Re: [openpgp] Curve3617 in OpenPGP? Beyond rfc6637.

Gregory Maxwell <gmaxwell@gmail.com> Fri, 18 October 2013 08:42 UTC

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Date: Fri, 18 Oct 2013 01:42:11 -0700
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From: Gregory Maxwell <gmaxwell@gmail.com>
To: Werner Koch <wk@gnupg.org>
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Cc: openpgp@ietf.org, Jon Callas <jon@callas.org>
Subject: Re: [openpgp] Curve3617 in OpenPGP? Beyond rfc6637.
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On Fri, Oct 18, 2013 at 1:29 AM, Werner Koch <wk@gnupg.org>; wrote:
> and actually it is faster to use because there is no need for
> uncompressing.

Not so at least for ECDH, e.g. the implementation in curve25519 uses a
multiplier that really does work on the X coordinate alone. For other
curves (which are not twist secure), generally time spent
uncompressing is not to much slower than the sqrt needed to check that
the point is on the curve.