Re: [OAUTH-WG] I-D Action: draft-ietf-oauth-access-token-jwt-03.txt

[Vittorio Bertocci <[e-mail]>]

Dear all,
I finally found the time to push a new draft of the JWT profile for ATs.
This version incorporates the feedback kindly provided by Brian and Aaron
at IETF105.
Unfortunately I didn't have a chance to participate to IETF106, hence we
didn't do much progress since then.
There are still two areas we didn't manage to reach consensus on:

1. Mechanisms for signaling whether the AT was obtained by a user or an
application

This point was the subject of intense debate on the list leading to IETF105.
One insight that emerged from the IETF105 discussion was that the use case
here is more about whether the AT has been obtained via a grant that
authenticated the client (regardless of what specific grant was used) vs a
public client grant- that information can be relevant to a resource as it
determines whether the identity of the client can be used in authorization
decisions (in the former case) or not (in the public client case). If
that's the scenario we are truly after, a simple, possibly optional boolean
claim (say AuthenticatedClient) would suffice.
Note for the people who didn't read the spec: I removed any reference to
this already in draft-ietf-oauth-access-token-jwt-01. I think this is an
important and useful info and standardizing it would be beneficial for
middleware and SDK creators, but ultimately this is an interop profile
hence if there's no strong desire to reach an agreement here, I am also OK
with dropping the matter and not address this function in the spec.
To summarize, I have two questions here:

A. Do we believe it's worth it to formalize in the profile a mechanism to
indicate whether the client th obtained the AT authenticated itself with
the AS?
B. If yes, are you OK wiht an optional bool claim here?


2. Claims indicating session properties

This is one area where I am far more passionate about, as it represents a
fundamental aspect that production systems (and in particular 1st party
solutions) already rely on in the current proprietary JTW ATs.
The profile currently includes the claims auth_time, acr and amr -
capturing the values of those properties at the time of the latest
authentication the user performed in the session used to issue the current
AT: at session creation, at auth step up time and so on.
Those are values that API need in order to make authorization decisions; in
the case of 1st party APIs, the AT is the only artifact they ever receive
hence there is no other way for an API to determine whether the caller
performed say MFA in order to obtain the current AT.
Since the first draft, some people signaled concerns about the current
mechanisms thru which those claims get their value. For example, it has
been proposed to maintain the original values of auth_time, acr & amr and
introduce additional claims to indicate changes (like stepup).
I am not clear on what cold go wrong with the current approach, hence I
don't have an immediate grasp of how changes like the above would help.
If the people uncomfortable with the current proposal could detail their
concern, we can brainstorm ways to make that info available to API in a
safer way. To summarize:

A. Do you have concerns with the current auth_time, arm, acr proposal? Can
you spell them out? (please read the relevant parts of the spec before
chiming in :))
B. If yes, what can we do to make that info available to RSs in a way that
makes you comfortable?



Thanks

V.

On Mon, Dec 16, 2019 at 2:49 PM <[e-mail]> wrote:

>
> A New Internet-Draft is available from the on-line Internet-Drafts
> directories.
> This draft is a work item of the Web Authorization Protocol WG of the IETF.
>
>         Title           : JSON Web Token (JWT) Profile for OAuth 2.0
> Access Tokens
>         Author          : Vittorio Bertocci
>         Filename        : draft-ietf-oauth-access-token-jwt-03.txt
>         Pages           : 16
>         Date            : 2019-12-16
>
> Abstract:
>    This specification defines a profile for issuing OAuth 2.0 access
>    tokens in JSON web token (JWT) format.  Authorization servers and
>    resource servers from different vendors can leverage this profile to
>    issue and consume access tokens in interoperable manner.
>
>
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-ietf-oauth-access-token-jwt/
>
> There are also htmlized versions available at:
> https://tools.ietf.org/html/draft-ietf-oauth-access-token-jwt-03
> https://datatracker.ietf.org/doc/html/draft-ietf-oauth-access-token-jwt-03
>
> A diff from the previous version is available at:
> https://www.ietf.org/rfcdiff?url2=draft-ietf-oauth-access-token-jwt-03
>
>
> Please note that it may take a couple of minutes from the time of
> submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>
> _______________________________________________
> OAuth mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/oauth
>