function make_hash() {
    $rand = dede_random_bytes(16);
    $_SESSION['token'] = ($rand === FALSE) ? md5(uniqid(mt_rand(), TRUE)) : bin2hex($rand);
    return $_SESSION['token'];
}

function dede_random_bytes($length) {
    if (empty($length) OR !ctype_digit((string) $length)) {
        return FALSE;
    }
    if (function_exists('random_bytes')) {
        try {
            return random_bytes((int) $length);
        } catch (Exception $e) {
            return FALSE;
        }
    }
    if (defined('MCRYPT_DEV_URANDOM') && ($output = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)) !== FALSE) {
        return $output;
    }
    if (is_readable('/dev/urandom') && ($fp = fopen('/dev/urandom', 'rb')) !== FALSE) {
        is_php('5.4') && stream_set_chunk_size($fp, $length);
        $output = fread($fp, $length);
        fclose($fp);
        if ($output !== FALSE) {
            return $output;
        }
    }
    if (function_exists('openssl_random_pseudo_bytes')) {
        return openssl_random_pseudo_bytes($length);
    }
    return FALSE;
}