On 12/9/22 3:29 PM, Grant Taylor wrote:
On 12/9/22 10:36 AM, Michael Thomas wrote:
One of the original goals was that the sending domain could
theoretically take responsibility for sending the mail. It was never
defined what that might entail but since a protocol was never
envisioned for this to happen in transit, it was tacitly assumed that
it was some out of band mechanism, like oh say, sending mail to
abuse@ or something like that. They could then see that it was really
from them and take action on the user who sent it. That's especially
true when submission became the norm.
If the signature was stripped out of the mail, it gives an easy out
for the sending domain to disclaim its involvement. That defeats the
entire utility of taking responsibility. That's a problem, and we
shouldn't be stripping out perfectly valid functionality.
This seems very reminiscent of the non-repudiation that S/MIME / PGP
signatures provide. With the difference being that S/MIME / PGP
signatures operate with user granularity, while DKIM operates with
host (or domain if keys are shared among hosts) granularity.
Is that an accurate take away from your statements Mike?
I'm not sure I understand the exact technical definition of
non-repudiation so I'll not go out on a limb, but i'm saying that some
use cases require that the signature survive for at least some amount of
time. How much time is a good question. But frankly this has always been
under the control of the sender since it can always unpublish the
selector key.
As for this talk about removing the signature at the MDA for "replay
protection", what makes people think they can't find MDA's that don't (=
all now) or can't set one up?
Mike
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