On Sat, Apr 07, 2007 at 04:44:54PM -0400, Charles Clancy wrote:
This is one of the fundamental issues with EAP channel bindings. The
NAS ID is bound to the AAA security association between the
authenticator and the EAP server. The MAC address is visible to the
client. Thus the peer and EAP server each know a different identity for
the authenticator. Whatever identity is used must be channel-bound to
the AAA security association, otherwise the authenticator could lie to
the EAP server about its identity.
I see two solutions:
1. The NAS ID is broadcast to the peer before EAP authentication (e.g.
in an 802.11 beacon)
This is something that IEEE 802.11r/D5.0 is doing. R0KH-ID is set to the
identity of the NAS Client (e.g., NAS-Identifier if RADIUS is used as
the backend protocol) and this identifier is sent to the peer during
association (before EAP authentication). In addition, both the R0KH-ID
(NAS-Identifier) and R1KH-ID (authenticator MAC address) are mixed in
into the key derivation after the EAP authentication.
--
Jouni Malinen PGP id EFC895FA
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