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Re: [TLS] Curve25519 in TLS and Additional Curves in TLS

Andy Lutomirski <luto@amacapital.net> Thu, 23 January 2014 18:53 UTC

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From: Andy Lutomirski <luto@amacapital.net>
Date: Thu, 23 Jan 2014 10:52:59 -0800
Message-ID: <CALCETrV=eKu25+bdBA-e0hMPXp8PP=2+zRAnMdsgXbBv87RmKQ@mail.gmail.com>
To: "Salz, Rich" <rsalz@akamai.com>
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Cc: Manuel Pégourié-Gonnard <mpg@polarssl.org>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Curve25519 in TLS and Additional Curves in TLS
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On Thu, Jan 23, 2014 at 10:46 AM, Salz, Rich <rsalz@akamai.com> wrote:
>> Can someone remind me why any of the above is better than using ECPointFormat to specify the point format?
>
> Because ECPoinrtFormat requires X and Y cords and Curve25519 has no Y.
>

Why is "defined by the curve" (where said definition may not actually
allow x and y to be computed) less of a departure from the current
ECPointFormat than, say, "Montgomery form x and sign bit of Edwards
form x"?  It's already the case that not all point formats are
applicable to all curves.

> There is discussion about having a "defined by the curve" ECPointFormat; how to move such a proposal forward is being discussed by the Security Area Directors, who owe as a response "soon" (see http://www.ietf.org/mail-archive/web/tls/current/msg11139.html )
>
>         /r$
>
> --
> Principal Security Engineer
> Akamai Technology
> Cambridge, MA



-- 
Andy Lutomirski
AMA Capital Management, LLC

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