title: Authentication using Glass
body: <p>We have an existing Android and iOS application that consumes REST API from our servers. The API provides a token to the authenticated users after they log in using their credentials (username, password combo.) from the mobile applications.</p>
  
  <p>Now, we're planning to create a Google Glass application for the same. In this case, we'd like to use the existing REST API along with Glass also. The Glass app will be built natively using the GDK.</p>
  
  <p>My concern is, how would the users be able to input credentials? Because, users may have signed up for the service using non-google accounts?</p>
  
  <p>Many thanks in advance.</p>