An example security.php script.

<?php

switch ($_POST['form'])
{
    case 'login':
        $allowed = array();
        $allowed[] = 'form';
        $allowed[] = 'username';
        $allowed[] = 'password';

        $sent = array_keys($_POST);

        if ($allowed == $sent)
        {
            include '/inc/logic/process.inc';
        }

        break;
}

?>