title: Securing REST calls made by JavaScript from an unsecured page
body: <p>We have a web-based application in which we are not requiring end users to login. The application uses Ajax to make calls to REST services hosted on the same server. Besides this application, we want to make sure that if any other applications / agents call the REST service they get denied. </p>
  
  <p>What is the simplest way to secure a REST API like this? My guess is that we would include some sort of security token and make the call through HTTPS. However I'm not clear how the Ajax application would create/obtain/encrypt the token and generally what the lifecycle looks like.</p>
  
  <p>I would rather do this outside of Spring Security or OAuth if possible. I have also read that sending username and password over SSL is enough for authentication. In this case, the app would have a "username" and password and it would send it with every request to the REST service. But how would it keep that information secret if the client is  just HTML and javascript in the browser?</p>
  
  <p>Thanks.</p>