If you do not have a GPG key yet: gpg --full-gen-key Print your keyring: gpg --list-keys --with-keygrip Pick the keygrip of the key you want to sign with (must have flag S). Next up, sign the file: imprimatur sign ./original.pdf --keygrip <keygrip> Then, either verify the keys, or render it including signatures: imprimatur display ./original.signed.pdf imprimatur verify ./original.signed.pdf