Remote URL : security problems

Remote URL : security problems

Hello,
may be i'm not the first to ask some help about the remote url, but i didn't find my answer yet.

So, to work with the remote api, we must construct a form. You specify in the doc for the variable "url" :
"it is mandatory to specify the absolute path of the document in url parameter with proper file extension."

So everything work perfectly when i use an url like :
http://mydomain/sites/onesites/media/files/graph.xls
where the url contains the absolute path to the file.

But in this situation my file are accessible over the web, and for public. So i prefer to specify an url to zoho like :
http://mydomain/protected/services.php?ticket=dc0f81052e1b6df8f884a0417d8d0352
Where i use a system of ticket to authorise access on file, and the file are not public.

How can i deal with my security of my file ? and my communication with zoho ?

thx