I tried something different. If you have OpenSSL, then try Crypt::OpenSSL::AES. Here's my resulting script:

#!/usr/local/bin/perl

use strict;
use warnings;
use Crypt::CBC;

my $key = 'little brown mouse';
my $cipher = Crypt::CBC->new(
    -key       => $key,
    -keylength => '256',
    -cipher    => "Crypt::OpenSSL::AES"
);             

my $encrypted = $cipher->encrypt_hex($key);
my $decrypted = $cipher->decrypt_hex($encrypted);

print $encrypted, "\n";
print $decrypted, "\n";
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