title: Best way to set file-download permissions on Rails 3
body: <p>I want to secure some files that are on my site, but also I want to give permissions to some users to download that files. What is the best way to do it? </p>
  
  <p>I have only one idea - generate temporary random URL's like <code>/files/hdad8fda299asnfqe/foo.bar</code></p>
  
  <p>But I hardly want that other users can not use others URLs.</p>
  
  <p>Do you know any gem that can help me or suggest another way to secure files?</p>