Enable pinentry mode ‘loopback’ on GnuPG 2.1.11

Add this line to ~/.gnupg/gpg-agent.conf:

allow-loopback-pinentry

Then restart gpg-agent:

$ gpgconf --reload gpg-agent

That’s all 🙌

Fluidkeys uses loopback mode to maintain keys automatically

Loopback mode allows Fluidkeys to send a password directly to GnuPG, rather than GnuPG itself prompting for the password.

This lets Fluidkeys store the password in the system keyring, then run automatic maintenance from cron (see fk key maintain automatic)

Unfortunately GnuPG 2.1.11 throws an error if you try to use loopback mode:

gpg: setting pinentry mode 'loopback' failed: Not supported

This was fixed in GnuPG 2.1.12, but if you’re using Ubuntu 16.04 you’re stuck with the affected version.