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#hybrids#nsa#djb#bernstein#standards#track#argument#cryptographers#https#mlkem

Discussion (43 Comments)Read Original on HackerNews

ifh-hn•39 minutes ago
Can someone ELI5 what the issue is here? I feel like I'm missing a lot of nuance here. Are the NSA people attempting to weaken TLS by removing ECC?
tptacek•31 minutes ago
No. This whole situation is extremely dumb.

Bernstein is a co-author on NIST PQC competition submissions that didn't win (Classic McEliece, which just had a huge new research result, and Streamlined NTRU Prime, a lattice cousin to MLKEM).

When CRYSTALS/Kyber was selected in the NIST competition instead of SNTRUP, Bernstein didn't take it well. He claimed malfeasance by NIST and sued them for allegedly hiding documents.

Meanwhile, over the subsequent years, the world has continued turning on its axes. CRYSTALS/Kyber is now ML-KEM. Because many cryptography engineers and other security people think there's a lot of urgency to getting PQC deployed (because of harvest-now decrypt-later [HNDL] attacks), the IETF got a move on standardizing hybrid ECDH/MLKEM TLS 1.3, which is what everyone uses.

Nobody at IETF has ever to my knowledge even hinted that anyone should avoid hybrids. There is a standards-track RFC defining ECDH/ML-KEM hybrids.

There are environments where hybrids are problematic. You won't likely use any of them ever. Some of them occur within the US Government, and some of them are on highly constrained platforms (people seem to disbelieve this is ever really a thing but I once gameovered a smart meter because its RF protocol only had like 16 bits of counter space for CTR).

Because of this, there is also a proposed informational RFC --- not a standards track document --- that documents what pure MLKEM looks like in a TLS 1.3 setting. Bernstein's entire argument is that this is an NSA plot.

philodeon•about 2 hours ago
I enjoyed the @tptacek cameo. I suspect tptacek didn’t.
tptacek•about 2 hours ago
He didn't publicly call me an NSA shill, so I got off pretty easy. Obviously, I stand by what I said. I think it would be an understatement to suggest support for what Bernstein is arguing is a minority cause among cryptographers.
directoron•about 1 hour ago
The argument from Roberto Avanzi is reasonable: "as a codesigner of ML-KEM myself I would not trust using it exclusively: what if it gets broken mathematically and in the classical computational model (I.e. non-quantum)? Hybrid is better, and the additional time used by ECC is not significant."
tptacek•about 1 hour ago
A majority (but not a large majority) of cryptography engineers would use hybrids at this point, and hybrids are largely the default design for any mainstream deployment. Bernstein argument isn't "use hybrids, not pure MLKEM"; it's "MLKEM is so dangerous there shouldn't even be an informational standard saying how to use it". That's a problem, because there are non-mainstream deployment environments where you can't use hybrids.

Obviously, Bernstein is counting on you not following that level of nuance; he'd much rather you believe he's arguing for hybrids against people who are trying to exterminate hybrids.

For clarity: I am not a cryptographer; I'm a vulnerability researcher who does some cryptography work and for several reasons I talk to a lot of academic cryptographers and cryptography engineers. You could not pay me to design a PQC transport protocol for you.

cassonmars•about 1 hour ago
Are you a cryptographer?

I am. I literally hold six patents around secure key generation and management. I stand by DJB's points.

tptacek•about 1 hour ago
Amazing. Six patents! I sign literally everything I write here with my own name, so it's pretty easy to find out my background.
eis•about 1 hour ago
I'm confused by your messages linked by DJB. You say that better cryptographers would not choose hybrids, which seems to say that you should indeed think that hybrids are not a good choice. Then you say you are not such a good cryptographer and would choose a hybrid. But if you know that more senior cryptographers think they are not the right choice then why choose them anyways? Or am I misreading "cryptography-literate" here?

Can you explain a bit more regarding your statement that DJB's POV on the matter has no broad support amongst his peers? I'm not in the field but Bernstein seemed like a highly respected member with a long track record in the crypto community, at least from the outside. Do you think the community is wrong or is it DJB who's wrong and why? There's also a good chance that I totally missed the argument being made.

tptacek•about 1 hour ago
I can think of several academic cryptographers (or rather, practitioners with doctorates) who think the hybrid/pure thing is silly. I didn't claim that a majority oppose hybrids. The point of the message he snipped from the HN thread is that pure MLKEM is not considered an unserious design by actual cryptographers (people on the HN thread --- generally not cryptographers, like me --- think it is). Cryptography engineers tend to default to hybrids.

Downthread we develop more clarity about what it is Bernstein is actually in an argument about. It isn't hybrids vs. pure!

cassonmars•about 2 hours ago
frankly every time this topic comes up he's quick to try to spread disinformation on djb's posts, so it's about time he got mentioned
timschmidt•27 minutes ago
Every. Single. Time. And vehemently. Like clockwork, or a job.
philodeon•19 minutes ago
tptacek once adored djb. This changed around 2015-2016, when one of tptacek’s crypto acquaintances lost a grad school spot (studying under djb) to Jacob Appelbaum. This led her and a couple of her friends to accuse Appelbaum of sexual assault and grape.

tptacek wants to be seen as a good feminist ally because his feminist wife would castrate him otherwise. So, he #BelievedWomen, and part of that is making sure you shun the unbelievers. Thus, djb is to be criticized by tptacek at every opportunity.

alfiedotwtf•12 minutes ago
I thought this was going to be rehashing of the old NULL-cypher IPsec thread, but it’s a different thing.

Maybe we should treat standards like we do a free market - let anyone implement what they choose then let people chose which to adopt, but the main thing is get government out of the entire process.

If the government wants to standardise, that’s fine… just don’t make it an industry standard adopted by civilians. Let them have their weakened protocols will the market moves on

stackghost•about 3 hours ago
It's never been clear to me why NSA's "blue team" directorates haven't been spun off into a separate agency. Sure, NSA strengthened the S-boxes in DES and SHA-1 but from the outside there's no way to know whether they're making DES stronger against differential cryptanalysis or whether they're introducing a DUAL_EC-style vulnerability.

I'm sure there's a game-theoretic optimum choice when it comes to accepting proposals from the NSA vs rejecting them out of hand, but I'm not sure what that optimal choice is.

philodeon•about 2 hours ago
jauntywundrkind•about 3 hours ago
> I'm happy to report that 82 people spoke up on the TLS mailing list in unambiguous opposition to this spec during the voting period

How many of them spoke before on this mailing list, in any capacity what so ever? I suspect this is 99% people who showed up because you organized a brigadging, because you incited people and told them to show up and be completely outraged.

There's a >0% chance that DJB could be correct that there is some risk to this spec (which notably is not seeking recommendation status! So WTF?) The people approving and wanting this aren't fools, aren't lackies, aren't some great foe. There's little real opposition? Making up ghosts and enemies lurking in every corner, brigading people to show up in IETF meetings, who have never participated before, just to spread heat and anger you've programmed them for, is ignoble & indecent.

All too recently: https://news.ycombinator.com/item?id=48760490 https://news.ycombinator.com/item?id=48811887

cornstalks•about 2 hours ago
> which notably is not seeking recommendation status!

I don’t have a dog in this fight, but some extremely important RFCs are only on the “informational” track. RFCs 1945 (HTTP 1.0), 4627 (JSON), 2818 (HTTPS), etc.

tptacek•about 1 hour ago
HTTP, JSON, and HTTPS all have standards-track RFCs.
cornstalks•17 minutes ago
As far as I know HTTP 1.0 doesn't have a standards-track RFC (HTTP 1.1 and later do). JSON and HTTPS do indeed have standards-track RFCs, but I stand by my original wording that their first informational RFCs were "extremely important."
cassonmars•about 2 hours ago
because the NSA has never surreptitiously pushed bad standards they used to exploit before

/s

tptacek•about 1 hour ago
Which PQC standard are you suggesting they pushed, and how did they push it? Flesh the argument out.
vlovich123•about 1 hour ago
That’s a very unfair position to take when dealing with secret agencies who try very hard to obfuscate this stuff - it is hard to provide evidence for in the moment.

The government has intentionally acted to weaken DES, standardized Dual_EC_DRBG, performed subtle subterfuge through interfering how NIST operates to inject weaknesses and vulnerabilities, trying to weaken SSL and IPSec, 4G smartphone encryption.

These are all documented examples of the NSA engaging in bad faith. So whether or not it is happening in this particular case, there’s now just zero trust in the institutions acting in good faith. And given it took decades for the actions to come out after they were taken, how do you expect someone to answer your request to present evidence there’s anything nefarious happening now?

Anyway, that’s what I think a fleshed out argument would look like

timschmidt•12 minutes ago
Brings to mind this lovely quote from the Snowden documents:

“The road to developing this standard was smooth once the journey began... However, beginning the journey was a challenge in finesse ... After some behind-the-scenes finessing with the head of the Canadian national delegation and with C.S.E., the stage was set for N.S.A. to submit a rewrite of the draft ... Eventually, N.S.A. became the sole editor.”

https://macleans.ca/society/technology/nsa-says-it-finessed-...