gpg

Links

- <https://www.gnupg.org/documentation/howtos.html>
- <http://zacharyvoase.com/2009/08/20/openpgp/>
- <https://help.riseup.net/en/security/message-security/openpgp/best-practices>
- <https://gist.github.com/grugq/03167bed45e774551155>