symfony not recognizing an authenticated user - authentication

Question

I am trying to implement a login page with symfony2 and for that I am using my own custom user provider.
The problem is when the user enters his credentials, he will not be recognized. By that, I mean the debug bar at the bottom says "You are not authenticated." and $request->getUser() will return null. But the strange thing is that the user will still be allowed to visit the pages that need him to log in.
I don't think the problem is with the authentication, since when I enter a wrong password, I get warned about it, but when I enter the correct one, I get redirected to the first page (but it still says "You are not authenticated.")
Do you know where I should be looking for the problem?
I have attached my security.yml file in this pastebin and routing.yml in this one.
Here is the code for my custom user provider.
And This is the User class definition.
EDIT: Here is the var_dump of my get('security.context')->getToken(). The funny thing is that authenticated is true, but getUser() is still null and the debug bar says I am not authenticated.
object(Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken)#46 (6) {
["credentials":"Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken":private]=>
NULL
["providerKey":"Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken":private]=>
string(11) "system_area"
["user":"Symfony\Component\Security\Core\Authentication\Token\AbstractToken":private]=>
NULL
["roles":"Symfony\Component\Security\Core\Authentication\Token\AbstractToken":private]=>
array(2) {
[0]=>
object(Symfony\Component\Security\Core\Role\Role)#45 (1) {
["role":"Symfony\Component\Security\Core\Role\Role":private]=>
string(10) "ROLE_ADMIN"
}
[1]=>
object(Symfony\Component\Security\Core\Role\Role)#44 (1) {
["role":"Symfony\Component\Security\Core\Role\Role":private]=>
string(9) "ROLE_USER"
}
}
["authenticated":"Symfony\Component\Security\Core\Authentication\Token\AbstractToken":private]=>
bool(true)
["attributes":"Symfony\Component\Security\Core\Authentication\Token\AbstractToken":private]=>
array(0) {
}
}

Answer 1

In order to get the current User you have to use:
$this->get('security.context')->getToken()->getUser();
In order to check if the current User has a certain role use:
$this->get('security.context')->isGranted('ROLE_USER')

Answer 2

I managed to fix the problem. It was because of the dummy code I had used in place of serialization of User objects. I replaced it with real code and problem was gone.