title: ios client <> php backend encryption
body: <p>This may be somewhat of a faugue description of my question, and I am unsure if this is best to be posted on Stackoverflow or on Super User.</p>
  
  <p>My problem is the following, I am in planning stage of building an quiz ios-app. In some cases it would actually hand out physical prizes monthly, which means security must be tight enough to decrease cheating possibilities.
  I will build a backend in PHP, on a debian server with Apache and a certified SSL (Rapid-SSL). </p>
  
  <p>My guess is that for every question, it needs to send it back and forth to the server for the server to authenticate the answer, and let the user know if the answer was correct or not. For some cases (the non-price-winning quizzes) I even want to return the correct answer. </p>
  
  <p>My question is, what is the best way of doing this, security wise? Should I encode the data that is being send back and forth, and if so... how and with what (is there some common encoding type which I can use, such as base64 or similar)?</p>
  
  <p><em><strong>Edit</em></strong><br/>
  What I meant was encoding, rather then encryption. I updated the question</p>
  
  <p>Also, for authentication I was thinking of using Facebook OAuth login.</p>