useridentity.php

public function authenticate()
 {
 $users=array(
     'admin'=>'admin',
 );
 if(!isset($users[$this->username]))
 	$this->errorCode=self::ERROR_USERNAME_INVALID;
 else if($users[$this->username]!==$this->password)
 	$this->errorCode=self::ERROR_PASSWORD_INVALID;
 else
 	$this->errorCode=self::ERROR_NONE;
 return !$this->errorCode;
 }
}