/**
* Creates the HMAC for the cookie.
*
* The HMAC is used to ensure the cookie cannot be tampered or replayed.
*
* @param string $userGID the user GID
* @param string $data the serialized data
* @param int $expires the expiration date
* @param string $key the key generated by <code>createKey()</code>
* @return string the HMAC
*/
private function createHMAC($userGID, $data, $expires, $key)
{
return $this->hmacFunction->calculateHMAC($userGID . $expires . $data . $this->sessionIdentifier, $key);
}
