title: Rails Secure Download
body: <p>I am building an rails app and I want to secure the user's downloads.</p>
  
  <p>The scenario is:
  There is an item with a download column of "/some_directories/some_file.zip".</p>
  
  <p>A user buys the file, goes to "My downloads" page and clicks "Download". The download button is checking if the user really bought the file, and if he did it is sending the data of the download column of the item. All is good. Now, the user will see where the download came from (example.com/some_directories/some_file.zip) and just send the URL to his friends. My question is, how can I prevent this situation? How can I let only the customers of the item download this file, no matter what?</p>
  
  <p>Thank you very much</p>
  
  <p>Adam</p>