NSA and IETF: Fairness(blog.cr.yp.to) |
NSA and IETF: Fairness(blog.cr.yp.to) |
(1) MLKEM wasn't designed by NSA, but rather by a team of highly-regarded European academic cryptographers, including Bernstein's former collaborator Peter Schwabe; their submission, Kyber, was selected in an open competition in which Bernstein himself submitted a closely-related algorithm (and then contested the result, suing NIST for documents to clarify the selection.)
(2) The RFC at issue documents the possibility of running TLS with pure MLKEM rather than in a hybrid configuration with ECDH. Hybrid TLS is already the mainstream, documented, standardized method for using PQC in a TLS connection. Bernstein is canvassing opposition to any documentation of the possibility of pure MLKEM in TLS.
Every time Bernstein talks about NSA's sordid history, remember: nothing that's happening here has really anything to do with NSA. It would make more sense for Bernstein to be canvassing against SHA2, which NSA actually did design. But he can't do that, because normal people know enough about cryptography to understand how crazy a claim that is. Unfortunately, we can't yet say that about lattice cryptography, despite it being approximately as well-studied as ECC.
Two more pieces of context here: 1. The IETF allows code point registrations based purely on the existence of a specification, and the pure ML-KEM code points have already been assigned (https://www.iana.org/assignments/tls-parameters/tls-paramete...). The question at hand is whether the IETF will publish an RFC documenting the ML-KEM cipher suites [edited to make clear that ML-KEM is documented already].
2. It is also possible to publish an RFC via what's called "Independent Submission" (https://www.rfc-editor.org/authors/rfc-independent-submissio...), which is not subject to the IETF Consensus process. This is, for instance, how the GOST RFC (https://datatracker.ietf.org/doc/rfc9367/) was published. If the IETF opts not to publish this draft, the authors can still submit it to the Independent Submissions Editor.
Further the draft that this is all about does not make a recommendation for its use. The currently IETF-recommended TLS algorithms are: X25519MLKEM768, x448, x25519, secp384r1, secp256r1.
As noted by someone on the IETF list [1] there are already ML-KEM-only implementations in various libraries, so if we want interoperability then it's best to have a standard document. No one is forcing anyone to use this algorithm, and it's not even 'officially' recommended (per above).
[1] https://mailarchive.ietf.org/arch/msg/tls/SXo4iVmp0ng_vi57ce...
The IETF document only documents how and where to put the MLKEM values into TLS. MLKEM itself is specified in FIPS203 and it just references that for the actual cryptographic details. The IETF document is in fact quite short:
https://www.ietf.org/archive/id/draft-ietf-tls-mlkem-08.html
(This doesn't mean the document is a stub or pointless or something like that, you do need a "what goes where".)
> Unfortunately, we can't yet say that about lattice cryptography, despite it being approximately as well-studied as ECC.
ML-KEM -- Module-Lattice-Based Key-Encapsulation Mechanism
ML-DSA -- Module-Lattice-Based Digital Signature Algorithm
solo PQ -- Using post-quantum crypto on its own
ECC+PQ -- Using post-quantum crypto as a layer on top of traditional elliptical curve cryptography (ECC)
So what's at stake here, is that the PQ crypto is not proven yet, and had recent implementation vulnerabilities (Kyberslash 1 & 2).
In the NSA's defense, combining cryptosystems also creates attack surfaces, timing problems, additional complexity, etc. Perhaps they know something we don't. They have sometimes acted to strengthen public cryptography, as with the DES S-boxes and differential cryptanalysis. Of course, they also weakened the key-space...
Is this true? The NSA pushed for weaker cryptography it could break versus stronger cryptography our adversaries couldn't?
Four days ago: https://news.ycombinator.com/item?id=48760490
If the link goes down, the content is available in many other places across the web under the title "The Gentleman's Guide To Forum Spies (spooks, feds, etc.)"
https://www.itu.int/en/ITU-T/tutorials/202203/Documents/Rein...
Apart from that, the crux of this is the codepoint allocation in the named group registry. [https://www.iana.org/assignments/tls-parameters/tls-paramete...] The requirement for that allocation (with "recommended=N" - which is what this draft has) is "Specification Required", not "IETF consensus". "Specification" for IANA registries doesn't mean IETF documents, it means:
[…] must be documented in a permanent and readily
available public specification, in sufficient detail so that
interoperability between independent implementations is possible.
As such I don't understand why the authors are so intent at ramming this through the IETF process when they could just put the same document whereever. The process has been sufficiently and publicly fraught enough to destroy any "reputation" that might (or might not) come associated with it being published as IETF RFC.
[ed.: referenced wrong registry, it's named groups, not cipher suites. Makes no difference, same registration procedure.]
FTR, the only [preliminary] entry with recommended=Y for PQ crypto is:
4588 X25519MLKEM768 Combining X25519 ECDH with ML-KEM-768 https://datatracker.ietf.org/doc/html/draft-ietf-tls-ecdhe-mlkem-05
The hybrid code point you reference is "preliminary" in the sense that when the RFC for hybrid ECC/ML-KEM is published (it's already been approved, https://datatracker.ietf.org/doc/draft-ietf-tls-ecdhe-mlkem/), it will replace the reference in the registry. However, it will have the same code point and the same semantics. If, for some reason, the IETF were to change the semantics, a new code point would have to be assigned for interop reasons.
Yes, sorry, I was just covering against people nitpicking on the document status :)
Participants in disputes and RFCs literally call their comments “!vote” in true hacker notation, to repeatedly and clearly emphasize that “vote count” is never a factor in the process of establishing consensus.
(Elections are, however, regularly held, and votes counted, for positions such as Administrator, and the ArbCom seats, but that’s for people, not article content.)
Which is why I'm noting the alienation of "IETF believers", which I should maybe clarify I count myself as. The IETF is a lot of people doing a lot of good work. It does include a bunch of questionable actors, anything from ignorant, incompetent, ulterior motives, to outright malicious. But all in all it has brought us the internet as it exists today and I can't help feeling a little, well, alienated by DJB's writs.
If the document is dropped by the IETF, nothing at all would happen. It's already a valid code point registration, and indeed the authors could have just published the document, registered the code points, and stopped (see: https://datatracker.ietf.org/doc/draft-barnes-tls-this-could...).
If the authors decided to later pick up the document somewhere else, then they could probably get the reference changed to whatever that was, as long as the semantics were identical.