Validating ASP.Net application Initiated By Cognos

[LGavin]

I am writing a series of ASP.Net applications that will be initiated from the Cognos portal. I understand that Cognos will pass the logged on user name in a request parameter, along with the CAM passport. How can I call Cognos (using the Cognos SDK) from the ASP.Net application to validate that the user name and CAM passport came from Cognos, and that a user didn't simply type in the application's URL supplying the user name and CAM passport value as parameters? A code sample would be great!