title: Google Plus Authentication within an Android App
body: <p>I'm trying Google Plus sign-in in an Android app (with backend support).</p>
  
  <p>I could get access token and email from the user, but know I don't know how should I recognise this user from the server. I'm sending this to the server (email and oauth token) with a POST throught SSL</p>
  
  <p>Of course I could recognise them with their email, but that would open the doors for everyone how knows another email that's on the database.</p>
  
  <p>How could I verify that the user's correctly authenticated and has sent me the correct oauth token for this email?</p>
  
  <p>Thanks!</p>