ietf-dkim
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Re: [ietf-dkim] Proposal: get rid of x=

2006-04-07 15:26:13
Paul Hoffman wrote:

At 1:18 PM -0700 4/7/06, Michael Thomas wrote:

Paul Hoffman wrote:

At 12:01 PM -0700 4/7/06, Michael Thomas wrote:

The alternative is to just put normative guidance in the document to the effect that x= MUST be greater than t=+2weeks, and less than t=+2 months or something,
and that it SHOULD be set to t=+4 weeks.



That is an alternative, but I would ask "why use that alternative". Unless x= is compelling, and compelling enough to overcome its faults, why even put it in with these suggested knob-settings? I claim that it is not compelling, particularly if the document says what the purpose of DKIM signatures are.



I'm confused. If we added the text you initially suggested, the result would be
that a receiver would honor the signature forever.


The receiver *could* honor the signature forever, just as they can with an x= tag. But, in doing so, they would be going against the semantics of the DKIM signature.


What semantics are those? There aren't any others in the draft that I'm aware of.
IIRC, the lack of a x= means that there is no expiration.

Are you saying now that
your original text needs to be amended to have a spec mandated lifetime?


Not at all: I'm saying my original text needs to be amended to add the WG's intention of what DKIM signatures are for. (I thought it was already there but, after reading the thread and then going back to the document, couldn't find it. It must be ingrained in our beliefs, but not in our text.)


It's not there because with x= it's configurable by the signer.


Assuming your answer is "yes" above, then that's really what's at issue right?


Correct assumption, but incorrect conclusion. What's "really" at issue is whether to have a unneeded tag that can cause problems when removing the tag (and replacing it with text about what the protocol is for) is better.


I'm sorry, just saying that the protocol is for "transport time" is not going to help developers, and is likely to lead to the inconsistencies and incompatibility that you are trying to get rid of. x= leaves it as a decision of the signer to determine what it wants. Letting a receiver just pick a number out of thin air is definitely not what we want -- especially when some dumb receivers would find it oh-so-suspicious that mail didn't get to them in the normal 20 minutes and declare the signature
dead.

But I'm still confused: are you saying that your original proposal needs work, or
that it's still what you want?

      Mike
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