Open Authentication Protocol T. Lodderstedt, Ed.
Internet-Draft YES.com AG
Intended status: Standards Track V. Dzhuvinov
Expires: November 29, 2018 Connect2id Ltd.
May 28, 2018
JWT Response for OAuth Token Introspection
draft-lodderstedt-oauth-jwt-introspection-response-01
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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provisions of BCP 78 and BCP 79.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requesting a JWT Response . . . . . . . . . . . . . . . . . . 2
3. JWT Response . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Client Metadata . . . . . . . . . . . . . . . . . . . . . . . 4
5. Authorization Server Metadata . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7.1. OAuth Dynamic Client Registration Metadata Registration . 5
7.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 5
7.2. OAuth Authorization Server Metadata Registration . . . . 6
7.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 6
7.3. OAuth Token Introspection Response . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8.1. Cross-JWT Confusion . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Document History . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
OAuth 2.0 Token Introspection [RFC7662] specifies a method for a
protected resource to query an OAuth 2.0 authorization server to
determine the state of an access token and obtain data associated
with the access token. This allows deployments to implement
identifier-based access tokens in an interoperable way.
The introspection response as specified in OAuth 2.0 Token
Introspection [RFC7662] is a plain JSON object. However, there are
use cases where the resource server requires stronger assurance that
the authorisation server issued the access token, including cases
where the authorisation server assumes liability for the token's
content. 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 the
introspection response. This specification extends the Token
Introspection endpoint with the capability to return responses as
JWTs.
2. Requesting a JWT Response
A resource server requests to receive a JWT introspection response by
including an Accept header with content type "application/jwt" in the
introspection request.
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The following is a non-normative example request:
POST /introspect HTTP/1.1
Host: server.example.com
Accept: application/jwt
Content-Type: application/x-www-form-urlencoded
token=2YotnFZFEjr1zCsicMWpAA
3. JWT Response
The introspection endpoint responds with a JWT, setting the Content-
Type header to "application/jwt".
This JWT MUST contain the claims "iss" and "aud" in order to prevent
misuse of the JWT as ID or access token (see Section 8.1).
This JWT may furthermore contain all other claims described 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:
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{
"sub": "Z5O3upPC88QrAjx00dis",
"aud": "https://protected.example.net/resource",
"scope": "read write dolphin",
"iss": "https://server.example.com/",
"active": true,
"exp": 1419356238,
"iat": 1419350238,
"client_id": "l238j323ds-23ij4",
"given_name": "John",
"family_name":"Doe",
"birthdate":"1982-02-01"
}
4. Client Metadata
The authorization server determines what algorithm to employ to
secure the JWT for a particular introspection response. This
decision can be based on registered metadata parameters for the
resource server, supplied via dynamic client registration with the
resource server posing as the client.
The parameter names follow the pattern established by OpenID Connect
Dynamic Client Registration [OpenID.Registration] for configuring
signing and encryption algorithms for JWT responses at the UserInfo
endpoint.
The following client metadata parameters are introduced by this
specification:
introspection_signed_response_alg JWS [RFC7515] "alg" algorithm JWA
[RFC7518] REQUIRED for signing introspection responses. If
this is specified, the response will be JWT [RFC7519]
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_encrypted_response_alg JWE [RFC7516] "alg" algorithm
JWA [RFC7518] 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 [RFC7519]. The default, if
omitted, is that no encryption is performed.
introspection_encrypted_response_enc JWE [RFC7516] "enc" algorithm
JWA [RFC7518] REQUIRED for encrypting introspection
responses. If "introspection_encrypted_response_alg" is
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specified, the default for this value is A128CBC-HS256. When
"introspection_encrypted_response_enc" is included,
"introspection_encrypted_response_alg" MUST also be provided.
Resource servers may register their public encryption keys using the
"jwks_uri" or "jwks" metadata parameters.
5. Authorization Server Metadata
Authorization servers SHOULD publish the supported algorithms for
signing and encrypting the JWT of an introspection response by
utilizing OAuth Authorization Server Metadata parameters.
The following parameters are introduced by this specification:
introspection_signing_alg_values_supported OPTIONAL. JSON array
containing a list of the JWS [RFC7515] signing algorithms
("alg" values) JWA [RFC7518] supported by the Introspection
Endpoint to sign the response.
introspection_encryption_alg_values_supported OPTIONAL. JSON array
containing a list of the JWE [RFC7516] encryption algorithms
("alg" values) JWA [RFC7518] supported by the Introspection
Endpoint to encrypt the response.
introspection_encryption_enc_values_supported OPTIONAL. JSON array
containing a list of the JWE [RFC7516] encryption algorithms
("enc" values) JWA [RFC7518] supported by the Introspection
Endpoint to encrypt the response.
6. Acknowledgements
We would like to thank Petteri Stenius and Neil Madden for their
valuable feedback.
7. IANA Considerations
7.1. OAuth Dynamic Client Registration Metadata Registration
This specification requests registration of the following client
metadata definitions in the IANA "OAuth Dynamic Client Registration
Metadata" registry [IANA.OAuth.Parameters] established by [RFC7591]:
7.1.1. Registry Contents
o Client Metadata Name: "introspection_signed_response_alg"
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o Client Metadata Description: String value indicating the client's
desired introspection response signing algorithm.
o Change Controller: IESG
o Specification Document(s): Section 4 of [[ this specification ]]
o Client Metadata Name: "introspection_encrypted_response_alg"
o Client Metadata Description: String value specifying the desired
introspection response encryption algorithm (alg value).
o Change Controller: IESG
o Specification Document(s): Section 4 of [[ this specification ]]
o Client Metadata Name: "introspection_encrypted_response_enc"
o Client Metadata Description: String value specifying the desired
introspection response encryption algorithm (enc value).
o Change Controller: IESG
o Specification Document(s): Section 4 of [[ this specification ]]
7.2. OAuth Authorization Server Metadata Registration
This specification requests registration of the following value in
the IANA "OAuth Authorization Server Metadata" registry
[IANA.OAuth.Parameters] established by [I-D.ietf-oauth-discovery].
7.2.1. Registry Contents
o Metadata Name: "introspection_signing_alg_values_supported"
o Metadata Description: JSON array containing a list of algorithms
supported by the authorization server for introspection response
signing.
o Change Controller: IESG
o Specification Document(s): Section 5 of [[ this specification ]]
o Metadata Name: "introspection_encryption_alg_values_supported"
o Metadata Description: JSON array containing a list of algorithms
supported by the authorization server for introspection response
encryption (alg value).
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o Change Controller: IESG
o Specification Document(s): Section 5 of [[ this specification ]]
o Metadata Name: "introspection_encryption_enc_values_supported"
o Metadata Description: JSON array containing a list of algorithms
supported by the authorization server for introspection response
encryption (enc value).
o Change Controller: IESG
o Specification Document(s): Section 5 of [[ this specification ]]
7.3. OAuth Token Introspection Response
TBD: add all OpenID Connect standard claims.
8. Security Considerations
8.1. Cross-JWT Confusion
JWT introspection responses and OpenID Connect ID Tokens are
syntactically more or less equivalent. An attacker could therefore
try to misuse an JWT obtained from an introspection response to
impersonate the user whose claims are included in this JWT at a
OpenID Connect RP. Such an attack is treated and prevented like any
other token substitution attack. The AS MUST include the claims
"iss" and "aud" into every JWT introspection response. This allows
every well behaving OpenID Connect RP to detect substitution by
checking the "iss" and "aud" claims as described in Section 3.1.3.7.
of [OpenID.Core]. RPs should also use and check the "nonce"
parameter and claim to prevent token and code replay.
Resource servers utilizing JWTs to represent structured access tokens
could be susceptible to replay attacks as well. Resource servers
should therefore apply proper counter measures against replay as
described in [I-D.ietf-oauth-security-topics], section 2.2.
JWT Confusion and other attacks on JWTs are discussed in detail in
[I-D.ietf-oauth-jwt-bcp].
9. References
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9.1. Normative References
[I-D.ietf-oauth-discovery]
Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
Authorization Server Metadata", draft-ietf-oauth-
discovery-10 (work in progress), March 2018.
[I-D.ietf-oauth-jwt-bcp]
Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
Current Practices", draft-ietf-oauth-jwt-bcp-03 (work in
progress), May 2018.
[I-D.ietf-oauth-security-topics]
Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett,
"OAuth 2.0 Security Best Current Practice", draft-ietf-
oauth-security-topics-06 (work in progress), May 2018.
[OpenID.Core]
NRI, Ping Identity, Microsoft, Google, and Salesforce,
"OpenID Connect Core 1.0 incorporating errata set 1", Nov
2014,
<http://openid.net/specs/openid-connect-core-1_0.html>.
[OpenID.Registration]
NRI, Ping Identity, and Microsoft, "OpenID Connect Dynamic
Client Registration 1.0 incorporating errata set 1", Nov
2014, <https://openid.net/specs/
openid-connect-registration-1_0.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, DOI 10.17487/RFC2246, January 1999,
<https://www.rfc-editor.org/info/rfc2246>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
RFC 7516, DOI 10.17487/RFC7516, May 2015,
<https://www.rfc-editor.org/info/rfc7516>.
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[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/info/rfc7518>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>.
[RFC7591] Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and
P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
RFC 7591, DOI 10.17487/RFC7591, July 2015,
<https://www.rfc-editor.org/info/rfc7591>.
[RFC7662] Richer, J., Ed., "OAuth 2.0 Token Introspection",
RFC 7662, DOI 10.17487/RFC7662, October 2015,
<https://www.rfc-editor.org/info/rfc7662>.
9.2. Informative References
[IANA.OAuth.Parameters]
IANA, "OAuth Parameters",
<http://www.iana.org/assignments/oauth-parameters>.
Appendix A. Document History
[[ To be removed from the final specification ]]
-01
o fixed typos in client meta data field names
o added OAuth Server Metadata parameters to publish algorithms
supported for signing and encrypting the introspection response
o added registration of new parameters for OAuth Server Metadata and
Client Registration
o added explicit request for JWT introspection response
o made iss and aud claims mandatory in introspection response
o Stylistic and clarifying edits, updates references
-00
o initial version
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Authors' Addresses
Torsten Lodderstedt (editor)
YES.com AG
Email: torsten@lodderstedt.net
Vladimir Dzhuvinov
Connect2id Ltd.
Email: vladimir@connect2id.com
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