Duo\Web::parseVals PHP Метод

    private static function parseVals($key, $val, $prefix, $ikey, $time = null)
    {
        $ts = $time ? $time : time();
        $parts = explode('|', $val);
        if (count($parts) !== 3) {
            return null;
        }
        list($u_prefix, $u_b64, $u_sig) = $parts;
        $sig = hash_hmac("sha1", $u_prefix . '|' . $u_b64, $key);
        if (hash_hmac("sha1", $sig, $key) !== hash_hmac("sha1", $u_sig, $key)) {
            return null;
        }
        if ($u_prefix !== $prefix) {
            return null;
        }
        $cookie_parts = explode('|', base64_decode($u_b64));
        if (count($cookie_parts) !== 3) {
            return null;
        }
        list($user, $u_ikey, $exp) = $cookie_parts;
        if ($u_ikey !== $ikey) {
            return null;
        }
        if ($ts >= intval($exp)) {
            return null;
        }
        return $user;
    }