Hi,
At the IETF 94 OpenPGP WG session, Bryan, if I recall correctly,
suggested that we should try and hide more meta-data. For instance,
instead of listing the recipients, someone decrypting a message would
try each of their available secret keys in turn. Werner pointed out
that these probes are a pain for people who use a passphrase protected
key and I mentioned that it is a pain for people who use a smartcard,
in paritcular, those who use more than one smartcard.
What about using a bloom filter for encoding the recipients? This, of
course, doesn't eliminate the meta-data leak and it can lead to false
positives (= gratuitious passphrase prompts / smartcard prompts), but
it should reduce the metadata leak a fair amount, I think. Thoughts?
Thanks,
:) Neal
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