Subject: [Mipshop] IESG evaluation - Steve Bellovin's comments

From: "Soliman, Hesham" <[email-masked]>
Date: Tue, 21 Sep 2004 22:22:56 -0400

Steve, 

Thanks for your comments. Your comment and responses
below.

>	The Security Considerations section says:
>
>  It is crucial
>  that the security relationship between the mobile node and the MAP is
>  of strong nature; it MUST involve mutual authentication,

>but there is no hint of how this can be done.  In particular, how does the mobile node know >that the MAP is *authorized* for that role?  This is much worse than the ordinary MIPv6 
>situation, since in the normal case you're dealing with an on-link forwarder where the 
>added risk is low.  (The risk is high, but the added risk from MIP is low, and SEND helps 
>with the normal risk -- but not for this.)  

=> I'm not sure why you think it's worse than normal MIPv6. Let me 
explain why I don't think it's worse. The SA established between
the MN and the MAP is currently using IKE. Of course this can be 
done using preconfigured keys or dynamically. Preconfigured keys
are probably not workable in the general case so let's focus on 
the dynamic scenario. It involves the following:

1. Discovering the IP address of the MAP
2. Negotiating the SA using IKE (exchanging certificates)
3. Establishing the SA

I'm guessing you refer to step 1. The IP address is learnt
from the RA. If the question is: how do we know the RA
came from a real router and not a rogue one? Then the answer 
is either: a) the MN is on a point to point secure link (e.g.
cellular) or b) on a shared link with no link layer security. 
If b) then SEND can be used, however, this is a general problem
not specific to this proposal. 
Once this step is achieved then steps 2 and 3 should be 
ok. Did I understand your concern correctly?

>I don't expect a solution in this document, but 
>the problem needs to be discussed.  I believe there's some good text in one of the SEND >
>documents that can be used.

>Beyond that, the document also says "the MAP does not need to know the identity of the 
>mobile node".  This contradicts the previous statement about mutual authentication.  I 
>believe I know what they mean, but it isn't clearly enough expressed in the document.

=> Sure, this can be changed to
   "The MAP need not have any prior knowledge of the mobile node's
    identity"
How's that?

Thanks,
Hesham

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