ietf-dkim
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Re: [ietf-dkim] double header reality check

2010-10-20 04:47:51
At 17:53 19-10-10, Mark Delany wrote:
In a DKIM world a list server could reasonable use DKIM to bypass this
"confirm" sequence and make your life a bit simpler. Perhaps it relies
on Authentication-Results or somesuch. In any event such a list server
is actually *more* vulnerable than it is today if we let thru bogus
payload that appear to be valid.

According to Section 7 of RFC 5672:

   "For DKIM processing, the domain name portion of the AUID has
    only basic domain name semantics; any possible owner-specific
    semantics are outside the scope of DKIM."

Furthermore, in Section 8:

   "A module that consumes DKIM's mandatory payload, which is the
    responsible Signing Domain Identifier (SDID).  The module is
    dedicated to the assessment of the delivered identifier.  Other
    DKIM (and non-DKIM) values can also be delivered to this module as
    well as to a more general message evaluation filtering engine.
    However, this additional activity is outside the scope of the DKIM
    signature specification."

Based on the above, I don't think that a list server could use DKIM 
to bypass the "confirm" sequence.

Regards,
-sm 

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