Subject: [dhcwg] Authentication for stateless DHCPv6

From: Stig Venaas <[email-masked]>
Date: Thu, 9 Dec 2004 10:24:44 +0100

Jinmei,

We had some discussion earlier on how to do authentication of
information-request - reply without requiring any state on the
server.

I believe this is possible using the mechanism described in appendix
A of RFC 3118. The idea is to have a master key MK that the server
can use for computing they key for any given client. So for a given
client with a given DUID D, you can compute the respective key K_D
as MAC(MK, D) where MAC is a keyed one-way function. This means that
the only state needed on the server is the master key, it doesn't
need to store keys per client.

For the above to work, a client must include the Client Identifier
option in the information-request. At least section 18.1.5 of RFC
3315 has some text saying it SHOULD be included in general, and that
it MUST be included if the information-request will be authenticated.

The replay detection field should not be an issue. By using e.g. a
time stamp there's no per client state.

What do you think? I think it's doable, or am I missing something?

If this solution works, then the situation for stateless DHCPv6 is
not as bad as draft-ietf-dhc-dhcpv6-clarify-auth-00.txt indicates.

Stig

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From: JINMEI Tatuya / 神明達哉<[email-masked]>
Date: Fri, 10 Dec 2004 20:06:35 +0900

>>>>> On Thu, 9 Dec 2004 10:24:44 +0100, 
>>>>> Stig Venaas <[email-masked]> said:

> What do you think? I think it's doable, or am I missing something?

Thanks for the information, I've not been aware of the appendix.  I've
still not read it, but the mechanism seems to provide a reasonable
solution to the problem we are facing.  I'll look into the original
document later.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					[email-masked]