Another use-case re authentication

We have some use-cases from Northrop, who emailed it directly to use 
(they are IEs in the WG). Here they are in the form they sent for the 
record. I think they can merge into some of the existing use-cases. Some 
of it (SAML, smartcard is only partially covered by the Crypto WG) but 
the digital signing of the tokens credentials for SAML could be done.

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Secure Identity Use-Case:

Single user:

�User is authenticated with username + password

�User is authenticated with username + password and is asked follow up 
questions

�User is authenticated and site key is display or captcha

�User is authenticated with smartcard credentials

�User is authenticated with One Time Password

�User is authenticated with credentials and SAML tokens are generated to 
be used for SSO

Multiple users on a single computer:

�User A is authenticated with username + password to site A

�User B is authenticated with username + password to site A

�User A is authenticated with username + password to site A and is asked 
follow up questions

�User B is authenticated with username + password to site A and is asked 
follow up questions

�User A is authenticated with credentials and SAML tokens are generated 
to be used for SSO

�User B is authenticated with credentials and SAML tokens are generated 
to be used for SSO