----- Original Message -----
From: "Mark Delany" <MarkD+dkim(_at_)yahoo-inc(_dot_)com>
To: <ietf-dkim(_at_)mipassoc(_dot_)org>
Sent: Tuesday, April 11, 2006 11:45 PM
Subject: [ietf-dkim] Re: Straw poll on x=
Remove x=
The tagging mechanism makes it trivial to add new tags. If at some
point in the future, x= is given a precise and purposeful rationale,
that can easily be done as an extension to the base.
IMO, there is a precise and purposeful rationale. I can come up with
atleast a dozen reasons or more why a signer may want to utilize an
expiration concept.
But there all for under a single rationale:
The signer wants the verifier to classify the message as "invalid" at this
time and date. Its should not be the verifier's concern why the signer
wants expire a signing. It might not even apply to all outgoing mail. It
might just be set for certain kinds of high-value transactions. The
possibilities are end-less.
Also consider, per spec, If the signer doesn't want to define one, he
doesn't have to. This is the default condition.
However, I agree what isn't precise is the mechanics. What isn't resolved
is the design question:
a) It is a transaction expiration concept, or
b) Message Validity expiration concept?
And this touches base with a more general implementation conflict regarding
dynamic transport verification mode vs. post transport delay verification
mode.
This is fixable with the proposed change to the x= mechanics.
---
Hector
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