PHP_MCRYPT_CBC_256

encryption.php

<?php

/**
 * Used to encrypt data for Web Transport.
 *
 * Code from the link attached and modified to be better.
 * @link http://truelogic.org/wordpress/2012/09/14/url-masking-by-encrypting-query-string/
 * @param Array  Data to Encrypt and Return
 * @param String Encryption Key used to make the Output
 */
function encryptData($data, $keySalt = null){
    if($keySalt == null){ return false; }
    $qryStr = json_encode($data);  //making query string
    $query = base64_encode(
        mcrypt_encrypt(
            MCRYPT_RIJNDAEL_256,
            md5($keySalt), $qryStr,
            MCRYPT_MODE_CBC, md5(md5($keySalt))
        )
    );
    return $query;
}

/**
 * Used to decrypt data the has been encrypted via encryptData.
 *
 * Code from the link attached and modified to be better.
 * @link http://truelogic.org/wordpress/2012/09/14/url-masking-by-encrypting-query-string/
 * @param String The Data that is Encrypted by encryptData
 * @param String Encryption Key used to make the encrypted data.
 */
function decryptData($data, $keySalt){
    if($keySalt == null){ return false; }
    $queryString = rtrim(
        mcrypt_decrypt(
            MCRYPT_RIJNDAEL_256, md5($keySalt),
            base64_decode($data),
            MCRYPT_MODE_CBC, md5(md5($keySalt))
        )
     , "\0");
    return json_decode($queryString, true);
}

// Test Code
$t = encryptData($_SERVER, "KEY_GOES_HERE");
echo "Out Data:<br>";
echo $t;
echo "<br><br>In Data:<br>";

print_r( decryptData($t, "KEY_GOES_HERE") );

?>