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Re: [Cfrg] Elliptic Curves - poll on security levels (ends on February 17th)

Phillip Hallam-Baker <phill@hallambaker.com> Tue, 10 February 2015 16:28 UTC

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Date: Tue, 10 Feb 2015 11:28:24 -0500
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From: Phillip Hallam-Baker <phill@hallambaker.com>
To: Christoph Anton Mitterer <calestyo@scientia.net>
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Subject: Re: [Cfrg] Elliptic Curves - poll on security levels (ends on February 17th)
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On Tue, Feb 10, 2015 at 10:19 AM, Christoph Anton Mitterer <
calestyo@scientia.net> wrote:

> On Tue, 2015-02-10 at 10:52 +0000, Alexey Melnikov wrote:
> > Q1: Should CFRG recommend a curve at the 192-bit security level?
> Optionally, but the focus should be on 256bit, or higher
>
> > Q2: Should CFRG recommend a curve at the 256-bit security level?
> Yes.
>
>
> None of this should mean however, that efforts for the much higher
> security levels >=512 respectively 521 bits would be abandoned.
>
> It appears the poll is causing confusion. Curve 25519 is a 255 bit prime
that is being positioned to deliver a 128 bit security level.

In practice it is rather more, but the 'naive' approach to ECC strength is
to halve the bit size.

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