This package (and corresponding support in app-crypt/pinentry)
provides a way to input a passphrase through the Emacs minibuffer.

To use it, add the line

    allow-emacs-pinentry

to your gpg-agent.conf configuration file, which can usually be found
in the ~/.gnupg/ directory.

The pinentry server can be started with the command "pinentry-start".
You may add the following line to your Emacs configuration file:

    (pinentry-start 'quiet)