Re: [OAUTH-WG] draft-bertocci-oauth-access-token-jwt-00

[Brian Campbell <[e-mail]>]

+1 to David's question here. I'd like to see justifying use cases (beyond
just the fact that some people are already doing it) for auth_time, acr,
and amr to be available in OAuth JWT access tokens. Those claims are
defined for, and in the context of, an ID Token and I fear that codifying
their use in an access token will lead to misuse and/or confusion.

On Mon, Apr 1, 2019 at 1:03 PM David Waite <[e-mail]>
wrote:

> Do we know if there is a justifying use case for auth_time, acr, and amr
> to be available in OAuth JWT access tokens? These are meant to be messages
> about the client, either directly (in the case of client credentials) or
> about its delegated authorization of the user.
>
> Embedding attributes about the user (such as group membership and roles)
> can be used for the resource to make finer-grained decisions than scopes,
> but normally I would expect say acr limitations enforced by a resource to
> instead be controlled by the AS requiring a higher quality authentication
> to release certain scopes.
>
> Thats of course not to say extensions to OAuth such as OIDC can’t provide
> these values, just that they might better be defined by those extensions.
>
> -DW
>
> On Apr 1, 2019, at 9:12 AM, George Fletcher <
> gffletch=[e-mail]> wrote:
>
> Thanks for writing this up. One comment on auth_time...
>
>    auth_time  OPTIONAL - as defined in section 2 of [OpenID.Core <https://tools.ietf.org/html/draft-bertocci-oauth-access-token-jwt-00#ref-OpenID.Core>].
>       Important: as this claim represents the time at which the end user
>       authenticated, its value will remain the same for all the JWT
>       access tokens issued within that session.  For example: all the
>       JWT access tokens obtained with a given refresh token will all
>       have the same value of auth_time, corresponding to the instant in
>       which the user first authenticated to obtain the refresh token.
>
>
> During a current session a user can be challenged for additional
> credentials or required to re-authenticate due to a number of different
> reasons. For example, OIDC prompt=login or max_age=NNN. In this context,
> I'd assume that the auth_time value should be updated to the latest time at
> which the user authenticated.
>
> If we need a timestamp for when the "session" started, then there could be
> a session_start_time claim.
>
> Thanks,
> George
>
> On 3/24/19 7:29 PM, Vittorio Bertocci wrote:
>
> Dear all,
> I just submitted a draft describing a JWT profile for OAuth 2.0 access
> tokens. You can find it in
> https://datatracker.ietf.org/doc/draft-bertocci-oauth-access-token-jwt/.
> I have a slot to discuss this tomorrow at IETF 104 (I'll be presenting
> remotely). I look forward for your comments!
>
> Here's just a bit of backstory, in case you are interested in how this doc
> came to be. The trajectory it followed is somewhat unusual.
>
>    - Despite OAuth2 not requiring any specific format for ATs, through
>    the years I have come across multiple proprietary solution using JWT for
>    their access token. The intent and scenarios addressed by those solutions
>    are mostly the same across vendors, but the syntax and interpretations in
>    the implementations are different enough to prevent developers from reusing
>    code and skills when moving from product to product.
>    - I asked several individuals from key products and services to share
>    with me concrete examples of their JWT access tokens (THANK YOU Dominick
>    Baier (IdentityServer), Brian Campbell (PingIdentity), Daniel Dobalian
>    (Microsoft), Karl Guinness (Okta) for the tokens and explanations!).
>    I studied and compared all those instances, identifying commonalities
>    and differences.
>    - I put together a presentation summarizing my findings and suggesting
>    a rough interoperable profile (slides:
>    https://sec.uni-stuttgart.de/_media/events/osw2019/slides/bertocci_-_a_jwt_profile_for_ats.pptx
>    <https://sec..uni-stuttgart.de/_media/events/osw2019/slides/bertocci_-_a_jwt_profile_for_ats.pptx>
>    ) - got early feedback from Filip Skokan on it. Thx Filip!
>    - The presentation was followed up by 1.5 hours of unconference
>    discussion, which was incredibly valuable to get tight-loop feedback and
>    incorporate new ideas. John Bradley, Brian Campbell Vladimir Dzhuvinov,
>    Torsten Lodderstedt, Nat Sakimura, Hannes Tschofenig were all there
>    and contributed generously to the discussion. Thank you!!!
>    Note: if you were at OSW2019, participated in the discussion and
>    didn't get credited in the draft, my apologies: please send me a note and
>    I'll make things right at the next update.
>    - On my flight back I did my best to incorporate all the ideas and
>    feedback in a draft, which will be discussed at IETF104 tomorrow. Rifaat,
>    Hannes and above all Brian were all super helpful in negotiating the
>    mysterious syntax of the RFC format and submission process.
>
> I was blown away by the availability, involvement and willingness to
> invest time to get things right that everyone demonstrated in the process.
> This is an amazing community.
> V.
>
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