Subject: RE: [ietf-dkim] Supporting alternate algorithms

From: "Hallam-Baker, Phillip" <[email-masked]>
Date: Tue, 21 Feb 2006 18:21:08 -0800

> [mailto:[email-masked]] On Behalf Of Dave Crocker

> I don't think I understand what it means for a signer to be 
> required to support two different "SHOULD" requirements for 
> the same function.
> 
> Hmmm.
> 
> Perhaps there is a distinction between saying that the 
> signing implementation MUST *support* a core set of 
> algorithms, versus that a signer SHOULD *use* one of them?

We could go with signers SHOULD support at least one of SHA-1 and
SHA-256.

It could be argued this needs to be a MUST but I am nervous about
mandating support for an alg we know is likely to be deprecated before
the spec is reved.

For interop we need to make verifier support a MUST.

I would like to know more about the precise patent encumberances of ECC.
I can well imagine that when the time comes to upgrade alg requirements
we mandate ECC support. DKIM is a classic application for ECC.

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