GNU Privacy Guard. More information: https://gnupg.org.
gpg --clearsign {{doc.txt}}
gpg --encrypt --recipient {{alice@example.com}} {{doc.txt}}
gpg --symmetric {{doc.txt}}
stdout
):gpg --decrypt {{doc.txt.gpg}}
gpg --import {{public.gpg}}
stdout
):gpg --export --armor {{alice@example.com}}
stdout
):gpg --export-secret-keys --armor {{alice@example.com}}