Subject: Re: [HOKEY] Channel binding/ lying MITM: EMSK Hierarchy Changes

From: "M. Vanderveen" <[email-masked]>
Date: Mon, 12 Feb 2007 09:31:21 -0800 (PST)

Agreed with Michael. We security people tend to get carried away with correctness and the like. End result is no one will implement our specs. I've seen this in practice..

Michaela

----- Original Message ----
From: "[email-masked]" <[email-masked]>
To: [email-masked]; [email-masked]; [email-masked]
Cc: [email-masked]; [email-masked]
Sent: Monday, February 12, 2007 9:01:40 AM
Subject: RE: [HOKEY] Channel binding/ lying MITM: EMSK Hierarchy Changes

Colleagues,

The mention of latency is refreshing. While we need excellent security,
we must also make it possible for seamless mobility to be achieved. We
can't count on MBB with huge handover time budgets to hide long SA setup
times.

Best Regards,
Michael G. Williams 

-----Original Message-----
From: ext Glen Zorn (gwz) [mailto:[email-masked]] 
Sent: Monday, February 12, 2007 7:30 AM
To: Charles Clancy; Narayanan, Vidya
Cc: [email-masked]; Madjid Nakhjiri
Subject: RE: [HOKEY] Channel binding/ lying MITM: EMSK Hierarchy Changes

Charles Clancy <mailto:[email-masked]> allegedly scribbled on Monday,
February 12, 2007 5:28 AM:

> My interpretation of the discussion is that we should do precisely as 
> you describe, except that the RADIUS keyreq packet contain a value 
> MIC'd by an authentication key derived directly from the EMSK (like 
> the rIK/rMSK relationship in EAP-ER), and that MIC'd value should 
> contain the channel binding info.  That way it channel bindings can be

> explicitly validated prior to key distribution.

This assumes a request for a key.  I had assumed that all keys would be
delivered at the same time (e.g., in the RADIUS Access-Accept).  A
separate key request would increase the latency of the reauthentication
considerably, wouldn't it?

...

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From: "Dan Harkins" <[email-masked]>
Date: Mon, 12 Feb 2007 10:17:55 -0800 (PST)

I've also the opposite. Convenience trumps all and you end up with
something like WEP.

  Nobody is suggesting we get carried away but if correctness is not
the goal then incorrectness will be the result.

  Dan.

> Agreed with Michael. We security people tend to get carried away with
> correctness and the like. End result is no one will implement our specs.
> I've seen this in practice..
>
> Michaela
>
>
> Ask your question on
> www.Answers.yahoo.com_______________________________________________
> HOKEY mailing list
> [email-masked]

---

From: Lakshminath Dondeti <[email-masked]>
Date: Mon, 12 Feb 2007 10:30:22 -0800

Yep, agreed.  It is one thing to say "let's not make things 
unnecessarily complex" and an entirely another thing to say 
"correctness" is a luxury.  Actually, Michaela, you may want to clarify 
what you are saying.  Are you really saying correctness as a design goal 
is too much to ask for?

There is definitely a middle ground and that comes from knowing why each 
provision/technique in the protocols and key derivations we design 
exists and being able to clearly explain what can be traded-off for 
efficiency and at what cost.

Lakshminath

---

From: "Glen Zorn \(gwz\)" <[email-masked]>
Date: Mon, 12 Feb 2007 23:02:42 -0800

Dan Harkins <mailto:[email-masked]> allegedly scribbled on Monday,

>   I've also the opposite. Convenience trumps all and you end up with

Dan, please start making sense.  Did you ever try to configure WEP?  If
so, you wouldn't be saying anything about convenience...

---

From: "Dan Harkins" <[email-masked]>
Date: Mon, 12 Feb 2007 23:36:55 -0800 (PST)

Glen,

  WEP is very convenient. It's so convenient that Ma and Pa Kettle can
configure it. You don't even need to say who the secret you are typing
in is shared with, you just type in a secret. It's emminently more
convenient than enrolling something in a certification authority. And it's
easier to configure than a RADIUS client or IKE pre-shared key.

  Sometimes I don't make sense, yes. I meant to say "I've also _seen_
the opposite" but my fingers couldn't keep up with the thought. But I
fail to see how a statement that WEP is convenient to use is nonsensical.
Yes, I've configured WEP. More times than I want to think about. What is
so difficult about it for you?

  Dan.