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[TLS] Re: WG Last Call: draft-ietf-tls-mlkem-08 (Ends 2026-07-08)

Peter C <Peter.C@ncsc.gov.uk> Sun, 05 July 2026 12:03 UTC

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From: Peter C <Peter.C@ncsc.gov.uk>
To: "tls@ietf.org" <tls@ietf.org>
Thread-Topic: [TLS] Re: WG Last Call: draft-ietf-tls-mlkem-08 (Ends 2026-07-08)
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Subject: [TLS] Re: WG Last Call: draft-ietf-tls-mlkem-08 (Ends 2026-07-08)
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Bas Westerbaan wrote:
> Would you mind explaining how an attacker would use a timing side-
> channel attack against ephemeral use of ML-KEM in TLS?

This point cannot be emphasised enough. Client-side ephemeral key
generation already mitigates many potential ML-KEM implementation
vulnerabilities.

Take the faulty re-encryption check in CVE-2026-6330 as an example.
Exploiting this would require the client to initiate hundreds of
TLS connections with an attacker-controlled server using the same
key pair, where a significant proportion of those connections fail
giving a decrypt_error. It doesn’t seem plausible to me that this
could happen without being noticed and immediately fixed.

Peter

----

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result in a gentle head shake and sigh. Thanks in advance!

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