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Re: [ietf-dkim] ISSUE 1525 -- Restriction to posting by first Author breaks email semantics

2008-01-15 10:59:03

On Jan 15, 2008, at 4:01 AM, Charles Lindsey wrote:

On Mon, 14 Jan 2008 17:33:37 -0000, Dave Crocker <dhc(_at_)dcrocker(_dot_)net> wrote:

Your reading of the archive shows rather more complete and definitive discussion than mine. In fact I read the archive as tending in the direction of changing the specification to use Sender: rather than From.

Would you please explain the basis for assessing that this topic got sufficient discussion and that there was rough consensus on it?

Since this specification modifies RFC2822 that fact needs explicit justification.

The current SSP language modifies RFC2822, and so there should be considerable clarity about the need, the benefit, and the impact.

Indeed. I don't like that "1st author" bit.

At least this limits the expected number of transactions for obtaining the SSP policy. : )

If there are multiple authors, then whichever one is also the Sender should be the one that the signature should relate to.

Agreed. The signature should accurately reflect which entity the signature is on-behalf-of.

If the Sender is none of them (the secretary sent it on behalf of them all), then there is a problem. In that case I might be happy for the Sender to match the signature, or even to go back to a "first author", though I don't really see what is wrong with an "at least one author".

There is not a problem when signatures are permitted to be on-behalf- of any header or entity with a proviso that the signature's domain would have been valid when used for the "first author". The only case where this might be a problem would be when g= restricted keys are used to sign on-behalf-of entities that are not "first authors". The easiest solution would be to declare signatures not on-behalf-of "first authors" having restricted keys to be considered "invalid" for the purpose of SSP compliance evaluation.

It the Sender is absent with multiple authors, then the message if not RFC 2822 compliant, and all bets are off.

Dave was right to suggest only considering the domain of the signature. This problem is greatly simplified by only considering the domain of the signature to be significant.

And if the signature is "restricted" (by g= or whatever), then the rules might be different.

Agreed. A restricted key is the _only_ case where a domain's signing policy might not have permitted restricted key's use for entities that are not "first authors".

-Doug

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