eap Mailing List: RE: RE: channel binding

[Yoshihiro Ohba (yohba727]

Hi Joe,

Thank you for prompt response.  Please see my comment below.

> From: "Salowey, Joe" <jsalowey [at] cisco.com>
> To: "Yoshihiro Ohba" <yohba727 [at] hotmail.com>
> CC: <eap [at] frascone.com>
> Subject: [eap] RE: channel binding
> Date: Mon, 8 Aug 2005 09:19:40 -0700
>
> >
> > I don't understand this, as we are not discussing the case
> > where EAP derived keys are not used.
>
> [Joe] We are discussing the capabilities of an EAP-method.  Although an
> EAP-method can generate keys there is nothing forcing those keys to be
> used for anything.  Binding data to the authentication exchange and
> binding data to the key derivation are similar but different approaches.

Although I agree that binding data to the authentication exchange and 
binding data to the key derivation are different approaches, I don't agree 
with using keys generated by an EAP method 
for arbitrary purpose, especially AAA-Key.  I think there is a key-scoping 
issue if we do not specify the usage of the keys generated by an EAP 
method.  At least AAA-Key should be restricted to be used by a specific 
pair of EAP peer and authenticator. Also, this is also related to EAP 
applicability statement which currently allows the use of EAP for network 
access authentication, not for authentication for arbitrary application.

Besides this I have two issues on the use of EAP-method based chanel 
binding scheme.
One issue is as described in section 2 of draft-ohba-eap-aaakey-binding. 
The other issue 
is complexity being added to each EAP method by having direct communication 
between each EAP method and lower layer, which is not described in the EAP 
state machine I-D. The latter issue 
issue keeps me away from implementing EAP-method based chanel binding 
scheme in Open Diameter EAP libraries.

Regards,
Yoshihiro Ohba


> I do not think that one should eliminate binding of data in the
> authentication in favor of binding data in the key derivation as they
> solve different problems.  I am not familiar with the EAP-IKEv2 use of
> "channel bindings", but I would rather see the capability fixed if it
> has a problem than removed.
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