campbell
Ping Identity Corp.
Email: brian.d.campbell@gmail.com
Chuck Mortimore
Salesforce
Email: cmortimore@salesforce.com
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