how do i use cookie

[ALIXLUBIN]

Hi, I'm trying to use cookies to authenticate users. I'm only stuck on the controller. How am I supposed to retrieve information from the cookie?

$oauth = new Oauth();
$request = Request::createFromGlobals();
$response = new Response();

if(!$oauth->server->verifyResourceRequest($request)){
 $oauth->server->getResponse()->send();
 die('no');
}