title: Posting user credentials in SAML to a service provider
body: <p>I have been tasked to implement a SSO process for one our internet sites.  I have been reading as much as I can to fully understand SSO and SAML so here goes:</p>
  
  <p>I need to forward to a 3rd party's Service Provider (SP-3rd_party) the credentials a user used to login to our site (SP1).  Then SP-3rd_party will authenticate those credentials against their own Identity Provider.  Then that 3rd party IdP will redirect back to our service with either success or failure.  </p>
  
  <p>Our sites are all written in .NET 4.5.  It seems that we as SP1 should just authenticate against their IdP and not go thru their Service Provider (SP-3rd_party).  Does that make sense?  I feel we are making an additional hop that shouldn't be needed but I am fairly new to all this.  If anyone can provide guidance that would be great.  Thank you!</p>