It's a simple question. I'm not asking anybody to prove anything. I'm literally asking: propose the PQC standard IETF could have subverted, and give a sketch of how they could have done it. The bar is merely "plausibility". I'm not asking whether NSA has subverted standards before; obviously they have.

NSA, by the way, rescued DES from differential cryptography, the core mechanism by which block ciphers and hash functions have been attacked ever since.

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vlovich123 21 minutes ago | parent | next [-]

They did both - they strengthened it from differential integrity but weakened it by picking a known-to-be-too-short key length. Meaning they had the compute power to crack it but others couldn’t do the same through pure algorithmic means.

As for your post below

> it can't be that NSA simply knows a vulnerability that impacts one very specific lattice scheme and not the others

Ok. My argument is they know all lattice schemes are weak and the push to use a lattice-only scheme is precisely to have a cryptographic mechanism they can easily bypass without a classical known-secure backstop.

	▲	tptacek 13 minutes ago \| parent [-]
		See, here's another argument that doesn't work here, because Bernstein very publicly backs a different lattice cryptography scheme. In addition to the previously-stated reason why that argument is inoperative (besides being unfalsifiable, it admits a strategy where NSA "poisons the well" to get people to avoid a particular construction or family of algorithms, so that we all move to weaker ones --- a counterfactual that should be much more vivid after what was released this week!)

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Vecr 39 minutes ago | parent | prev [-]

> NSA, by the way, rescued DES from differential cryptography, the core mechanism by which block ciphers and hash functions have been attacked ever since

That's why you use ML-KEM 1024 at all... As part of a hybrid.

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tptacek 37 minutes ago | parent [-]

I don't know what this is, but it isn't an answer to the question. I'm starting to notice that nobody is able to come up with an answer.

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Vecr 29 minutes ago | parent [-]

There is no public reason to think that 1024 is better than 768, or DJB's S-NTRU-P 761. The NSA might know something, but we can't trust them. So, use a hybrid, in case they are really just trying to protect us.

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tptacek 26 minutes ago | parent [-]

That can't be the argument --- it can't be that NSA simply knows a vulnerability that impacts one very specific lattice scheme and not the others. The reason for that is a cryptographic concept known as the Vizzini Conjecture: the argument you just put forward can be applied to literally any cryptographic standard NIST authors. Since NSA knows that, and knows you know it, you can clearly not choose the wine in front of you. It must be that the standard NIST picks is the only secure one, so that NSA can see it tainted by NIST association.

But yes, this is the useful conversation to have. There are other scenarios! You can get into more detail on where MLKEM came from, for instance.

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Vecr 14 minutes ago | parent [-]

Yes, they trick me and I pick the poisoned wine... But wait, no, I used a hybrid. Imagine the code can't be backdoored (it's proven not to crash/be slow/be exploitable) so at worst it can make the security no better. At best, the NSA knows a whole new subfield of cryptography (from history: differential cryptanalysis) and it really is more secure.

They laugh at us while we try to think of how 1024 is better than 768: "bigger is better, right?" "does 1024 refer to the number of years it takes Nightmare Moon to break the code?"

	▲	tptacek 12 minutes ago \| parent [-]
		There is nobody at IETF saying you shouldn't use a hybrid! In fact, it's the exact opposite: hybrid ECDH/MLKEM is a standards-track RFC, and the proposed pure-MLKEM RFC is not, nor is it "Recommended" (in IETF parlance). Let's keep the thread coherent: the original claim, by cryptographer 'cassonmars, is that the issue here is NSA pushing bad standards. It's not "hybrid vs. pure", which is a non-issue. All I asked for was a plausible story about how NSA might have pushed a bad PQC standard.