OOP Problems

In mosapi.php :

require_once('database.php');
require_once('util.class.php');
require_once('auth.class.php');

$db     = new Database();
$util   = new Util();
$auth   = new Auth($db,$util);

    if(isset($_POST['type']) && !empty($_POST['type']))
    {
        switch($_POST['type'])
        {
            case 'reqchklogin':
            $auth->reqchklogin($_POST['mail'],$_POST['pass']);
            break;

            default :
            break;
        }
    }
    else
    {
        badrequestpage();
    }
-------------------------------------------------------------------------------------------------------------------------------------

In auth.class.php :
--------------------------------------------------------------------------------------------------------------------------------------
class Auth
{
    private $db;
    private $util;

    public function __contruct($db,$util)
    {
        $this->db   = $db;
        $this->util = $util;
    }

    public function reqchklogin($email,$password)
    {
        $email      = htmlentities(addslashes($email));
        $password = htmlentities(addslashes($password));

        //$dataRespons = [];
        $dataRespons = null;
        $pass = $this->util->encode($password);     /* <----- problem here  */

        $query      = "SELECT * FROM tbl_user WHERE username=? AND password=? ";
        $chk_data   = $this->db->getValue($query,[$email,$pass]);
        ....
    }
}
---------------------------------------------------------------------------------------------------------------------------------------
In util.class.php :
class Util
{
    ...
    public function encode($word)
    {
        if(!$word)
        {
            return false;
        }

        $text       = $word;
        $iv_size    = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
        $iv         = mcrypt_create_iv($iv_size, MCRYPT_RAND);
        $crypttext= mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $this->skey, $text, MCRYPT_MODE_ECB, $iv);
        return trim($this->safe_b64encode($crypttext));
    }
    ....
}