Re: [MLS] Deniability as external to the MLS protocol

Benjamin Beurdouche <benjamin.beurdouche@inria.fr> Fri, 13 November 2020 15:41 UTC

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From: Benjamin Beurdouche <benjamin.beurdouche@inria.fr>
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Date: Fri, 13 Nov 2020 16:41:00 +0100
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Cc: =?utf-8?Q?Sof=C3=ADa_Celi?= <cherenkov@riseup.net>, mls@ietf.org
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To: Raphael Robert <raphael=40wire.com@dmarc.ietf.org>
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Subject: Re: [MLS] Deniability as external to the MLS protocol
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I am supportive of that change as well.
B.

> On Nov 13, 2020, at 4:27 PM, Raphael Robert <raphael=40wire.com@dmarc.ietf.org> wrote:
> 
> Thanks Sofia!
> 
> I think this is exactly what we need to achieve optional deniability for message authorship without touching the authentication guarantees of the the core protocol.
> 
> Raphael
> 
>> On 13 Nov 2020, at 16:01, Sofía Celi <cherenkov@riseup.net> wrote:
>> 
>> Dear all,
>> 
>> As you know, we had many discussions on deniability and solving this
>> problem is not an easy task, as evidence of this thread. To make sure we
>> can work on this optional feature in the future, without modifying the
>> core protocol, we believe that there are no changes needed to be added
>> to the core protocol. Some minor relaxing of the phrasing in the
>> document might be useful, though, and might help for future features as
>> well, so I have submitted PR #437
>> (https://github.com/mlswg/mls-protocol/pull/437). This rephrasing should
>> allow deniability of application messages by allowing the usage of
>> deniable signature keys. Please, let us know of any comments regarding it.
>> 
>> Thank you,
>> 
>> 
>> -- 
>> Sofía Celi
>> @claucece
>> http://claucece.github.io/
>> Cryptographic research and implementation at many places, but mainly at
>> Cloudflare
>> FAB9 3EDC 7CDD 1198 DCFD  4558 91BB 6B45 6F44 2D02
>> 
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