Hi Karl,
My comments below.

Thank you for your patience with my suggestions and questions,
Atul

On Mon, Nov 3, 2025 at 7:51 PM Karl McGuinness <[email protected]>
wrote:

> A couple of other points to add
>
>    - The ID-JAG has the same `iss`+`sub` as the SSO ID Token for the
>    Resource Authorization Server as RP.
>
> I'm not sure the ID-JAG is required to have the same `iss` or the same
`sub` as the ID-Token. Perhaps the resource authorization server uses a
separate identifier format and value for users than the IdP, and the ID-JAG
Authorization Server (which in my proposal is separate from the IdP) does
that mapping before it issues the ID-JAG. The resource authorization server
can be configured to trust the ID-JAG Authorization Server instead of the
IdP for the ID-JAG.


>
>    - This ensures the same account linking/resolution logic for SSO can
>    be reused for ID-JAG processing reducing surface area and security issues
>    of generic claims mappings needed for something like vanilla JWT
>    Authorization Grant in a federation.   For example, the Resource
>    Authorization Server as RP stores the IdP's iss+sub during JIT from SSO
>    then matches the `iss`+`sub in the ID-JAG.
>
> It's an architectural question for organizations about how the IdP issued
identifiers should be mapped to the identifiers that the application
recognizes. So if we are able to propose a standard that doesn't preclude
the possibility that there may be a separate authorization server, then it
makes the standard more valuable.

I think there is sufficient evidence that many large organizations choose
to have separation between the authenticating party and the authorizing
party, so as a standards body, we should permit and encourage both
possibilities.


>    - The Resource Authorization Server can trust multiple IdPs and
>    therefore multiple ID-JAG issuers (assuming the secure account resolution
>    of multiple federation identifiers)
>
> I'm not sure if it matters whether the party that a resource authorization
server trusts for an ID-JAG is a combined "ID Token Issuer + Authorization
Server", or just an "Authorization Server". Am I missing something?


> -Karl
>
> On Mon, Nov 3, 2025 at 7:00 PM <[email protected]> wrote:
>
>> I think the issue is that the id_token “audience” restrictions require
>> them to be the same. Otherwise the “IdP Authorization Server” (that didn’t
>> issue the id_token) would need to reject the id_token when received because
>> the “audience” wouldn’t match. I’m not crazy about the idea that says a
>> bunch of different services performing different tasks are still all the
>> same “audience”.
>>
>> George Fletcher
>> Identity Standards Architect
>> Practical Identity LLC
>>
>>
>>
>> On Nov 3, 2025, at 5:30 PM, Atul Tulshibagwale <atul=
>> [email protected]> wrote:
>>
>> Hi Jeff,
>> I'm not thinking of changing anything in the draft (e.g. using
>> Transaction Tokens, WITs etc.)
>> I'm only suggesting that we should not assume that the IdP that issued
>> the ID-Token is the same as the "IdP Authorization Server" that issues the
>> ID-JAG.
>>
>> Atul
>>
>>
>> On Mon, Nov 3, 2025 at 1:29 PM Lombardo, Jeff <jeffsec=
>> [email protected]> wrote:
>>
>>> Not going against anything Aaron said, is your question @Atul
>>> Tulshibagwale <[email protected]> cause you are thinking
>>> ahead of:
>>>
>>> 1/ A transaction Token could be exchanged for a ID-JAG?
>>> 2/ A Workload Identity Token could be exchanged for an ID-JAG?
>>>
>>>
>>>
>>> Jeff
>>>
>>>
>>>
>>> *Jean-François “Jeff” Lombardo* | Amazon Web Services
>>>
>>>
>>>
>>> Architecte Principal de Solutions, Spécialiste de Sécurité
>>> Principal Solution Architect, Security Specialist
>>> Montréal, Canada
>>>
>>> *Commentaires à propos de notre échange? **Exprimez-vous **ici*
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>>>
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>>>
>>>
>>>
>>> *From:* Aaron Parecki <[email protected]>
>>> *Sent:* November 3, 2025 4:17 PM
>>> *To:* Atul Tulshibagwale <[email protected]>
>>> *Cc:* oauth <[email protected]>
>>> *Subject:* [EXT] [OAUTH-WG] Re: Separating the ID-JAG issuer from the
>>> ID-Token issuer
>>>
>>>
>>>
>>> *CAUTION*: This email originated from outside of the organization. Do
>>> not click links or open attachments unless you can confirm the sender and
>>> know the content is safe.
>>>
>>>
>>>
>>> *AVERTISSEMENT*: Ce courrier électronique provient d’un expéditeur
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>>>
>>>
>>> For some background, the reason for this draft and the ID-JAG in the
>>> first place is to enable an Authorization Server to issue its own access
>>> tokens in response to a cross-domain artifact. This is better than the
>>> other two alternatives which would be:
>>>
>>>
>>>
>>> 1. Client sends the IdP-issued ID Token to the Authorization Server in
>>> the other domain (violates ID Token "audience" policy processing)
>>>
>>> 2. Have the IdP issue an access token that the Resource Server in
>>> the other domain accepts (no protocol violation, but experience has shown
>>> Resource Server implementers do not want this)
>>>
>>>
>>>
>>> Now to your actual question, why not enable the ID-JAG issuer to be
>>> separate from the ID Token issuer. This would also violate the ID Token
>>> "audience" processing, since the ID Token would be presented to an entity
>>> different from the issuer of the ID Token.
>>>
>>>
>>>
>>> On Mon, Nov 3, 2025 at 3:49 PM Atul Tulshibagwale <atul=
>>> [email protected]> wrote:
>>>
>>> Hi all,
>>>
>>> Great to see the "Identity Assertion JWT Authorization Grant
>>> <https://datatracker.ietf.org/doc/draft-ietf-oauth-identity-assertion-authz-grant/>"
>>> proposal being accepted by OAuth. I'd like to propose that we should not
>>> assume that the issuer of the ID-Token is the same as the issuer of the
>>> ID-JAG. There doesn't seem to be any reason provided for this either in the
>>> draft or in the short discussion we had today.
>>>
>>>
>>>
>>> It's just something that is assumed in the draft, and I feel that can be
>>> generalized without affecting anything in the draft.
>>>
>>>
>>>
>>> To address Aaron's response that "if you want them separate, then you
>>> return to the ID-Chaining draft": I feel there's a lot of value in this
>>> (ID-JAG) specification, and being able to apply to more use cases broadens
>>> the value of this specification.
>>>
>>>
>>>
>>> I'd love to know what could be potential issues if the ID-JAG issuer is
>>> not assumed to be the same as the ID-Token issuer.
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Atul
>>>
>>>
>>>
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