title: Widget Security
body: <p>I am working on a javascript widget that will allow users to sign-up for a list. This widget will be embeddable on customer websites. Because it is all client-side driven, minus the requests back to the server. I've been trying to come up with ways to make the widget "secure" in essentially a way to limit the widget to be loaded on only approved sites. </p>
  
  <p>Google Maps seems to be able to use the key they provide to you to do a look-up of the site loading the map. Something to that effect would be perfect. </p>
  
  <p>Widget design: Javascript inserts HTML into DOM. Also adds an iframe element. The iframe loads the form from my site to handle the requests. A key is passed to iframe URL to load the form settings. </p>
  
  <p>Not really looking for code, pseudo code is perfect, just lost on the technique. </p>