Re: [Acme] Signature misuse vulnerability in draft-barnes-acme-04

Phillip Hallam-Baker <phill@hallambaker.com> Thu, 13 August 2015 15:00 UTC

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Date: Thu, 13 Aug 2015 11:00:31 -0400
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From: Phillip Hallam-Baker <phill@hallambaker.com>
To: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
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Cc: Richard Barnes <rlb@ipv.sx>, "acme@ietf.org" <acme@ietf.org>, Andrew Ayer <agwa@andrewayer.name>, Stephen Farrell <stephen.farrell@cs.tcd.ie>
Subject: Re: [Acme] Signature misuse vulnerability in draft-barnes-acme-04
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On Thu, Aug 13, 2015 at 10:51 AM, Ilari Liusvaara <
ilari.liusvaara@elisanet.fi>; wrote:

> On Thu, Aug 13, 2015 at 10:27:09AM -0400, Phillip Hallam-Baker wrote:
> > +1
> >
> > I would much rather block the entire class of attacks rather than spend
> any
> > time working out if there is a way to do this with ECC based keys.
>
> FYI, one of the five proposals for CFRG signatures:
> - One is definitely vulernable (and key-checking won't help).
> - Two are definitely not vulernable.
> - Two I don't know.
>
> So good idea to just block the attack.
>

I hadn't actually thought of using this as a discrimination function on the
CFRG algorithms. It is as good as anything else.