Re: [Cfrg] Point format endian (was: Adoption of draft-ladd-spake2 as a RG document)

"Dan Harkins" <dharkins@lounge.org> Fri, 23 January 2015 22:44 UTC

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Date: Fri, 23 Jan 2015 14:44:10 -0800 (PST)
From: "Dan Harkins" <dharkins@lounge.org>
To: "Alyssa Rowan" <akr@akr.io>
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Cc: "cfrg@irtf.org" <cfrg@irtf.org>
Subject: Re: [Cfrg] Point format endian (was: Adoption of draft-ladd-spake2 as a RG document)
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On Mon, January 19, 2015 4:27 am, Alyssa Rowan wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
>
> On 19 January 2015 11:56:27 GMT+00:00, "Dearlove, Christopher (UK)"
> <chris.dearlove@baesystems.com>; wrote:
>> […] Is the use of little endian format here a deliberate design
>> decision?
>
> Probably yes, to match every existing implementation of Curve25519 already
> in the wild (and most commonly-used architectures)?

  So a long-standing tradition of the on-the-wire format is changed because
of the way the first curve25519 library was written? That's a weak
justification.

  Dan.

> TLS WG give new curves free reign on point format, explicitly not SEC1
> constrained. They preferred little endian (weakly) for the above reason, I
> believe?
>
> - --
> /akr
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