Subject: [Cfrg] Rationale for relative size of ECC primes/keys vs symmetric keys

From: Tony Arcieri <[email-masked]>
Date: Thu, 12 Feb 2015 23:49:19 -0800

I was looking through draft-irtf-cfrg-curves-01 for a justification or
framework for how the sizes of ECC keys (and their nearest primes) map to
symmetric security levels.

These sizes seem incredibly important to the current discussion about
high-security curves, yet if there's a specific methodology described for
relating ECC key sizes to relative symmetric key sizes described
in draft-irtf-cfrg-curves-01, I can't find it, and if it's not there,
perhaps it should be?

-- 
Tony Arcieri

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From: "Paterson, Kenny" <[email-masked]>
Date: Fri, 13 Feb 2015 10:31:29 +0000

Hi Tony,

On 13/02/2015 07:49, "Tony Arcieri" <[email-masked]> wrote:

>relating ECC key sizes to relative symmetric key sizes described in
>draft-irtf-cfrg-curves-01, I can't find
> it, and if it's not there, perhaps it should be?
>

That's a good idea. The equivalences are fairly well described in, for
example, Section 6 of the ECRYPT-II annual report on algorithms and key
sizes: 

http://www.ecrypt.eu.org/documents/D.SPA.20.pdf

and subsequent ENISA reports:

http://www.enisa.europa.eu/activities/identity-and-trust/library/deliverabl
es/algorithms-key-sizes-and-parameters-report

There are also NIST documents which do much the same thing, referred to in
the above reports.

Editors of draft-irtf-cfrg-curves (in cc): please could you make a note to
include some rationale in the next version? This may only need to point to
sources like those above.

Cheers,

Kenny

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From: Aaron Zauner <[email-masked]>
Date: Fri, 13 Feb 2015 14:12:39 +0100

Hi,

You all probably already know these references (and the website) but
just for the record http://www.keylength.com/

Aaron