JWT Response for OAuth Token Introspection
draft-lodderstedt-oauth-jwt-introspection-response-00

Abstract

This draft proposes an additional JSON Web Token (JWT) based response for OAuth 2.0 Token Introspection.

Status of This Memo

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This Internet-Draft will expire on September 16, 2018.

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Table of Contents

• 1. Introduction
• 2. JWT Response
• 3. Client Metadata
• 4. Acknowledgements
• 5. IANA Considerations
• 6. Security Considerations
• 7. Normative References
• Authors' Addresses

1. Introduction

OAuth 2.0 Token Introspection specifies a method for a protected resource to query an OAuth 2.0 authorization server to determine the active state and meta-information of an OAuth 2.0 token. This allows deployments to implement identifier-based access tokens in an interoperable way.

The introspection endpoint as specified in OAuth 2.0 Token Introspection is a plain JSON object in "application/json" format. However, there are use cases where the resource server needs evidence about the fact the AS issued the access token and is liable for its contents. An example is a resource server using verified person data to create qualified electronic signatures.

In such use cases, it would be useful to return a signed JWT as introspection response. This draft extends the Token Introspection endpoint by the capability to return responses as JWTs.

2. JWT Response

The introspection endpoint may respond with a JWT in "application/jwt" format.

This JWT may contain all the members describes in Section 2.2. of [RFC7662].

The following is a non-normative example response (with line breaks for display purposes only):

HTTP/1.1 200 OK
Content-Type: application/jwt

eyJraWQiOiIxIiwiYWxnIjoiUlMyNTYifQ.eyJzdWIiOiJaNU8zdXBQQzg4UXJBa
ngwMGRpcyIsImF1ZCI6Imh0dHBzOlwvXC9wcm90ZWN0ZWQuZXhhbXBsZS5uZXRcL
3Jlc291cmNlIiwiZXh0ZW5zaW9uX2ZpZWxkIjoidHdlbnR5LXNldmVuIiwic2Nvc
GUiOiJyZWFkIHdyaXRlIGRvbHBoaW4iLCJpc3MiOiJodHRwczpcL1wvc2VydmVyL
mV4YW1wbGUuY29tXC8iLCJhY3RpdmUiOnRydWUsImV4cCI6MTQxOTM1NjIzOCwia
WF0IjoxNDE5MzUwMjM4LCJjbGllbnRfaWQiOiJsMjM4ajMyM2RzLTIzaWo0Iiwid
XNlcm5hbWUiOiJqZG9lIn0.HEQHf05vqVvWVnWuEjbzUnPz6JDQVR69QkxgzBNq5
kk-sK54ieg1STazXGsdFAT8nUhiiV1f_Z4HOKNnBs8TLKaFXokhA0MqNBOYI--2u
nVHDqI_RPmC3p0NmP02Xmv4hzxFmTmpgjSy3vpKQDihOjhwNBh7G81JNaJqjJQTR
v_1dHUPJotQjMK3k8_5FyiO2p64Y2VyxyQn1VWVlgOHlJwhj6BaGHk4Qf5F8DHQZ
1WCPg2p_-hwfINfXh1_buSjxyDRF4oe9pKy6ZB3ejh9qIMm-WrwltuU1uWMXxN6e
S6tUtpKo8UCHBwLWCHmJN7KU6ZojmaISspdS23lELAlyw

The example response contains the following JSON document:

{
  "sub": "Z5O3upPC88QrAjx00dis",
  "aud": "https://protected.example.net/resource",
  "extension_field": "twenty-seven",
  "scope": "read write dolphin",
  "iss": "https://server.example.com/",
  "active": true,
  "exp": 1419356238,
  "iat": 1419350238,
  "client_id": "l238j323ds-23ij4",
  "username": "jdoe"
}

3. Client Metadata

The authorization server determines what format to use for a particular introspection response. The decision can be based on the mechanisms described in this section.

The proposal is to register resource servers as clients and let them determine the response format by utilizing new parameters for dynamic client registration.

The new parameters follow the pattern established by the OpenID Connect Dynamic Client registration specification for configuring signing and encryption algorithms for the user info endpoint.

The following parameters are introduced by this specification:

introspection_response_signed_response_alg

JWS alg algorithm JWA REQUIRED for signing introspection responses. If this is specified, the response will be JWT serialized, and signed using JWS. The default, if omitted, is for the introspection response to return the Claims as a UTF-8 encoded JSON object using the application/json content-type as defined in [RFC7662].

introspection_response_encrypted_response_alg

JWE alg algorithm JWA REQUIRED for encrypting introspection responses. If both signing and encryption are requested, the response will be signed then encrypted, with the result being a Nested JWT, as defined in JWT. The default, if omitted, is that no encryption is performed.

introspection_response_encrypted_response_enc

JWE enc algorithm JWA REQUIRED for encrypting introspection responses. If introspection_response_encrypted_response_algy is specified, the default for this value is A128CBC-HS256. When introspection_response_encrypted_response_enc is included, introspection_response_encrypted_response_alg MUST also be provided.

Resource servers may register their public encryption keys using the jwks_uri or jwks metadata parameters.

4. Acknowledgements

We would like to thank ...

5. IANA Considerations

TBD

6. Security Considerations

TBD

7. Normative References

Authors' Addresses