ietf-dkim
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Re: [ietf-dkim] Alternative to SSP

2006-03-27 10:03:17

On Mar 26, 2006, at 7:45 PM, Tony Hansen wrote:

One message that I wrote had a table, showing what a couple possible
syntaxes might be for o=

                o=-signature,-3ps       signature=never,3ps=never
?/WEAK          o=~signature,-3ps       signature=optional,3ps=never
~/NEUTRAL       o=~signature,+3ps       signature=optional,3ps=allowed
!/EXCLUSIVE     o=+signature,-3ps       signature=always,3ps=never
-/STRONG        o=+signature,+3ps       signature=always,3ps=allowed
./NEVER         o=nomail                nomail
^/USER          o=user                  checkuser


These tokens are related to use of a From email-address with a DKIM signature of the same domain. Signature being optional while disallowing third-party signatures makes little sense. The user level mode takes a high level of DNS transactions to a higher level while also exposing email-addresses. If the mode restricts the use of From email-address to that of a DKIM signature of the same domain, there should be no need to indicate that no mail is sent.

With the use of specialized labels "*." for "open-ended" and "." for "only this domain" would allow the following meanings:

First-party signatures should include these domains and others.

_fps._dkim.<from-domain>. PTR this-domain.tld.
                          PTR that-domain.tld.
                          PTR *.


First-party signatures should only include this domain.

_fps._dkim.<from-domain>. PTR .



Key Group Tags provides a lower cost solution than a user level approach, and where annotation conventions could better protect recipients.

A PTR and Key Group Tag would allow for all these modes and yet provide better information.

-Doug





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