Re: [Cfrg] using hash2curve in a protocol

Watson Ladd <watsonbladd@gmail.com> Thu, 25 July 2019 22:19 UTC

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From: Watson Ladd <watsonbladd@gmail.com>
Date: Thu, 25 Jul 2019 15:19:40 -0700
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To: Dan Harkins <dharkins@lounge.org>
Cc: "cfrg@irtf.org" <cfrg@irtf.org>
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Subject: Re: [Cfrg] using hash2curve in a protocol
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On Wed, Jul 24, 2019 at 11:05 AM Dan Harkins <dharkins@lounge.org>; wrote:
>
>
>    Hello,
>
>    The hash-to-curve draft is still a work in progress but I want to
> use it to fix a broken protocol. The protocol in question is EAP-pwd
> defined in RFC 5931. It does a "hunting and pecking loop" method
> of hashing to a curve that is similar, but worse, than the technique
> described in RFC 7664. (The method of obtaining a secret element in
> a MODP group is similarly broken). It is susceptible to side channel
> attack and I want to use the hash-to-curve draft to fix it.

Why not use a PAKE that comes out of the competition? And are you sure
the result of your chosen modification is actually secure?