App\Model\Authenticator::authenticate PHP Method

    public function authenticate(array $credentials)
    {
        list($username, $password) = $credentials;
        $row = $this->database->table('users')->where('username', $username)->fetch();
        if (!$row) {
            throw new Security\AuthenticationException('The username is incorrect.', self::IDENTITY_NOT_FOUND);
        } elseif (!Security\Passwords::verify($password, $row->password)) {
            throw new Security\AuthenticationException('The password is incorrect.', self::INVALID_CREDENTIAL);
        }
        $arr = $row->toArray();
        unset($arr['password']);
        return new Security\Identity($row->id, NULL, $arr);
    }