[drupal-support] Download only for Authenticated users

[Cláudio]

Hi, list.

I want to implement this feature in a site (some files only available to 
authenticated users), already saw how to protect a page 
(node_privacy_byrole module), and how to upload files (attachment module).
I already saw a discussion of the exact same problem  (in 
http://drupal.org/node/23882), but my concern is that uploaded files are 
visible to anyone who knows the exact URL of the uploaded files (at 
least when I implemented it).
Anyone can give me a direction to follow, even if a have to learn a bit 
of php?

Cláudio