6
Security is Achieved by Exchanging Documents
<AuthnRequest>
    <Subject >___</Subject>
</AuthnRequest>
service
provider
Identity
provider
<Response>
    <Assertion>
       <Subject >____</Subject>
       <AuthnStatement AuthnInstant="___">____</AuthnStatement>
    </Assertion>
</Response>
"What authentication information do you have for  this ___ subject?"
"This ___ subject was authenticated by this ___ mechanism,
at this ___ datetime"
The request document
The response document