[HelloNurse]

The metaphor near the beginning of the article is a good summary: standardizing cars with seatbelts, but also cars without seatbelts.

Since ML-KEM is supported by the NSA, it should be assumed to have a NSA-known backdoor that they want to be used as much as possible: IETF standardization is a great opportunity for a long term social engineering operation, much like DES, Clipper, the more recent funny elliptic curve, etc.

[blintz]

> Since ML-KEM is supported by the NSA, it should be assumed to have a NSA-known backdoor that they want to be used as much as possible

AES and RSA are also supported by the NSA, but that doesn’t mean they were backdoored.

[HelloNurse]

AES and RSA had enough public scrutiny to make backdooring backdoors imprudent.

The standardization of an obviously weaker option than more established ones is difficult to explain with security reasons, so the default assumption should be that there are insecurity reasons.

[blintz]

There was lots of public scrutiny of Kyber (ML-KEM); DJB made his own submission to the NIST PQC standardization process. A purposely introduced backdoor in Kyber makes absolutely no sense; it was submitted by 11 respected cryptographers, and analyzed by hundreds of people over the course of standardization.

I disagree that ML-KEM is "obviously weaker". In some ways, lattice-based cryptography has stronger hardness foundations than RSA and EC (specifically, average -> worst case reductions).

ML-KEM and EC are definitely complementary, and I would probably only deploy hybrids in the near future, but I don't begrudge others who wish to do pure ML-KEM.

[adgjlsfhk1]

I don't think anyone is arguing that Kyber is purposefully backdoored. They are arguing that it (and basically every other lattice based method) has lost a minimum of ~50-100 bits of security in the past decade (and half of the stage 1 algorithms were broken entirely). The reason I can only give ~50-100 bits as the amount Kyber has lost is because attacks are progressing fast enough, and analysis of attacks is complicated enough that no one has actually published a reliable estimate of how strong Kyber is putting together all known attacks.

I have no knowledge of whether Kyber at this point is vulnerable given whatever private cryptanalysis the NSA definitely has done on it, but if Kyber is adopted now, it will definitely be in use 2 decades from now, and it's hard to believe that it won't be vulnerable/broken then (even with only publicly available information).

[zahllos]

Source for this loss of security? I'm aware of the MATZOV work but you make it sound like there's a continuous and steady improvement in attacks and that is not my impression.

Lots of algorithms were broken, but so what? Things like Rainbow and SIKE are not at all based on the hardness of solving lattice problems.

[woodruffw]

> AES and RSA had enough public scrutiny to make backdooring backdoors imprudent.

Can you elaborate on the standard of scrutiny that you believe AES and RSA (which were standardized at two very different maturation points in applied cryptography) met that hasn't been applied to the NIST PQ process?

[zahllos]

SHA-2 was designed by the NSA. Nobody is saying there is a backdoor.

[basilgohar]

I think it's established that NSA backdoors things. It doesn't mean they backdoor everything. But scrutiny is merited for each new thing NSA endorses and we have to wonder and ask why, and it's enough that if we can't explain why something is a certain way and not another, it's not improbable that we should be cautious of that and call it out. This is how they've operated for decades.

[zahllos]

Sure. I'm not American either. I agree, maximum scrutiny is warranted.

The thing is these algorithms have been under discussion for quite some time. If you're not deeply into cryptography it might not appear this way, but these are essentially iterations on many earlier designs and ideas and have been built up cumulatively over time. Overall it doesn't seem there are any major concerns that anyone has identified.

But that's not what we're actually talking about. We're talking about whether creating an IETF RFC for people who want to use solely use ML-KEM is acceptable or not - and given the most famous organization proposing to do this is the US Federal Government it seems bizarre in the extreme to accuse them of backdooring what they actually intend to use for themselves. As I said, though, this does not preclude the rest of the industry having and using hybrid KEMs, which given what cloudflare, google etc are doing we likely will.

[cryptonector]

One does not place backdoors in hash algorithms. It's much more interesting to place backdoors in key agreement protocols.

[tptacek]

How would NSA have "placed" a backdoor in Kyber? NSA didn't write Kyber.

[zahllos]

I will reply directly r.e. the analogy itself here. It is a poor one at best, because it assumes ML-KEM is akin to "internetting without cryptography". It isn't.

If you want a better analogy, we have a seatbelt for cars right now. It turns out when you steal plutonium and hot-rod your DeLorean into a time machine, these seatbelts don't quite cut the mustard. So we need a new kind of seatbelt. We design one that should be as good for the school run as it is for time travel to 1955.

We think we've done it but even after extensive testing we're not quite sure. So the debate is whether to put on two seatbelts (one traditional one we know works for traditional driving, and one that should be good for both) or if we can just use the new one on the school run and for going to 1955.

We are nowhere near DeLoreans that can travel to 1955 either.

[MYEUHD]

> the more recent funny elliptic curve

Can you elaborate please?

[zahllos]

The commentor means Dual_EC, a random number generator. The backdoor was patented under the form of "escrow" here: https://patents.google.com/patent/US8396213B2/en?oq=USOO83.9... - replace "escrow" with "backdoor" everywhere in the text and what was done will fall out.

ML-KEM/ML-DSA were adapted into standards by NIST, but I don't think a single American was involved in the actual initial design.

There might be some weakness the NSA knows about that the rest of us don't, but the fact they're going ahead and recommending these be used for US government systems suggests they're fine with it. Unless they want to risk this vulnerability also being discovered by China/Russia and used to read large portions of USG internet traffic. In their position I would not be confident that if I was aware of a vulnerability it would remain secret, although I am not a US Citizen or even resident, and never have been.

[johncolanduoni]

Not that I think this is the case for this algorithm, but backdoors like the one in Dual_EC cannot be used by a third party without what is effectively reversing an asymmetric key pair. Their public parameters are the product of private parameters that the NSA potentially has, but if China or whoever can calculate the private parameters from the public ones it’s broken regardless.

[zahllos]

Indeed. Dual_EC was a NOBUS backdoor relying on the ECDLP. That's fair.

My point was more that it looked suspicious at the time (why use a trapdoor in a CSPRNG) and at least the possibility of "escrow" was known, as evidenced by the fact that Vanstone (one of the inventors of elliptic curve cryptography) patented said backdoor around 2006.

This suspiciousness simply doesn't apply to ML-KEM, if one ignores one very specific cryptographer.

[rdtsc]

Not op, but they probably meant https://en.wikipedia.org/wiki/Dual_EC_DRBG