Same return value in php and perl 3DES CBC

I would like to know how to return the same values for a 3DES encription in perl and php. The PHP code is the following:

$bytes = array(0,0,0,0,0,0,0,0);
$iv = implode(array_map("chr", $bytes)); 
$ciphertext = mcrypt_encrypt(MCRYPT_3DES, base64_decode('Mk9m98IfEblmPfrpsawt7BmxObt98Jev'), '0000001920', MCRYPT_MODE_CBC, $iv);
echo base64_encode($ciphertext);

The result is: "A/VCTXA6q/x/emW0zzlSDg=="

The perl code is:

use Crypt::CBC;
$cipher = Crypt::CBC->new(  -key    => decode_base64('Mk9m98IfEblmPfrpsawt7BmxObt98Jev'),
                                -cipher => 'DES_EDE3',
                                -iv     => pack("H*","0000000000000000"),
                                -literal_key => 1,
                                -header      => 'none'
                            );

$ciphertext = $cipher->encrypt("0000001920");
print encode_base64($ciphertext, '');

The result is: "A/VCTXA6q/y9g7ypgqlWIg=="

The results are very similar, what I'm doing wrong in my perl code?

Solution

You are not using the same padding mechanism.

If you read the reference page of PHP's mcrypt_encrypt very carefully you'll see the following note next to the data parameter:

If the size of the data is not n * blocksize, the data will be padded with '\0'.

Now, if you also read the reference page of Perls Crypt::CBC, you notice they have several padding methods (defined by the -padding parameter). The default is PKCS#5 which is something different than just padding with 0x00.

Now if you change the padding to "null", Perl prints the same as PHP. So your code should look like this:

use MIME::Base64;
use Crypt::CBC;
$cipher = Crypt::CBC->new(  -key    => decode_base64('Mk9m98IfEblmPfrpsawt7BmxObt98Jev'),
                                -cipher => 'DES_EDE3',
                                -iv     => pack("H*","0000000000000000"),
                                -padding     => "null",
                                -literal_key => 1,
                                -header      => 'none'
                            );

$ciphertext = $cipher->encrypt("0000001920");
print encode_base64($ciphertext, '');

Alternatively you could implement PKCS#5 in PHP, which you have to do by yourself, since PHP does not include it by default (search for PHP PKCS#5 and you probably find some code-snippets which you can use, theres even a simple PKCS#5 function in one of the PHP-doc comments).