title: Single sign on between ASP.NET app and Office365 with on-premise ADFS STS
body: <p>I'm building an ASP.NET web app that authenticates users with Windows Identity Foundation.</p>
  
  <p>The organization has an on-premise ADFS STS. Their Office365 authenticates through Microsoft Federation Gateway with the on-premise STS. The new web app will also authenticate against the on-premise STS with WIF.</p>
  
  <p>Can I establish silent single sign on between the new app and the Office365 environment? So the user will not have to log into Office365 once he is logged into the web app and vice versa.</p>