Re: [Cfrg] Chopping out curves

Watson Ladd <watsonbladd@gmail.com> Fri, 17 January 2014 02:47 UTC

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Date: Thu, 16 Jan 2014 18:47:19 -0800
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From: Watson Ladd <watsonbladd@gmail.com>
To: Adam Back <adam@cypherspace.org>
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Cc: Trevor Perrin <trevp@trevp.net>, "cfrg@irtf.org" <cfrg@irtf.org>
Subject: Re: [Cfrg] Chopping out curves
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On Thu, Jan 16, 2014 at 6:36 PM, Adam Back <adam@cypherspace.org> wrote:
> Uh I meant the Curve25519 and Curve3617.  Sorry about that (again conflating
> safe curves and the Bernstein/Lange curves by the same authors.)

It would, but Curve25519 is a Montgomery curve and so we want an
Edwards curve for easy signatures.
T25519 should be the same curve, in a different form (if I didn't
screw up my basepoint choice, which I probably did. This weekend I
will do
a good computer search). Curve3617 has a nice Montgomery curve we
should describe for safe ECDH.

I feel like I'm coming around to Robert Ransoms arguments about how to
pick curves.
>
> Adam
>
>
> On Fri, Jan 17, 2014 at 02:14:14AM +0100, Adam Back wrote:
>>
>> Woulnt it make more sense to use two safe curve curves as they seem to be
>> what people are using and better tested/reviewed (re goldilocks).
>>
>> Adam
>>
>> On Thu, Jan 16, 2014 at 02:36:24PM -0800, Watson Ladd wrote:
>>>
>>> On Thu, Jan 16, 2014 at 2:07 PM, Dan Harkins <dharkins@lounge.org> wrote:
>>>>
>>>> On Thu, January 16, 2014 1:50 pm, Trevor Perrin wrote:
>>>>>
>>>>> On Thu, Jan 16, 2014 at 1:40 PM, Watson Ladd <watsonbladd@gmail.com>
>>>>> wrote:
>>>>>>
>>>>>> Dear all,
>>>>>> Trevor Perrin suggests that we only put in Curve25519/T25519 and
>>>>>> E383/M382 so implementors can focus on 4 curves ala Suite B. Are there
>>>>>> any protocols in which larger curves would be useful? Anything we
>>>>>> might be missing with this decision?
>>>>>
>>>>>
>>>>> I didn't quite suggest that.
>>>>>
>>>>> I do feel there should be fewer curves.  Perhaps only curve25519 and
>>>>> (either Curve3617 or Ed448-Goldilocks).
>>>>>
>



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