Re: [Cfrg] On the use of Montgomery form curves for key agreement

Watson Ladd <watsonbladd@gmail.com> Tue, 02 September 2014 15:19 UTC

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Date: Tue, 2 Sep 2014 08:19:50 -0700
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From: Watson Ladd <watsonbladd@gmail.com>
To: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Subject: Re: [Cfrg] On the use of Montgomery form curves for key agreement
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On Tue, Sep 2, 2014 at 1:30 AM, Stephen Farrell
<stephen.farrell@cs.tcd.ie>; wrote:
>
> Just on this point...
>
> On 02/09/14 02:50, Benjamin Black wrote:
>> The various working groups and standards bodies have already answered the
>> question of what goes on the wire.
>
> That's not correct. When CFRG finish doing a great job here, then
> the TLS WG will have to assign new codepoints for ciphersuites and
> there is nothing stopping them defining new encodings at that point
> if that's needed. That'd just not be a big deal. And the same is
> true of other IETF activities. So what goes on the wire should be
> a non-issue for this discussion really.

Aren't we replacing SEC1? And doesn't SEC1 specify encodings, which
other WGs use?

If we end up saying "pairs of integers" then we get a mess, where
software implementing the curves has to implement a large number of
encodings. If we specify things as strings of bytes, that's easy to
deal with. I've heard some people say this was a mistake, but I am
unconvinced by those arguments.

Sincerely,
Watson Ladd


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