Subject: [Mip6] Combining Pre-Configured KBMs w/ CoA Tests

From: Christian Vogt <[email-masked]>
Date: Fri, 12 Nov 2004 11:31:24 -0500

Hi MIP6 folks,

even though Charlie cannot make it to today's MIP6 session, and there
won't be a presentation of the latest version of the pre-configuration
ID [1], I want to re-visit the possibility to combine pre-configuration
with a CoA test. We had a thread on the MIP6 mailing list in March this
year where some people, including me, argued that such a combination may
be useful in scenarios where there is an opportunity to pre-configure
MNs and CNs, but there still is no trust relationship btw. the MNs and
CNs [2]. A 3G mobile operator is probably a good example for this.

The idea back in March was to interpret the pre-configured key as a Home
Keygen Token, and let the MN do the CoA test in order to gain a Care-of
Address Token. The MN could then calculate a KBM just as in RFC 3775 [2].

Due to some changes Charlie meanwhile applied to the pre-configuration
ID, this idea now requires slight revision. In the current ID, the MN is
pre-configured with the Kcn, a home nonce, and a care-of nonce.
Calculation of the KBM can so be achieved as defined in RFC 3775.

Hence, in order to combine pre-configuration with a CoA test, one would
simply have to omit pre-configuration of the care-of nonce. The MN would
thus have to acuire the Care-of Keygen Token through a CoA test rather
than calculating it from a pre-configured care-of nonce.

(Note: One may prefer to use two Kcn's instead of a single one -- Kcn1
would be configured into the MN to calculate the Home Keygen Token, and
Kcn2 would be used by the CN to come up with the Care-of Keygen Token
during the CoA test. Of course, one could use the same Kcn in both the
MN and the CN. But then it might be easier for a MN to spoof the Care-of
Keygen Token.)

The above proposal is IMO appealing because it re-uses the CoA-test
technique from RFC 3775.

- Christian

[1] http://www.ietf.org/internet-drafts/draft-ietf-mip6-precfgkbm-01.txt
[2] http://www1.ietf.org/mail-archive/web/mip6/current/msg00856.html,
http://www1.ietf.org/mail-archive/web/mip6/current/msg00795.html

-- 
Christian Vogt, Institute of Telematics, University of Karlsruhe
www.tm.uka.de/~chvogt/

"I love fools’ experiments. I am always making them." (Charles Darwin)

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