NSA and IETF: Fairness

I can't help but note two things:

* the IETF's approach predates 15 U.S.C. §4302 by more than a decade

* every single case example cited is US-American scoped¹ SDOs: American Society of Mechanical Engineers, National Fire Protection Association, American National Standards Institute²

¹ NB scope ≠ legal domicile. The IETF's legal status is… complicated… but does have US dependencies. Its scope is world-wide though. Not so for any of the mentioned entities, even if…

² …ANSI is a borderline case since it is the constituent ISO member. But still, it's the US entity.

I'm not trying to make a legal argument here, but… I'll say he shouldn't be trying to do that either. Most mathematicians and CS majors make very poor lawyers in any case, and often enough without any awareness of it.

To point out some positive examples of what RFCs should include:

RFC 5288 s3 (AES-GCM): "Each value of the nonce_explicit MUST be distinct for each distinct invocation of the GCM encrypt function for any fixed key. Failure to meet this uniqueness requirement can significantly degrade security."[1]

RFC 7748 s5 (X25519): "The cswap function SHOULD be implemented in constant time (i.e., independent of the swap argument)."[2]

By contrast, this proposed RFC for MLKEM provides a single encouragement:

"[NIST-SP-800-227] includes guidelines and requirements for implementations on using KEMs securely. Implementers are encouraged to use implementations resistant to side-channel attacks, especially those that can be applied by remote attackers."[3]

It's not even a SHOULD, it's just an encouragement in a non-normative section of the RFC.

When you go to the referred NIST SP 800-227 it then tells you it's all too hard anyway and good luck and have fun figuring it out yourself:

"Cryptographic modules for KEMs should be designed with appropriate countermeasures against side-channel attacks. This includes protecting against timing attacks with constant-time implementations and protecting memory from leakage. Universal guidelines are unlikely to be helpful as exposure to side-channel attacks varies significantly with the desired application, and countermeasures are often costly."[4]

The normative standard FIPS 203[5] which the draft MLKEM RFC relies upon NEVER mentions "side channel", "constant", "timing" or provides any other assistance to implementers on how to securely multiply and/or divide numbers on computers or how to deal with conditional branching. Fair enough it includes a lower case "should" for considering side-channel resistance, but this throwaway comment is inadequate for standardisation.

The main reason it is inadequate is, imagine you're on your Hardened Gentoo or some other uber-geek laptop with the most advanced and thoroughly tested side channel resistant MLKEM client imaginable. You want to access your bank's website that offers MLKEM-only TLS. You don't have any assurance the bank's implementation of MLKEM has implemented any side channel resistance because the RFC they claim to have implemented never required it. If you then extrapolate from historical woes of implementing side channel resistant crypto (ECDSA scalar multiplication for example), it's probably correct to assume someone has, or reasonably could at some point in the future, extract private keys from the bank's side, and thus your expectations of having a secure connection are unmet. This is a standardisation problem because two implementations cannot agree on whether the protocol offers any resistance to side channel leakage to remote adversaries, therefore, what is the security guarantee the two implementations can actually agree upon?

The key missing section of this RFC is perhaps a restriction on its application similar to:

"This standard does not require implementations to consider side-channel attacks. This standard SHOULD NOT be used for protecting data and communications where an adversary may have one or more of: a) physical access to equipment performing cryptographic operations and time and resources necessary to observe physical properties of the equipment (power and signal characteristics, electromagnetic radiation, thermal dissipation), b) ability to execute code on equipment performing cryptographic operations, c) remote access to high-resolution monitoring data of physical properties of equipment performing cryptographic operations, d) ability to observe and/or establish a session to a party using this cryptographic protocol."

Thus it'd only be applicable to low risk environments such as two servers in a government building in separate rooms where an adversary is prevented from conducting a side channel attack by a plethora of other security controls.

[1] https://datatracker.ietf.org/doc/html/rfc5288#section-3

[2] https://datatracker.ietf.org/doc/html/rfc7748#section-5

[3] https://datatracker.ietf.org/doc/draft-ietf-tls-mlkem/

[4] https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.S...

[5] https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.203.pdf

Unfortunately, that's not how modern crypto works. Many mathematical problems on which algorithm rests their security are not proven to be unsolvable, but instead they're believed to be hard to solve. So here are the questions, who believes what is hard, and hard for whom.

Somehow I wouldn't trust my data on mathematical problems, for which the recommendation is that they would challenge Kayne West.

[flagged]

I have edited my post to remove the rude acronym. Thank you for your feedback.

I do not think the response addresses the claims made, and uses logical fallacies in place of a well reasoned response.

> a team of highly-regarded European academic cryptographers

This is absolutely an appeal to authority.