Options to make this happen:

a) Make the GSS-EAP client aware of the AS exchange and give it the
bits it needs to recover the reply key and extract the credentials.
Now how to get a service ticket for the RP in a round-trip efficient
way?  Well, have the RP mint one and be done, say.  Or define a new
way to use a TGT as an additional ticket with which to get the desired
service ticket (sortof like reverse user-to-user).

b) Define a new AS-like exchange where the final reply in a successful
case contains a KRB-CRED, so that multiple tickets may be issued at
once, then apply the solution above this one.

c) Add some AS-REQ flags so that the AS-REP will contain an pre-auth
element that contains a KRB-CRED in it with the desired tickets.  In
this case the enc-part of the AS-REP will be useless and will be
thrown out.

d) Add some AS-REQ flags so that the AS-REP's pre-auth method data
will contain an embedded KRB-CRED (in the case of GSS pre-auth
probably using the Null enctype and embedded in a wrap token).

It all sounds rather messy to me.  Desirable, yes, but also messy.

(d) implies that the pre-auth plugin on the KDC must have access to
all details of the AS-REQ.  Probably not a big deal.  It also implies
that the pre-auth plugiin must have some way to get the desired
tickets minted, which sounds like a fairly major abstraction
violation, but one I could make peace with.

(a), (b), and (c) would make GSS-EAP as a protocol have too much
Kerberos knowledge for my comfort.

I think (d) is the best option, then.

The best part of this though is that it gives you a reason to want GSS
pre-auth ;)

Nico
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