Re: [Cfrg] Adoption of draft-ladd-spake2 as a RG document

Paul Lambert <paul@marvell.com> Thu, 22 January 2015 19:59 UTC

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From: Paul Lambert <paul@marvell.com>
To: Adam Langley <agl@imperialviolet.org>, "Dearlove, Christopher (UK)" <chris.dearlove@baesystems.com>
Date: Thu, 22 Jan 2015 11:59:01 -0800
Thread-Topic: [Cfrg] Adoption of draft-ladd-spake2 as a RG document
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Subject: Re: [Cfrg] Adoption of draft-ladd-spake2 as a RG document
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On 1/22/15, 11:35 AM, "Adam Langley" <agl@imperialviolet.org>; wrote:

>On Mon, Jan 19, 2015 at 3:56 AM, Dearlove, Christopher (UK)
><chris.dearlove@baesystems.com>; wrote:
>> A minor point compared to choice of curve. Commenting on draft
>>draft-agl-cfrgcurve-00, it indicates, in section 8 the use of
>>little-endian order. RFC 5480 (obvious prior art in IETF) does not
>>appear to specify big/little endianness, but delegates that to its
>>reference SEC1. That document (http://www.secg.org/sec1-v2.pdf) in
>>section 2.3.7 reverses the order of its x and M coefficients to produce
>>a big-endian representation of an integer. Big endian format is also
>>used by, for example, OpenSSL. Is the use of little endian format here a
>>deliberate design decision?
>
>(This appears to be a comment on draft-agl-cfrgcurve-00, but this
>thread is otherwise about draft-ladd-spake2 which is why I didn't
>notice it.)
>
>Yes, the use of little-endian is a deliberate decision. It reflects
>unanimous practice with the recommended curve. Also, I think there's a
>general movement towards having crypto primitives specified as
>functions on bytes strings rather than on more abstract concepts like
>points (which I support).
+1
Yes, given the diversity of uses, protocols and formats. Opaque encodings
make the most sense.
The encoding/decoding would be a method tied to the specific
algorithm/protocol/cipher suite.

Paul


>
>
>Cheers
>
>AGL
>
>-- 
>Adam Langley agl@imperialviolet.org https://www.imperialviolet.org
>
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