eap Mailing List: Proposed Resolution to Issue 314: AAA-Key Confusion

[Bernard Aboba (bernard_aboba]

The text of Issue 314 is available here:
http://www.drizzle.com/~aboba/EAP/eapissues3.html#Issue%20314

The Proposed Resolution is as follows:

In Section 1.2, change:

"AAA-Key
    A key derived by the peer and EAP server, used by the peer and
    authenticator in the derivation of Transient Session Keys (TSKs).
    Where a backend authentication server is present, the AAA-Key is
    transported from the backend authentication server to the
    authenticator.  In existing usage, the AAA-Key is always derived
    from the MSK and so can be referred to using the MSK name.  AAA-Key
    = MSK(0,63)."

To:

"AAA-Key
The term "AAA-Key" is synonymous with MSK."

In Section 2.1, change:

"  An additional step (phase 1b) is required in deployments which
 include a backend authentication server, in order to transport keying
 material from the backend authentication server to the authenticator.
 In order to obey the principle of Mode Independence, where a backend
 server is present AAA Key transport needs to provide the exported EAP
 keying material and/or derived keys required for derivation of the
 TSKs.  Since existing TSK derivation techniques depend solely on the
 MSK, in existing AAA implementations, this is the only keying
 material replicated in the AAA key transport phase 1b. "

To:

" An additional step (phase 1b) is required in deployments which
 include a backend authentication server, in order to transport keying
 material from the backend authentication server to the authenticator.
 In order to obey the principle of Mode Independence, where a backend
 server is present, all keying material which us required by the lower 
layer needs to
 be transported from the EAP server to the authenticator.
 Since existing TSK derivation techniques depend solely on the
 MSK, in existing implementations, this is the only keying
 material replicated in the AAA key transport phase 1b. "