Using gnupg as a proxy for password challenge with rnpgp

[shemeshg]

I have an idea for a simpler way to use security cards like YubiKey with rnpgp.

Basically, the .rnp security key would say “the password is a proxy to challenge against the gnupg executable” and let gnupg handle the rest.

Instead of trying to implement security card directly into rnpgp, we can store the keys in the .rnp folder and use gnupg to authenticate them. This can be done by using a simple process that does not rely on gpgme thread, so it will also work on Windows 64x.

This way, we can leverage the strengths of both gnupg and rnpgp: gnupg for authentication and rnpgp for fast multithreading multiprocess encryption.