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

["D. J. Bernstein" <[e-mail]>]

Jan Schaumann writes:
> I don't think I can follow a logic that says
> X25519MLKEM768 should be recommended, but not the
> others (unless one were to imply that standalone P-256
> and P-384 should not be recommended).

For me, the central point is that P-256 and P-384 create neverending
real-world implementation failures, such as CVE-2023-6135 in Firefox.
This is an argument against standalone P-256 and P-384 as well as this
draft's SecP256r1MLKEM768 and SecP384r1MLKEM1024.

For standalone P-256 in particular, the current status---mandated, and
according to some reports still used by 10% of TLS sessions---means that
the deprecation process should be gradual, starting with announcing the
plan, mandating a replacement, tracking deployment trends, etc.

Standalone P-384 is easier to get rid of: it's not needed for getting
data through, and it has far less usage in the first place.

As for SecP256r1MLKEM768 and SecP384r1MLKEM1024 in this draft, the
current status is that they're basically not supported in deployments at
all. The claims that these are needed for compliance don't seem to have
withstood examination. So I'm puzzled as to why they're there.

---D. J. Bernstein


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