title: Creating a post with hidden inputs to Azure ACS to avoid redirect to login page
body: <p>I have successfully linked ACS to ADFS and our website user's authenticate against ADFS without issue.
  I also have legacy sites that authenticate directly against AD via custom code and IAG. </p>
  
  <p>We would like the users of the legacy site, once authenticated, to bypass having to login again to enter our new sites. Removing IAG is not an option at this moment. </p>
  
  <p>I have the ability to add additional pages to the legacy site and I can create addition IP's in ACS. My attempt so far has been to create a self signed cert, generate a federatedmetdata.xml based on that cert file and import that into ACS. That went well. Then I wanted to try and create the WSResponse  and claims for the WSignin1.0 request and post that to ACS using the same cert I used to create the metadata file. That action would occur from the legacy site. That has not went so well as I usually receive a HTTP error code of 500 with the "ACS20001: An error occurred while processing a WS-Federation sign-in response" from ACS.
  Basically I would like to know if what i am doing is feasible? , or perhaps there is a better way given the constraint of IAG, or if I am close and should continue down the path I am on.  </p>