title: how to implement backend server authentication with google play games services for android
body: <p>Maybe I overlooked something, but through Play Games Services documentation <a href="https://developers.google.com/games/services/android/quickstart" rel="nofollow">https://developers.google.com/games/services/android/quickstart</a>,I did not yet get any idea about how to implement backend server authentication like how to get a token from Google's server and pass it to my own backend server to verify a login.  I wish someone can give me a clue. Thanks !</p>