RE: SAML shared credential (draft-saml-shared-credential-discussion-01.doc)

My major concern with this proposal is that I don't think it actually
addresses the use case because there's nothing in the SwitchUser extension
that tells the IdP it's supposed to switch from a group to a principal.
That's only implied. It seems like something else is needed, perhaps the
AuthnContext part, but that alone would be sufficient to solve the problem.

I think the TC should decide whether assertions about groups are a
legitimate function, and if they are, we should define a new NameID Format,
in the form of a URI, that represents a group.

In fact, we could go a bit farther, and create a "groups" extension that
defines a URI that is both a NameID Format and an Attribute Name.

-- Scott