Hi Jari,
We seem to agree until we get here snip:
Avi wrote:
> >It is basically this, how do I know which ones to
generate during
> >network access authentication? I could have lots
of them.
> Also perhaps
> >during this session the user requested access to a
new
> application. I
> >need a key now. Should I tear down the session
just so I
> can get a new
> >EMSK?
> >
> >
Jari wrote:
> The latter should never happen. If we do the
calculation of
> AMSKs a priori,
> then it needs to be something enabled by the user's
profile. If he is
> authorized to day (say) access handoff, mobile IP, and
some
> QoS exchange,
> then we'd generate three AMSKs for that user.
Perhaps you missed my poorly stated point
What if the user is requesting access to a new application?
which could
also involve the modification of the user's profile.
If EMSK is not there, then what do I do? Restart the
session? No.
At anyrate I belive that there could be other use cases... I
gave two
reason why:
Just-in-time;
Dynamic-Application provisioning.
> >>2. Do you have a plan how to manage the cache
at the AAA
> >>server side, if there is no agreement a priori
that EMSKs and
> >>specific AMSKs are going to be needed?
> >>
> >>
> >
> >EMSK should be bound to a user session. When the
user
> session goes away
> >so should the EMSK. If the user session is
reauthenticated so should
> >the EMSK.
> >
> >
> Ok. This sounds reasonable. There may be still
tradeoffs
> between keeping one EMSK for all sessions vs. keeping
bunch of
> AMSKs for those sessions that have been authorized to
do
> more than pure access.
Hmmmmm... A session is an EAP session (which is one Access
Session) and
you should only have one EMSK for that session. AMSKs are
dervied from
the EMSK belong to that session.
> But its hard for me to quantify this
> tradeoff, given that we don't know how many
applications we could
> in practice be talking about, and in particular we
don't know what
> fraction of users would be authorized to use those
applications.
> Just
> some, or would this be something that is by default
turned on for
> everyone?
IMO that would be deployement issue. We see a very
immediate need for
EMSK and AMSK today which will be used by everyone in the
network -- and
this is the MIP case, but other then that EMSK/AMSK is very
very new.
Wait until 3GPP/2 and OMA learn about it.
Avi
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