Re: [OAUTH-WG] Nonce-based Replay Protection for DPoP

[Brian Campbell <[e-mail]>]

The discussion during the interim wasn't really about replay protection but
rather about precomputation and exfiltration.  Something like a server
contributed nonce can potentially work to address both though so discussing
such things gets fuzzy quickly.

The approach to reply protection in DPoP is a bit different than what
ACME's done. It's arguably somewhat less robust but I think it is
appreciably simpler and is appropriately so because the replay of a DPoP
proof itself isn't of primary interest. To the extent possible/reasonable,
simplicity was and still is a goal of the DPoP design.



On Tue, Mar 16, 2021 at 5:21 PM Benjamin Kaduk <[e-mail]> wrote:

> On Tue, Mar 16, 2021 at 05:45:46PM -0400, Rifaat Shekh-Yusef wrote:
> > Brian,
> >
> > For a nonce-based replay protection you. might want to look at the ACME
> > protocol here:
> > https://tools.ietf.org/html/rfc8555#section-6.5
>
> Yes, that one is really solid for the sort of thing it does, and I find
> myself recommending it over and over again.
> Of course, that workflow is not universally applicable, so sometimes it's
> not the right thing to do (and I don't remember enough about DPoP to say if
> it works there).
>
> -Ben
>

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