Re: [OAUTH-WG] Microsoft feedback on DPoP during April 2020 IIW session

Benjamin Kaduk <kaduk@mit.edu> Tue, 05 May 2020 22:52 UTC

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Date: Tue, 5 May 2020 15:52:29 -0700
From: Benjamin Kaduk <kaduk@mit.edu>
To: Mike Jones <Michael.Jones=40microsoft.com@dmarc.ietf.org>
Cc: "oauth@ietf.org" <oauth@ietf.org>, Dmitri Zagidulin <dzagidulin@gmail.com>
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Subject: Re: [OAUTH-WG] Microsoft feedback on DPoP during April 2020 IIW session
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On Fri, May 01, 2020 at 02:29:02AM +0000, Mike Jones wrote:
>   *   Is the DPoP signature really needed when requesting a bound token?  It seems like the worst that could happen would be to create a token bound to a key you don't control, which you couldn't use.  Daniel expressed concern about this enabling substitution attacks.

Substitution and confused deputy attacks, yes.  I would feel a lot better
if the signature is required when requesting the bound token; a fair bit of
extra analysis would be needed to try to remove it.

-Ben