eap Mailing List: Re: Re: Issue 352: Channel Binding Issue

[Yoshihiro Ohba (yohba]

On Tue, May 02, 2006 at 12:26:42PM -0700, Bernard Aboba wrote:
> >Thank you for reading the document.  And the answer is, if the
> >generated "mixed" MSKs are carried in the existing AAA attributes
> >instead of carrying the MSKs, then no AAA attributes or communication
> >flow is required for EAP keying.
> 
> It might be worth saying a few words about this in the paragraph.  

I agree on adding a few words on this in the paragraph.

> Overall, 
> I'm not sure whether the Channel Binding text in the document is all that 
> consistent/comprehesive.


I agree with your opinion here as well.  Let me quote some
questionable part in Section 5.11 of eap-keying-13 below:


"
As noted in [RFC3748] Section 7.15, this vulnerability can be
addressed by EAP methods that support a protected exchange of channel
properties such as endpoint identifiers, including (but not limited
to): Called-Station-Id [RFC2865][RFC3580], Calling-Station-Id
[RFC2865][RFC3580], NAS-Identifier [RFC2865], NAS-IP-Address
[RFC2865], and NAS-IPv6-Address [RFC3162].
"

I'd mention that Channel Binding description in RFC3748 is somewhat
obsolete according to the recent discussion on the AAA server's
requirement on pre-configurating Channel Binding parameters.  Do we
need this paragraph?  Or instead we may have some explicit text here
to obsolete Channel Binding description in RFC3748.


"
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.  For example, see the
discussion in Section 1.4 as well as [I-D.arkko-eap-service-identity-
auth].
"

According to the the AAA server's requirement on pre-configurating
Channel Binding parameters, I don't see the usefulness of
[I-D.arkko-eap-service-identity-auth].  Do we really need this
paragraph?


"
The main difference between these approaches is that Channel Binding
support within an EAP method may require upgrading or changing the
EAP method, impacting both the peer and the server.   Where Channel
Bindings are implemented in AAA,  the peer, authenticator and the
backend server need to be upgraded, but the EAP method need not be
modified.
"

If we have only one Channel Binding method, we don't need this
comparison.


Best regards,
Yoshihiro Ohba