I am trying to validate a SAML response which is coming from Siteminder IDP from a third party. I have installed the certificate provided by them. When I call the Valida
You are probably missing a configuration that maps the issuer name (as specified inside the token) to the certificate (probably specified with a thumbprint). I guess you solve this with some configuration in your web.config. Have a look at p.e. Microsoft validating issuer name registry The page contains some sample configuration. Setting this up correctly depends entirely on your situation.