[Dcrup] hashing and privacy

[Brandon Long <[e-mail]>]

There has been a concern that long term DKIM keys allow for some type of
possibly privacy violation by allowing leaked data to be verified.

I'm not sure I share this concern, but if take it as a given, then the
following occurs to me for the new proposed hashing schemes.

The schemes propose that the key be always included, and the hash of they
key be available in DNS.

On rotation, the hash will be gone... but, one would be able to verify that
the key was the "right" key by looking at any other mail from the same
system at the same time.

Now, it's possible that people are already logging DKIM keys in DNS for
long term retrieval for the next one of these leaks, in which case, that
cat is already out of the bag anyways.

Brandon