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NIST announces first PQC algoritms to be standardized

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Re: NIST announces first PQC algoritms to be standardized

#81
post #67

Earlier quoted context omitted.

It's hard to say. Here is a great paper that tries to answer this question. https://arxiv.org/pdf/2009.05045v1.pdf See Figure 11. Optimistically 15 years. Pessimistically 35 years. But anything can happen.

The linked study is about RSA, not elliptical curve cryptography

Does that matter? Both are based on some hidden subgroup problem and both are breakable in a similar way.

Re: NIST announces first PQC algoritms to be standardized

#82
post #67

Earlier quoted context omitted.

It's hard to say. Here is a great paper that tries to answer this question. https://arxiv.org/pdf/2009.05045v1.pdf See Figure 11. Optimistically 15 years. Pessimistically 35 years. But anything can happen.

The linked study is about RSA, not elliptical curve cryptography

It is generally accepted that elliptical curge cryptography is a bit easier to break with Shor's algorithm than RSA. Something like half as hard, but it probably would not make any real difference in practice. So the paper is directly applicable to elliptic curves to the extent that it is applicable to anything.

Re: NIST announces first PQC algoritms to be standardized

#83

HN Crypto and Quantum Experts. What is your prediction when classical public key encryption using elliptical curve cryptographic becomes practically vulnerable to quantum computers, such that we would need these PQC algorithms. 10 years out? 20 years out? 50 years out? 100 years out?

We have not been able to implement even a single logical qubit of the sort required to run Shor's algorithm (we would need thousands). It is impossible to extrapolate from zero.

Re: NIST announces first PQC algoritms to be standardized

#84
post #25

PQC = post quantum cryptography

Ah thank you. I figured the 'Q' stood for quantum but you saved me a fair amount of googling :)

"fair amount of googling"?

Not sure what browser you use, but in most you can select what you wanna search for, click "Search on $searchEngine for $term" and there you go! For PQC, I get Wikipedia link with "PQC can refer to: Post-quantum cryptography" in the description as the 3rd result on Google.

Not sure what classifies as "fair amount", but for me it took about 1-2 seconds to find the Wikipedia link ;)

Re: NIST announces first PQC algoritms to be standardized

#86

Earlier quoted context omitted.

If NIST feels the need to hedge their bets, why are they publishing at all? The whole point of these recommendations is so that I, a non-expert, don't have to reason about cryptographic bets.

Non-cryptographers should not be implementing NIST standards. You should be using higher level APIs written by cryptographers which do employ NIST standards in the details.

Implementing them for fun might turn you into a cryptographer, though, especially (or only?) if you manage to find everything you get wrong.

Re: NIST announces first PQC algoritms to be standardized

#87

> Additionally, SPHINCS+ will be standardized to avoid only relying on the security of lattices for signatures > Both BIKE and HQC are based on structured codes, and either would be suitable as a general-purpose KEM that is not based on lattices What's up with this caveat? Why would the standard require algorithms not based on lattices assuming there is confidence in the lattice based approach? Is this a security con…

A point rendering the choice even more curious: Germany and the Netherlands have recommended the use of encryption not relying on the shortest vector problem [1]. The two suggestions of FrodoKEM (relying on hardness of the learning with errors problem) and Classic McEliece (relying on hardness of decoding random codes?) aren't lattice-based apparently. Perhaps NIST knows something we don't ; ^ ) [1] - https://twitter…

LWE's hardness is based on SVP (ignoring issues of tightness, which isn't unique to FrodoKEM). The difference between FrodoKEM + Kyber/Saber isn't relying on SVP/not (they all essentially do), but is on relying on LWE over structured lattices or not.

At a very high level, all of the three rely on an n x n matrix at a certain point. The "structured lattice" schemes (Kyber/Saber) make structural assumptions about this matrix, say that each row is a cyclic shift of the previous row. This turns an O(n^2) object into an O(n) object, giving many performance improvements. The downside is that the additional structure can plausibly be used for attacks (but the best attacks ignore the structure, so this is a "potential issue", not a current issue).

Re: NIST announces first PQC algoritms to be standardized

#88
post #85
post #4

Obligatory djb warnings: https://ntruprime.cr.yp.to/warnings.html

Is djb involved in any of the standardized algorithms here by the way?

Yes, many. I believe he's on the SPHINCS+ team (was standardized), Classic McCliece (round 3, not standardized), and NTRU_PRIME (round 3, passed over for Kyber). Perhaps more, but he has significant skin in the game.

Re: NIST announces first PQC algoritms to be standardized

#89
post #72

Earlier quoted context omitted.

I it not tied to P vs NP as far as I’m aware. But it is the same sort of situation: number theory assumptions that are completely unproven despite many attempts.

I was thinking, if you could definitively prove these assumptions are hard, that would prove P != NP, because if P=NP that would imply there would be an algorithm to solve these types of problems, since they are the type of thing that can be solved in polynomial time with the key, but cannot without a key. (I'm a bit out of my depth here)

For the stuff underlying asymmetric keys, yes. The hash function stuff doesn’t have backdoors.

Re: NIST announces first PQC algoritms to be standardized

#90
post #77

Earlier quoted context omitted.

I wrote up an introduction to a (severely unoptimized for pedagogical purposes) version of FrodoKEM https://mark-schultz.github.io/nist-standard-out/ It's the same base scheme as Saber/Kyber, although as Saber/Kyber are over algebraically structured lattices they are significantly more efficient.

Thanks for taking the time to write this up. But, woof, it's a bit more than ELI5. :) The python code makes it a little more clear since I'm not familiar with some of the notation. However, it does seem kind of magic that 'e' is derived during the encryption and then sort of vanishes. I also don't quite get the bounded vs uniform vector sampling calls (one for s and the other for chi). But this at least greases the w…

Thanks for the feedback! Roughly speaking, that all has to do with making e vanish later, so perhaps I need to revisit that section.

Quickly (cause I probably won't for a few days), (q//2)m can be seen as a form of error correction. You can check (either pen+paper or programmatically) that, provided |e| m + e, then round(noisy_m / (q/4)) = m. So e vanishes because it is bounded (not uniform), + we encode m as (q//2)*m (i.e. in the "most significant bits" of the number).

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