Re: [MLS] Syntax and mechanics for external commit

Raphael Robert <raphael@wire.com> Wed, 14 October 2020 11:15 UTC

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From: Raphael Robert <raphael@wire.com>
In-Reply-To: <c9466359-a43a-c3a8-cd2f-c54eb87948d6@wickr.com>
Date: Wed, 14 Oct 2020 13:15:13 +0200
Cc: Richard Barnes <rlb@ipv.sx>, Brendan McMillion <brendan@cloudflare.com>, Messaging Layer Security WG <mls@ietf.org>
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To: Joel Alwen <jalwen@wickr.com>
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Subject: Re: [MLS] Syntax and mechanics for external commit
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Yes, that’s how you derive who added someone to the group. If Alice creates and Add Proposal to add Bob, the semantic interpretation would be “Alice added Bob”, regardless of who committed in the end.

Obviously this has to do quite a bit with the application logic and some applications might not care at all about it. But we should be clear on what information is conveyed where.

Raphael

> On 14 Oct 2020, at 12:52, Joel Alwen <jalwen@wickr.com> wrote:
> 
> On 14/10/2020 12:43, Raphael Robert wrote:
>> I can definitely think of cases where the explicit Add Proposal is desired,
>> for example when an external party (like a server) issues that Add Proposal.
> 
> OK, I think I get it. To make sure: Is the use case for explicitly including the
> Add proposal in an ext. comm. for the commitor to prove to the group that the
> server (or whoever else made the proposal) OKed the commitor joining the group?
> 
> - Joël