[ietf-dkim] Deployment Scenario 7: Cryptographic Upgrade and Downgrade Attacks

[Arvel Hathcock]

Mike, this is what I was trying to say in a previous post.  You are 
exactly right.  We have already faced this situation and it has proven 
itself in the field to work just fine.

Arvel

Michael Thomas wrote:
> I'm still not seeing what the problem is with things as they stand now.
> We've already been through a transition with sha1 and sha256. The
> solution was to make both signatures in the transition and set the
> h=sha1|sha256; in the selector. All you do when you're ready to
> completely transition is only sign with the new algorithm and set
> h=sha256; in the selector. This is exactly the kind of case we wanted
> to get right for -base and as far as I can tell it worked exactly as
> intended.
> 
> I'm honestly not trying to be obtuse here.