title: Keeping users uploaded documents private
body: <p>I believe this question is platform/technology independent, however I am using Ruby on Rails with the carrierwave gem.</p>
  
  <p>Users upload documents to my site, and I need to keep them private. I am exploring the different options available to me, along with their advantages and disadvantages.</p>
  
  <p>Option 1</p>
  
  <p>Obfuscate urls to images to make them impossible to guess.</p>
  
  <p>This would be relatively simple to implement and fast to serve up. However, if a url was made public by whatever means, security is lost.</p>
  
  <p>Option 2</p>
  
  <p>Have documents accessed through some sort of intermediate step that requires authentication. This would have improved security over option 1, but would place additional load on the server. A page containing previews of a number of uploaded documents would hammer the server.</p>
  
  <p>Are there any other options available to me? Have I made any mistakes with my claims, or missed any important points? </p>