eap Mailing List: Re: Strawman -10/EMSK deletion requirement?

[Rafa Marin Lopez (rafa]

Hi Jari

> First of all, I think this part of the discussion is largely just
> a matter of vague definitions making it hard to make exact
> statements. E.g. where is the line between AAA as a
> "transport" and as an "application" that has intelligence
> to make decisions and grant resources such as keys?
>  
I agree on you this. In my mind the AAA server (where EAP server might 
be co-located) is (or should be) intelligent enough to manage keys from 
users.

> Just to repeat what we have already established, I think
> we have consensus that (a) EMSK is generated by EAP
> methods and that (b) its not going to be shipped away
> to the access devices. In addition, it seems obvious that
> the document we are discussing will not define how AMSKs
> are used or transported.
>  
>
> So the conclusion is that the EMSK is kept somewhere
> between the EAP method and AAA transport layers.
>  
So far, between EAP methods and AAA transpor layers (AAA server?? ) we 
have EAP authenticator layer and EAP layer. An as specified 
draft-ietf-eap-keying-10.txt both layers cannot cache anything. I think 
it does not preclude the use of EMSK but it establishes limits to the 
creation of AMSK. That is, the AMSK should be created just in the moment 
the EMSK is exported. If EMSK wants to be cached, that part of text 
should be relaxed, no?

> I would note that this means that it is, in an IETF sense,
> within a box and not transported via protocols. I don't
> think it makes a lot of sense to debate too long about
> what the internal structure of the box is. I'd be happy
> saying that it resides in the EAP server. I would in
> addition only say the following about the internal
> module structures: The EMSK is not communicated
> either to the lower layer or the AAA transport layer.
> But AMSKs derived from it can be,
> and that any such derivation would have to be defined
> in future documents.
>  
I have seen during discussions and also under my understanding of 
draft-aboba-eap-keying-extns-00.txt that either 1) AMSK would be 
tranported from AAA server to some entity or 2) AMSK could be used as a 
root and cached by the AAA server to derive new keys which would be 
eventually transported to different entities.

will that decision between both cases be specified for application? or 
would it be better to select one approach (it seems people like second one)?

Regards.

--
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Rafael Marin Lopez
Faculty of Computer Science-University of Murcia
30071 Murcia - Spain
Telf: +34968367645    e-mail: rafa [at] dif.um.es
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