Criptografia para PHP 5.3

criptografia.php

<?

function encrypt($string, $key) {
        $encryptionMethod = "AES-256-CBC";
        $ivkey = sha1($key);
        $iv = substr($ivkey, 0, 16);

        return base64_encode(openssl_encrypt($string, $encryptionMethod, $key, 0, $iv));
}


function decrypt($string, $key) {
        $string = base64_decode($string);
        $encryptionMethod = "AES-256-CBC";

        $ivkey = sha1($key);
        $iv = substr($ivkey, 0, 16);

        return openssl_decrypt($string, $encryptionMethod, $key, 0, $iv);
}

?>