Re: [ietf-dkim] versions, Where is the formal definition of DKIM-Signature?

["Mark Delany" <[e-mail]>]

> True, but not very interesting.  In my spamassassin example, the outside 
> code knows nothing about DKIM versions, it just sees a dkim-signature 
> header and sends it to the DKIM library.
> 
> The point of a v=2 flag is to ensure that old v=1 code doesn't

As a practical matter haven't you effectively invented a new header?

After all, what are most senders going to do? They will not want their
signatures to be suddenly unrecognized by 99% of the planet so they'll continue
to generate a v=1 header and they will also want to reap the bennies of your
fantastic SpamAssassin feature so they'll additionally generate a v=2 header.

The end result is two DKIM-Signature headers with different versions for decades
to come. This will no doubt tweak some receiver is a negative way.

I think this is the biggest flaw with the whole v= rationale. There is never
going to be a v=2 change that doesn't leave everyone continuing to
generate/validate a v=1 header. Is a new header by stealth better engineering
than formalizing a new header?


Mark.
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