[dmarc-discuss] DKIM bit length reporting

[Zachary Harris]

* DMARC noob; excuse any naivety; did at least search the mail list
archives and site FAQ for my keywords before posting here.

  I'm currently working on getting senders with weak DKIM keys to
upgrade, and getting verifiers that "pass" DKIM that has been signed
with a weak key to be more strict. (Say you get a valid DKIM signature
based on a 384-bit public key (there are such things out there!, and
they are fun to factor on an ordinary laptop in less than 24 hours);
what rfc5451 result would you give it? "policy"? How about 512 or 768
bits?) Jim Fenton mentioned to me the idea that weak DKIM keys could be
something that verifiers report back to senders as part of DMARC
feedback. Doable?

-Zach