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[TLS] Re: Working Group Last Call for Post-quantum Hybrid ECDHE-MLKEM Key Agreement for TLSv1.3

Viktor Dukhovni <ietf-dane@dukhovni.org> Fri, 10 October 2025 06:23 UTC

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Date: Fri, 10 Oct 2025 17:23:22 +1100
From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: [TLS] Re: Working Group Last Call for Post-quantum Hybrid ECDHE-MLKEM Key Agreement for TLSv1.3
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On Tue, Oct 07, 2025 at 09:39:52AM -0700, Eric Rescorla wrote:

> For context, there are currently four such supported groups for TLS:
> X25519, X448, P-256, and P-384. Is there a substantive reason why the
> hybrids of these same groups with MLKEM ought not to be RECOMMENDED=Y?

I was just drafting a message to suggest that the draf is missing an
obvious combination:

    MLKEM1024 + X448

If MLKEM1024 is supported with SecP384r1 (P-384), it should also be
supported with X448.  The supported combinations would then be more
"natural":

    MLKEM768 + either P-256 or X25519
    MLKEM1024 + either P-384 or X448

-- 
    Viktor.  🇺🇦 Слава Україні!

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