use Crypt::CBC;

# The Sagepay test login is at:
# https://test.sagepay.com/mysagepay 
# Login using your administrator username and password. If
# you don't know what they are contact SagePay support and
# they will send a reset link to the registered email 
# address of the administrator. After you login you 
# will see Encryption Password: <16 character long string>

my $id = <16 char long Encryption Password>; # e.g. AbcdeFghiJkLmNoP
my $iv = $id;

my $cipher = Crypt::CBC->new(
        -key         => $id,
        -iv          => $iv,
        -cipher      => 'OpenSSL::AES',
        -literal_key => 1,
        -header      => "none",
        -padding     => "standard",
        -keysize     => 16
                             );
$crypt = uc $cipher->encrypt_hex($crypt);
$crypt  = "@".$crypt;