[km-fs-pcs] Re: Relation to "MLS Targeted Messages"

Gaëtan Wattiau <gaetan.wattiau@proton.me> Fri, 19 June 2026 19:38 UTC

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Date: Fri, 19 Jun 2026 19:35:59 +0000
To: Raphael Robert <ietf=40raphaelrobert.com@dmarc.ietf.org>
From: Gaëtan Wattiau <gaetan.wattiau@proton.me>
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Subject: [km-fs-pcs] Re: Relation to "MLS Targeted Messages"
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Ok! Thanks for the quick reply.

I think what I don't understand is why this RFC is so specifically bound to the two-party profile, instead of a more generic: "this is how we generate and roll TLS session keys with MLS". Explaining the rationale for this scope in the introduction would be helpful to newcomers like me.

Gaëtan

On Friday, June 19th, 2026 at 7:08 PM, Raphael Robert <ietf=40raphaelrobert.com@dmarc.ietf.org> wrote:

> MLS targeted messages are not a replacement for the MLS 2 party profile, they are really different things.
>
> MLS targeted messages wouldn’t make much sense in a 2 party setting, they were designed for groups with more than two members, because their purpose is to encrypt messages between exactly two members so that the other n-2 members cannot decrypt it.
>
> In other words, there’s no relationship to MLS targeted messages whatsoever. Thank you for the question though, this shows that the text in the current draft could maybe be improved.
>
> Raphael
>
>> On 19. Jun 2026, at 19:28, Gaëtan Wattiau <gaetan.wattiau=40proton.me@dmarc.ietf.org> wrote:
>>
>> I just read the MLS-TLS draft, and my understanding is that it is currently centered on a two-party with a two-party profile.
>>
>> Have you considered a direction where this stays conceptually 1:1 at the messaging layer, but within an MLS group, using something like targeted messages [1] rather than MLS two-party profile?
>>
>> Best,
>>
>> Gaëtan Wattiau
>>
>> [1]: https://datatracker.ietf.org/doc/draft-ietf-mls-targeted-messages/
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