Just want to throw this out there: could you make do just calling gpg with system calls or using IPC::Open3? For basic operation (encrypting, decrypting, signing messages), I think this would be enough.

For example:

use strict;
use warnings;

my $file = 'test.txt';
my $recipient = 'joe@example.com';
my ($armor) = (0);      # 1 to generate ascii, 0 to work with binary

system('gpg',
       $armor ? qw(--armor) : (),
       '--recipient' => $recipient,
       '--encrypt'   => $file) and die "Exit code: $?";

system('gpg',
       '--output'  => "${file}_decrypted",
       '--decrypt' => $file . ($armor ? ".asc" : ".gpg"))
    and die "Exit code: $?";

system('gpg',
       $armor ? qw(--armor) : (),
       "--output"      => "${file}.sig",
       '--detach-sign' => $file) and die "Exit code: $?";
[download]

Some of the key management could be a little too involved for this method, but depending on what you're trying to do, and seeing that there's not much out there on CPAN, maybe a simpler approach is warranted?