title: Custom STS for Web SSO
body: <p>We have an Internet facing Web Application running, and recently our company made some agreements with a 3rd-party company which owns another web site. The idea is to provide access to this external web site to our current customers. Our users will click on an internal link in our solution which will open a new browser window with the third party site. User will not need to authenticate again in the 3rd party company site. 
  We have agreed to issue SAML2 tokens for our users, with a set of claims used by the 3rd-party site to query an present a personalized view to our users</p>
  
  <p>Something important in our scenario is that users are already authenticated in our web site when they decide to access the 3rd-part web site.</p>
  
  <p>What is the best way to implement all this?
  I am thinking on implementing a custom-STS using the WIF SDK to generated those SAML2 tokens and pass then using HTTP POST (cookie) to the 3rd party site. If this is the right approach, then any pointers, tips?
  Will ADFS make any difference?</p>
  
  <p>Thanks for any help</p>