Re: [MLS] Proposal: Proposals (was: Laziness)

Stephen Farrell <stephen.farrell@cs.tcd.ie> Fri, 23 August 2019 14:21 UTC

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To: Richard Barnes <rlb@ipv.sx>
Cc: Messaging Layer Security WG <mls@ietf.org>, Raphael Robert <raphael=40wire.com@dmarc.ietf.org>
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From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Date: Fri, 23 Aug 2019 15:21:05 +0100
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Subject: Re: [MLS] Proposal: Proposals (was: Laziness)
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Hiya,

On 23/08/2019 15:10, Richard Barnes wrote:
> 
> I'm not clear on what you mean by "meaningfully handled by members".
> 

I'm assuming that MLS protocol data will likely be
handled by a library. ISTM more likely that such a
library might default to, or be carelessly used to,
honor anything the server proposes if this is an MLS
protocol feature rather than an application layer
feature. That'd be an example of not meaningfully
handling this:-) We have seen similar kinds of
failure with applications and TLS libraries in the
past where certs aren't checked etc.

I do accept the argument that it can happen at the
application layer if not defined in the MLS protocol,
but doing this kind of thing at the application layer
seems safer to me.

It's also not clear to me that all MLS applications
would need this feature. (That may be true, I just
don't know.) If they don't, then again, it seems to
be more conservative to leave it to applications.

I agree that there are sharp edges however this kind
of thing is done though.

Cheers,
S.