eap Mailing List: RE: Proposed Resolution to Issue 243: State Synchronization

[Walker, Jesse (jesse.walker]

Florent,

Yes, the distributed consensus problem does not admit a solution. But
this is because the protocol does not complete due to network
partitions. If the protocol completes, however, there is a certain
amount of state that must be synchronized, or else the protocol can't be
considered secure under any reasonable definition of secure. This is
what the language "when the EAP method completes successfully" from the
first sentence is supposed to capture. Can you suggest another way to
express this concept?

-- Jesse

-----Original Message-----
From: eap-admin [at] frascone.com [mailto:eap-admin [at] frascone.com] On Behalf
Of Florent Bersani
Sent: Wednesday, July 14, 2004 1:37 PM
To: eap [at] frascone.com
Cc: Bernard Aboba
Subject: Re: [eap] Proposed Resolution to Issue 243: State
Synchronization

I understand what is meant but I feel concerned that "synchronization of

state" may be understood as "common knowledge" (which is impossible to 
reach in a distributed environment with unreliable communications 
http://www.cs.cornell.edu/home/halpern/papers/common_knowledge.pdf - 
using the paper's terminology page 5, what we want here is E or E2 but 
not C that we can't provide).

Though I tried I couldn't figure out some simple wording to reflect this

(but I am still trying to).

Am I the only one that is uncomfortable with this wording?

Bernard Aboba wrote:

>The proposed resolution is to change clause [4] of Section 2.2 to the
>following:
>
>[4]  Synchronization of state.  The EAP method state of the EAP peer
and
>     server must be synchronized when the EAP method completes
>     successfully.  This includes the internal state of the
>     authentication protocol but not the state external to the EAP
>     method,  such as the negotiation occuring prior to initiation of
>     the EAP method.  The exact state attributes that are shared may
>     vary from method to method but typically include the method
version
>     number, what credentials were presented and accepted by both
>     parties, what cryptographic keys are shared and what EAP method
>     specific attributes were negotiated, such as ciphersuites and
>     limitations of usage on all protocol state.  Both parties must be
>     able to distinguish this instance of the protocol from all other
>     instances of the protocol and they must share the same view of
>     which state attributes are public and which are private to the two
>     parties alone.
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