public static function authCookie($pdo, $username, $password)
 {
     $q = $pdo->prepare('
         SELECT *
         FROM users
         WHERE username = :username
         ');
     $q->bindParam(':username', $username);
     $q->execute();
     $result = $q->fetch();
     if (hash('sha256', $result['password']) === $password) {
         $_SESSION['auth'] = $result;
     } else {
         CookieController::destroy();
     }
 }