[OAUTH-WG] Followup on draft-ietf-oauth-token-exchange-12.txt

Eric Rescorla <ekr@rtfm.com> Sat, 14 April 2018 00:39 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Fri, 13 Apr 2018 17:38:33 -0700
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Subject: [OAUTH-WG] Followup on draft-ietf-oauth-token-exchange-12.txt
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Hi folks,

I've gone over draft-ietf-oauth-token-exchange-12 and things seem
generally OK. I do still have one remaining concern, which is about
the actor claim. Specifically, what is the RP supposed to do when they
encounter it? This seems kind of underspecified.

In particular:

1. What facts am I supposed to know here? Merely that everyone in
   the chain signed off on the next person in the chain acting as them?

2. Am I just supposed to pretend that the person presenting the token
   is the identity at the top of the chain? Say I have the
   delegation A -> B -> C, and there is some resource which
   B can access but A and C cannot, should I give access?

I think the first question definitely needs an answer. The second
question I guess we could make not answer, but it's pretty hard
to know how to make a system with this left open.

-Ekr