Re: [CFRG] Adoption Call: Guidelines for Writing Cryptography Specifications

I whole-heartedly support adoption. I think this would be a useful
resource. (I particularly like the idea of including a list of exemplary
specs and specs that didn't quite serve their purpose.)

I think my primary concern is that this draft touches on a few aspects of
spec writing that are somewhat subjective. In particular the draft uses the
term "formal" as if all readers have the same bar for what "formality"
entails. I'm not sure if anything can really be done about this, but there
may be specific instances where we can provide some concrete
recommendations.

Specific comments:

   1. Section 3.2 "Precision": It would be useful to cite specific examples
   where ambiguous specs (including those outside the CFRG) lead to security
   vulnerabilities.
   2. Section 3.2 "Precision": "[use] formal notation or pseudocode": To me
   this feels too subjective. I realize this is the bikeshed of all bikesheds
   (for our community in particular), but I wonder if it could/should be in
   scope for a draft like this to come up with a concrete recommendation. It
   would be wonderful if all or many CFRG drafts used the same language. (I
   think a similar point can also be made about mathematical notation, though
   there I feel less strongly: consistency throughout the document, and clear
   definitions, are sufficient.)
   3. Section 4.2.2 "Formalizing Security Definitions":  "Specification
   authors should strive to express security definitions in a formal
   language": What bar are you trying to get spec authors to cross here? Like,
   "the ciphertext does not leak the plaintext" is pretty informal; "the
   ciphertext is computationally indistinguishable from a random string" is
   more formal; (forall A)(forall poly) Pr[A(C<-$Enc(K,M)) => 1] - Pr[A($) =>
   1] < poly is even more formal.

Best,
Chris P.

On Thu, Jun 1, 2023 at 10:14 PM Stanislav V. Smyshlyaev <smyshsv@gmail.com>
wrote:

> Dear CFRG participants,
>
> This message is starting 3 weeks adoption call on "Guidelines for Writing
> Cryptography Specifications" draft,
> draft-sullivan-cryptography-specification-00 (
> https://datatracker.ietf.org/doc/draft-sullivan-cryptography-specification/)
> that will end on June 23rd 2023.
>
> Please send your feedback in reply to this email or directly to CFRG
> chairs <cfrg-chairs@ietf.org> <cfrg-chairs@ietf.org>.
>
> Best regards,
> Stanislav (for CFRG chairs)
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