JSON Web Token (JWT) Embedded Tokens

JSON Web Token (JWT) Embedded Tokens
Internet-Draft
JWT Embedded Tokens
December 2023
Shekh-Yusef, et al.
Expires 26 June 2024
[Page]
Workgroup:
OAuth Working Group
Internet-Draft:
draft-yusef-oauth-nested-jwt-08
Published:
24 December 2023
Intended Status:
Standards Track
Expires:
26 June 2024
Authors:
R. Shekh-Yusef
Ernst & Young
D. Hardt
Hellō
G. De Marco
Dipartimento per la trasformazione digitale
JSON Web Token (JWT) Embedded Tokens
Abstract
This specification defines a mechanism for embedding tokens into a JWT token.
The JWT token and the embedded tokens are issued by one ore more issuers.
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
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 26 June 2024.
Copyright Notice
Copyright (c) 2023 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
) 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 Revised BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Revised BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s)
controlling the copyright in such materials, this document may not
be modified outside the IETF Standards Process, and derivative
works of it may not be created outside the IETF Standards Process,
except to format it for publication as an RFC or to translate it
into languages other than English.
Table of Contents
1.
Introduction
JWT is a mechanism that is used to transfer claims between two parties across security domains.
There are a number of use cases that need to embed tokens into another JWT token.
This specification defines a mechanism for embedding tokens into a JWT token.
The JWT token and the embedded tokens are issued by different issuers.
Such a mechanism allows for a proper auditing trail that allows the Resource Server to identify who
accessed what resource and on behalf of whom. In some cases, this allows the service consuming
such a token to present some of the information contained in the nested token or claims to the
end user in real-time. In addition, in some cases, this allows the Resource Server to apply
authorization policies based on who requested the access to the resource and on behalf of whom
is the request.
1.1.
Terminology
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
RFC8174
2.
Use Cases
The following are few use cases that might benefit from such a concept:
2.1.
STIR
RFC8225
defines a PASSporT, which is a JWT, that is used to verify
the identity of a caller in an incoming call.
The PASSporT Extension for Diverted Calls draft
STIR
uses a nested
PASSporT to deliver the details of an incoming call that get
redirected. An authentication service acting for a retargeting
entity generates new PASSporT and embeds the original PASSporT inside
the new one. When the new target receives the nested PASSporT it
will be able to validate the enclosing PASSporT and use the details
of the enclosed PASSporT to identify the original target.
In this case, the original JWT is issued by the calling service, and the new enclosing
JWT is issued by the retargeting service.
2.2.
Network Service Mesh (NSM)
Network Service Mesh [NSM] is a mechanism that maps the concept of a
service mesh in Kubernetes to L2/L3 payloads.
NSM GRPS messages may pass through multiple intermediaries, each of
which may transform the message. Each intermediary is expected to
create its own JWT token, and include a claim that contains the JWT it
received with the message it has transformed.
In this case, the original JWT is issued by the entity sending the initial message,
and the new enclosing JWT is issued by the intermediate entity.
2.3.
Multiple Issuers for same Subject
A JWT may have embedded claims from one or more separate Issuers.
An ID Token may have identity claims from independent issuers such as DOB and a professional accreditation.
2.4.
Multiple tokens for multiple resources
A JWT may embeds tokens for different audiences and scopes.
An Authorization Server issues a JWT Token that contains multiple tokens.
Each token has a specialized set of attributes and values.
The tokens can be used by the client to consume protected resources or to obtain access tokens through
a token exchange mechanism, over different domains, releasing the minimum possible number
of information, related on the main subject, necessary for the operation.
3.
Embedded Tokens Request and Response
This section describes the mechanism to request an existing token or tokens to be embedded in a new token. The mechanism
defines a new grant type embedded-tokens for this purpose.
In some cases, the embedding of tokens into a new token could be done locally, if that entity is trusted to so.
If this is the case, then this request/response process defined below is not needed, and the trusted entity can then issue
the tokens in the format specified in section 4; see the examples provided in sections 3.2.1 or 3.2.2.
3.1.
Embedded Tokens Request
When a client receives a token, and it needs to transform or/and enhance the permissions of the token,
the client will send a token request to the AS, and include the received token or tokens to be embedded in the newly
issued token that contains the transformed token details or permissions.
The Client requests a token by sending an authorization request to the authorization server’s token endpoint and include
the following parameters in a JSON payload:
grant_type (REQUIRED)
Carries the new grant type to indicate to the token endpoint that the provided token(s) to be embedded
into the newly issued token. The parameter value MUST be urn:ietf:params:oauth:grant-type:embedded-tokens
tokens (REQUIRED)
An array of objects, where each object represents a token that contains the “type” claim and either the “token” claim,
or the “digest" and “jti” claims, as defined in section 4 of this specification.
The request MAY include any of the following parameters, defined in Section 2.1 of RFC8693: resource, audience, scope,
and requested_token_type.
The following is an example of this new token request:
POST /token
Host: as.example.com
Content-Type: application/json

"grant_type": "urn:ietf:params:oauth:grant-type:embedded-tokens",
"requested_token_type": "urn:ietf:params:oauth:token-type:access_token"
"tokens": [
"type": "urn:ietf:params:oauth:token-type:access_token",
"token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.
eyJzdWIiOiIyMzQ1Njc4OTAxIiwibmFtZSI6IkFsZXggRG9lIiwia
WF0IjoxNTE2MjM5MDIyLCJqdGkiOiJYRkVYYlNDMHhpTXUifQ.
wyycbcY9i0U5YldltNhp4WbM-gF3Q1-jtnc-Wvzyxcg"
The following is the decoded example embedded token in the above example:
"alg": "HS256",
"typ": "JWT"
"sub": "2345678901",
"name": "Alex Doe",
"iat": 1516239022,
"jti": "XFEXbSC0xiMu"
3.2.
Embedded Tokens Successful Response
Before issuing the requested token, the authorization server MUST ensure that the request is
valid and that the embedded token(s) provided in the subject_token is coming from a trusted and approved entity
In the case that the authorization server validated and approved the request, the authorization server
responds to the above request with the standard token exchange response, as defined in section
2.2.1 of [RFC8693].
The type of token issued is as specified in the requested_token_type parameter, if provided.
Otherwise, the type of token issued is at the discretion of the authorization server.
3.2.1.
Embedded Tokens By Value
The authorization server will typically embed the provided tokens directly into the newly issued token,
when there are no concerns around the size of the new token with the embedded tokens.
The following is an example for a JWT token with an embedded token:
"alg": "HS256",
"typ": "JWT",
"sub": "1234567890",
"name": "John Doe",
"iat": 1516239022,
"tokens": [
"type": "urn:ietf:params:oauth:token-type:access_token",
"token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.
eyJzdWIiOiIyMzQ1Njc4OTAxIiwibmFtZSI6IkFsZXggRG9lIiwia
WF0IjoxNTE2MjM5MDIyLCJqdGkiOiJYRkVYYlNDMHhpTXUifQ.
wyycbcY9i0U5YldltNhp4WbM-gF3Q1-jtnc-Wvzyxcg"
3.2.2.
Embedded Tokens By Reference
In some cases, embedding the tokens into the JWT directly might cause the token size to become too large.
In this case, instead of embedding the tokens, the AS will embed a hash of the token(s) and its associated 'jti' claim(s).
This allows the Client to send these tokens directly to the RS with the newly issued JWT, to allow the RS to validate that the
tokens are indeed associated with this new issued JWT.
The following is an example for a JWT token with a reference to the token:
"alg": "HS256",
"typ": "JWT",
"sub": "1234567890",
"name": "John Doe",
"iat": 1516239022,
"tokens": [
"type": "urn:ietf:params:oauth:token-type:access_token:reference",
"digest":
"alg": "sha-256",
"hash": "68e439fd95964da902a8654d47c51d6bc0a7791ea9895173989b263374a9a125"
"jti": "XFEXbSC0xiMu"
3.3.
Embedded Tokens Error Response
If the authorization fails to validate the embedded token, then the authorization server MUST
construct an error response, as specified in section 5.2 of RFC6749. The value of the error
parameter MUST be invalid_embedded_token error code.
The authorization server MAY include additional information regarding the reasons for the error using
the error_description as discussed in Section 5.2 of [RFC6749].
4.
JSON Web Token Claims
This section defines the new claims that will be used to represent the embedded tokens.
It defines one top-level claim, "tokens" claim, and 3 sub claims under that, 'type', "token",
and "digest" claims.
4.1.
"tokens" Claim
The "tokens" claim is an array of objects, where each object represents a token, that contains
the “type” claim and either the “token” claim, or the “digest" and “jti” claims.
4.1.1.
"type" Claim
The "type" claim is used to indicate the type of embedded token, which takes one of the values defined in Section 3, RFC8693.
4.1.2.
"token" Claim
The "token" claim is used to hold the details of the embedded token.
4.1.3.
"digest" Claim
The "digest" claim is an object that is used to hold the hash of the token, to be used to reference the
token instead of embedding it directly in the new JWT.ß
The object contains the following two claims:
4.1.3.1.
"alg" Claim
Holds the algorithm used to hash the token. By default this is "sha-256".
4.1.3.2.
"hash" Claim
Holds the hash value of the token using the algorithm defined in the "alg" claim.
5.
Security Considerations
The entity handling the incoming authorization request MUST validate the token and
ensure that it is coming from a trusted entity, before attempting to embed that into a newly issued JWT.
6.
IANA Considerations
TODO
7.
Acknowledgments
TODO
8.
References
8.1.
Normative References
[RFC7519]
Jones, M.
Bradley, J.
, and
N. Sakimura
"JSON Web Token (JWT)"
RFC 7519
DOI 10.17487/RFC7519
May 2015
[RFC8174]
Leiba, B.
"Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"
BCP 14
RFC 8174
DOI 10.17487/RFC8174
May 2017
8.2.
Informative References
[RFC8225]
Wendt, C.
and
J. Peterson
"PASSporT: Personal Assertion Token"
RFC 8225
DOI 10.17487/RFC8225
February 2018
[RFC8693]
Jones, M.
Nadalin, A.
Campbell, B.
Bradley, J.
, and
C. Mortimore
"OAuth 2.0 Token Exchange"
October 2018
[STIR]
Peterson, J.
"PASSporT Extension for Diverted Calls"
October 2018
Authors' Addresses
Rifaat Shekh-Yusef
Ernst & Young
Ottawa, Ontario, Canada
Email:
rifaat.s.ietf@gmail.com
Dick Hardt
Hellō
Seattle, Washington, USA
Email:
dick.hardt@gmail.com
Giuseppe De Marco
Dipartimento per la trasformazione digitale
Italy
Email:
giuseppe.demarco@teamdigitale.governo.it