How to pass parameters to other pages in VK Iframe application?

Question

In contact with

I found it with difficulty (empirically) in the iframe application in the VK get'om a bunch of parameters are passed

Array
(
    [api_url] => http://api.vk.com/api.php
    [api_id] => 4123456
    [api_settings] => 1
     [viewer_id] => 1
   ...
)

But they are only passed to the index page.
The question is how do I pass them to other iframe pages?
On the forums, they write in the link add &viewer_id=1 , but this is nonsense, so anyone can change them.
There is an option to encrypt, but maybe there are better options?