auth-source backend stuff

[Eric Abrahamsen <eric@ericabrahamsen.net>]

I see that auth-source.el is written to provide backend subclassing, but
I've found the system as a whole a bit confusing to grasp. I've got a
couple of questions I'm hoping someone can provide pointers for.

1. I keep my email passwords in the unix "pass" utility, which I'm very
   pleased with. I've been able to get pretty much all my other programs
   (msmtp, mbsync) to draw passwords from that, with the exception of
   Gnus. Has anyone tackled a "pass"-specific auth backend?
2. Failing that, how hard would it be to make the ~/.authinfo system
   smarter about PGP encryption? I have a ~/.authinfo.gpg file, but no
   ~/.authinfo. If I add a new backend, I'm first prompted to add the
   login details to ~/.authinfo, after which I have to manually copy
   them into the encrypted version of the file, then delete the
   unencrypted version. Could Gnus check for the presence of an
   ~/.authinfo.gpg file, and handle that gracefully?

Thanks,
Eric