<?php
$data = "Test Data\x00\x00";
echo strlen($data)."\n";

$key = "mykey";
$blocksize = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_ECB);

// PKCS7 Padding
$pad = $blocksize - (strlen($data) % $blocksize);
$data .= str_repeat(chr($pad), $pad);

$encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, MD5($key, true), $data, MCRYPT_MODE_ECB);
echo strlen($encrypted)."\n";

$decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, MD5($key, true), $encrypted, MCRYPT_MODE_ECB);
echo strlen($decrypted)."\n";

// PKCS7 Padding
$strPad = ord($decrypted[strlen($decrypted)-1]);
$newData = substr($decrypted, 0, -$strPad);

echo strlen($newData)."\n";