Re: [Cfrg] PAKE Selection Process: Round 2, Stage 2

Watson Ladd <> Mon, 09 December 2019 15:41 UTC

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From: Watson Ladd <>
Date: Mon, 9 Dec 2019 07:41:17 -0800
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To: "Stanislav V. Smyshlyaev" <>
Cc: CFRG <>,
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Subject: Re: [Cfrg] PAKE Selection Process: Round 2, Stage 2
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On Mon, Dec 9, 2019 at 4:44 AM Stanislav V. Smyshlyaev <>

> Dear CFRG,
> According to the plan of Round 2 of the PAKE selection process, additional
> questions for all four remaining candidates have been collected from CFRG
> participants (and Crypto Review Panel members) via .
> We've obtained the following list of questions:
> 1) (to SPAKE2): Can you propose a modification of SPAKE2 (preserving all
> existing good properties of PAKE2) with a correspondingly updated security
> proof, addressing the issue of a single discrete log relationship necessary
> for the security of all sessions (e.g., solution based on using
> M=hash2curve(A|B), N=hash2curve(B|A))?

Yes: See and for the security
proof, I'll submit it shortly, but this
should indicate where we are going.

2) (to CPace and AuCPace): Can you propose a modification of CPace and
> AuCPace (preserving all existing good properties of these PAKEs) with a
> correspondingly updated security proof (maybe, in some other security
> models), addressing the issue of requiring the establishment of a session
> identifier (sid) during each call of the protocol for the cost of one
> additional message?
> 3) (to all 4 remaining PAKEs) : Can the nominators/developers of the
> protocols please re-evaluate possible IPR conflicts between their
> candidates protocols and own and foreign patents? Specifically, can you
> discuss the impact of U.S. Patent 7,047,408 (expected expiration 10th of
> march 2023) on free use of SPAKE2 and the impact of EP1847062B1 (HMQV,
> expected expiration October 2026) on the free use of the RFC-drafts for

I'm not a patent lawyer, or any kind of lawyer. This sounds like a question
for a patent lawyer, rather then uninformed speculation on the list.

4) (to all 4 remaining PAKEs) What can be said about the property of
> "quantum annoyance" (an attacker with a quantum computer needs to solve
> [one or more] DLP per password guess) of the PAKE?

I'll have to look at the papers some more. Will answer in a few days.

5) (to all 4 remaining PAKEs) What can be said about "post-quantum
> preparedness" of the PAKE?

There isn't a great answer here for SPAKE2 AKAIK. Postquantum primitives
don't smoothly translate point addition or group laws.

> Please let the chairs and the Crypto Review Panel members know (before
> December, 17th) if any questions (collected via
> have been lost or misinterpreted (or something needs to be added).
> Best regards,
> Stanislav,
> CFRG Secretary
> _______________________________________________
> Cfrg mailing list