Subject: [eap] Use of EMSK?

From: David Mitton <[email-masked]>
Date: Wed, 05 Oct 2005 23:39:38 -0400

In reviewing the design of a session resumption feature or 
re-authentication, it seems tempting to use the EMSK as keying 
material, as it often not exposed to the network.

I went looking to see if anyone else has done this, but only found 
RFC 3748 saying it's reserved for future definition.  Back at IETF 
58, we got a short presentation on draft-salowey-eap-key-deriv-02.txt
by J. Salowey, P. Eronen.  But I cannot figure out what became of this issue.

Dave.

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From: Jari Arkko <[email-masked]>
Date: Thu, 06 Oct 2005 17:34:00 +0300

Hi Dave,

The history is that EMSK usage rules were incorporated
in the EAP Keying Framework draft, a WG item. However, since
we are having problems completing this work, decided in IETF-62
to split the draft in two. The other part, extensions, now contains
the rules:

http://www.drizzle.com/~aboba/EAP/draft-aboba-eap-keying-extns-00.txt

Anyway, the use EMSK should be possible, if you have provided
sufficient explanation of the specific use to convince that the
security is well thought out. In terms of dependencies, we think
that this requires the above document to complete. But if there's
demand, perhaps we could move the EMSK/AMSK "IANA" rules to
the keying framework (but we would not define your or anyone
else's usage for you; you'd have to do that by yourself).

--Jari

David Mitton wrote:

> I went looking to see if anyone else has done this, but only found RFC 
> 3748 saying it's reserved for future definition. Back at IETF 58, we 
> got a short presentation on draft-salowey-eap-key-deriv-02.txt