Joe,
First, after some discussion with some of the users of this spec from
3GPP, we have decided that AT_KDF=1 or the AKA fallback mode should be
removed.
AT_KDF_INPUT field values would indeed be dependent on which KDF is
used. I will make the second change you suggested to fix this.
On the network name: the client and the network execute the same
algorithm to determine the network name. It has to be done by both, as
otherwise we could not compare the two and the key derivation would not
be very useful. There are obviously several ways in which the comparison
could be carried out, transporting information in one or the other
direction or both. The authors have chosen a particular model which is
simple from a protocol perspective and gives more responsibility for the
end host to deal with policy decisions upon a mismatch. There are
different tradeoffs with other models, but I'm not necessarily convinced
that they would be superior. I do note as well that centralized policy
and other management tools blur the distinctions a bit. I will, however,
change the text because the intent was to require that the check be
always made, but allow a policy driven decision on whether to abort or
to continue with a warning.
Jari
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