Install libpgp-sign-perl by entering the following commands in the terminal:
sudo apt update sudo apt install libpgp-sign-perl
Perl module to create detached PGP signatures
PGP::Sign creates and checks detached PGP signatures for textual data using GnuPG. Other PGP implementations are also supported with run-time configuration. Secret key passphrases are passed via a pipe, and no temporary files are required for signature generation (but are for signature verification).