Re: [Cfrg] [saag] A proposal for compact representation of an elliptic curve point (ECC point compression)

Russ Housley <housley@vigilsec.com> Wed, 12 December 2012 18:43 UTC

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From: Russ Housley <housley@vigilsec.com>
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Date: Wed, 12 Dec 2012 13:43:39 -0500
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To: Dan Brown <dbrown@certicom.com>
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Cc: 'Andrey Jivsov' <openpgp@brainhub.org>, "cfrg@irtf.org" <cfrg@irtf.org>, "saag@ietf.org" <saag@ietf.org>
Subject: Re: [Cfrg] [saag] A proposal for compact representation of an elliptic curve point (ECC point compression)
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Dan:

OCTET STRING was chosen to avoid the need to carry an extra byte to make the sign bit a zero.

Russ


On Dec 12, 2012, at 1:40 PM, Dan Brown wrote:

> My belief is that octet strings, rather than integers, were chosen (long before I was involved) for these formats because (at least partly, and perhaps mainly) these standards also allowed other finite fields (binary and odd characteristic extension fields), which are not naturally represented by integers.