RE: [KAML] Reminder: BOF proposals to me by October 1

"Josh Howlett" <Josh.Howlett@ja.net> Mon, 19 November 2007 11:23 UTC

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Subject: RE: [KAML] Reminder: BOF proposals to me by October 1
Date: Mon, 19 Nov 2007 11:23:11 -0000
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From: "Josh Howlett" <Josh.Howlett@ja.net>
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> On Nov 16, 2007 5:54 PM, Josh Howlett <Josh.Howlett@ja.net> wrote:
> > >
> > > With regard to (1), I think you're missing the point, Josh.
> > > How the LoA is carried in the SAML assertion is a 
> technical detail, 
> > > not a matter of policy.
> >
> > My point was that if the <LoA token> can be acquired post 
> hoc then the 
> > Relying Party can decide itself what is the necessary 
> token(s), rather 
> > than relying on the TGS to choose what it believes is 
> appropriate. The 
> > fire-and-forget approach does not provide room for agility.
> 
> I don't believe it works that way, Josh.  An RP that resolves 
> a token reference receives the same token that would 
> otherwise be received by value.  The act of authentication 
> has already taken place, so there is very little wiggle room, 
> in fact.  You may as well push the token up front in that case.

Aaaah, I now understand how we're getting our wires crossed.

I wasn't suggesting binding an artifact to the ticket; instead, I was
assuming that the RP is wielding a NameID (bound to the ticket) that can
be used, for example, as the <Subject> of an <AuthnQuery>; the AuthN
context may then be returned within an Authentication Statement.

(I think that dereferencing an artifact in this context is possibly
difficult for other reasons, but that's another discussion...)

FWIW, another reason that 'push' might be problematic is that the Ticket
Granting Service may not be aware of the authentication context owing to
the fact that the Authentication Service (in the Kerberos context!) that
the principal authenticates against may be a separate entity from the
TGS; how, therefore, does the TGS learn of the AuthN context from the
AS? You could signal this in the TGT perhaps, but this is adding
complexity.

Further, if we assume that the Authentication Service is issuing the
Authentication Assertion (with the LoA) then some other possible issues
resolve themselves; for example, we know that we can set the value of
the NotOnOrAfter attribute to the expiry of the principal's Kerberos
TGT.

josh.

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