The script delegates to the GPG binaries where necessary. From the 'Using...' section: "There will be a nice password input dialog using the standard gpg-agent

The script delegates to the GPG binaries where necessary. From the 'Using...' section: "There will be a nice password input dialog using the standard gpg-agent (which can be configured to stay authenticated for several minutes), since all passwords are encrypted." When setting up the pass store, you also specify the identity of a GPG key to use (or set of keys which may be used).