GNU Privacy Guard 2. More information: https://docs.releng.linuxfoundation.org/en/latest/gpg.html.
gpg2 --list-keys
.gpg
appended:gpg2 --encrypt --recipient {{alice@example.com}} {{path/to/doc.txt}}
.gpg
appended:gpg2 --symmetric {{path/to/doc.txt}}
gpg2 --decrypt {{path/to/doc.txt.gpg}}
gpg2 --import {{path/to/public_key.gpg}}
gpg2 --export --armor {{alice@example.com}}
gpg2 --export-secret-keys --armor {{alice@example.com}}