Re: [Dcrup] I-D Action: draft-ietf-dcrup-dkim-crypto-03.txt

[Eric Rescorla <[e-mail]>]

On Sat, Jul 1, 2017 at 7:17 PM, John R Levine <[e-mail]> wrote:

> This version addresses Jim's comments, reorganizes the draft somewhat to
> put all the syntax changes in one place, and makes one significant change.
>
> SIGNIFICANT CHANGE: Only RSA signatures can use key fingerprints.  Since
> an eddsa key is 256 bits, and a SHA-256 fingerprint is also 256 bits,
> there's no point to eddsa fingerprints, so I took them out.
>
> If there is an actual problem that eddsa fingerprints would solve
> ("symmetry" isn't a problem), let me know.


Well, actually the value at hand here is consistency, not "symmetry".

In any case,  it's not true that eddsa keys are 256 bits. Eddsa keys are
256 bits when you are using X25519 but not when you are using X448. To the
extent to which you believe that it's redundant to have both non-FP and FP
variants, the answer is to *always* use a fingerprint.

-Ekr


Otherwise I'll leave them out since we now have less code to write and
> verify.
>
> R's,
> John
>
>
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