If the authorities have a proper search warrant, I don't see why he can't be compelled to give his encryption keys. It is no different than being compelled to provide the key to a locked desk. The location of the key is irrelevant, whether it be in his mind or on his keychain.
The last of the general interest genre.
The first time I drove down Franklin Avenue in Los Angeles and saw the sign in front of their building that says "Church Of Scientology Celebrity Centre International" I was pretty sure this wasn't really a religion.