Paypal säkerhet, php till asp? Kryptering?

Finally I got the solution for this.Contruct the Paypal URL and simply header the user to that URL. Paypal will direct the user to the appropriate session.

 $params = array(
                    'cmd'                    =>      '_xclick',
                    'business'            =>      'sell_1284352423_biz@gmail.com',
                    'item_name'         =>      'Item One',
                    'return'                 =>      'http://www.yoursite.com/paypalreturn',
                    'paymentType'     =>      'Sale',
                    'invoice'                =>      '390218',
                    'amount'               =>      '17.50',
                    'currency_code'   =>      'USD'
                );
   
            $api_url = 'https://www.sandbox.paypal.com/cgi-bin/webscr?';
   
            // Construct the URL
            foreach ($params as $key => $value )
            {
                $api_url .= $key . '=' . urlencode($value) . '&';
            }
   
            $result = file_get_contents($api_url);  // You can use curl instead of this

 

            // direct the user to the paypal
            header('Location:'.$api_url);

 No HTML forms or hidden fields. So no more firebuggers can change the cart values.