eap Mailing List: Re: Approach to channel bindings (Was; Re: [eap] Basic facts about EAP)

[Yoshihiro Ohba (yohba]

Hi Jari,

On Tue, May 03, 2005 at 03:22:23PM +0300, Jari Arkko wrote:
> >
> I wonder if we are talking about the same thing here. I agree with
> what you say is needed, but it seems like the above is more like the
> secure capabilities negotiation requirement that we have placed on
> the Secure Association Protocol.

It looks like so.  In fact, I am currently thinking that (so-called)
channel binding should be part of secure association.

> 
> As others have pointed out, the term channel binding may not be
> the best choice. But at least the way it is defined in RFC 3748 and
> the keying draft it seems to talk about an ability to match two
> independent sources of information to each other:
> 
> Using such a protected exchange, it is possible to match the channel
> properties provided by the authenticator via out-of-band mechanisms
> against those exchanged within the EAP method. Where discrepancies
> are found, these SHOULD be logged; additional actions MAY also be
> taken, such as denying access.
> 
> To me this implies that we can't get this type of channel binding
> without exchanging information on all sides of the peer - auth - server
> triangle.

Yes.

> 
> But perhaps we are talking about who should make the final
> check, is it the peer, authenticator, server, or all of them. 

I think this is a good catch of the essentials.

> I've
> been assuming it would be either the peer or the server, or
> possibly both of them. What you have said has lead me to
> reconsider this a bit. Perhaps all of the parties have an interest
> in making sure the others are not fooling them.

Thank you,

Yoshihiro Ohba

> 
> --Jari
>