[mswphd]

you would make poor decisions then. McEliece recently (in the last month) had a large new attack against it

https://eprint.iacr.org/2026/1232

This doesn't hit classic McEliece yet, but is part of a line of work that Randriambololona has been doing, which are at a minimum very concerning for the security of McEliece.

[teravor]

certainly a concern, and a good reason to use multiple cryptosystems together. unfortunately there are probably similar papers for Kyber which are NSA property and will never see the light of day. they do employ a lot of mathematicians.

for applications where key exchange need not be particularly fast or compact, I would even throw in 4096 MP-RSA in (tuned to whatever size the exchange can tolerate) as a hedge against that if a CRQC is even possible, it would be able to continue to grow in size quickly or at all.

[mswphd]

there is no indication there are similar papers. Curiously, the best lattice cryptanalysts in the world are chinese and european (here I'm thinking of people like Ducas, Albrecht, and Ding). It's actually a weird blindspot of american cryptography (this isn't true for all cryptanalysis, but in general European cryptography is "more concrete" vs "theoretical" american cryptography).

This isn't to say that it is impossible for the NSA to have their own private cryptanalysis. It is to say they're not some magical fairy that produces non-trivial attacks. They, like any other organization, need to develop talent. In the past they have been able to do this (they, through the CCR, hired Don Coppersmith in 2005. A VERY notable cryptanalyst at the time). I am unaware of any lattice cryptanalysts who have "gone dark" in a way similar to how Coppersmith did in ~2005.

Note that we also have theoretical reasons to be more confident in the hardness of ML-KEM. The reasons are technical (and worse than the practical reasons we have, namely people have iterated on attacks and the attacks stopped getting appreciably better). But it is (curiously) the hardness assumption we perhaps have the best (theoretical) justification for why it is hard.

Using RSA as a hedge would be incredibly stupid. Index calculus attacks were significantly improved in the 2010s, at least for small characteristic finite field DH. These improvements have only tangentially hit RSA. I've heard a integer factorization record holder directly say there's no real barrier to similar improvements hitting factoring. It hasn't been done, so it isn't "easy". But also people wouldn't be surprised if it was done. The record for binary characteristic finite field DH is ~30k bits (by an academic team. governments could throw more money at it of course).

[mswphd]

as a heads up, there is another attack paper against McEliece today

https://eprint.iacr.org/2026/1339

Note that this is by someone from the BSI. It's worth mentioning the BSI is very familiar with lattice-based schemes (they recommend using FrodoKEM rather than Kyber, but whatever). Despite this familiarity, the attacks they are able to publish aren't regarding lattice-based schemes, and instead a different scheme Bernstein was affiliated with.

NTRU-derivatives and McEliece derivatives are (objectively speaking) not a good track record to have, PQC-wise.