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EAP Scenarios and 802.1af. Joseph Salowey jsalowey@cisco.com 1/12/2006. Basic EAP Model. Authentication. EAP Server. EAP Peer. EAP Authen- ticator. Keys. AAA Model. Authentication. AAA Server. EAP Server. EAP Peer. EAP Authen- ticator. Keys.
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EAP Scenarios and 802.1af Joseph Salowey jsalowey@cisco.com 1/12/2006
Basic EAP Model Authentication EAP Server EAP Peer EAP Authen- ticator Keys
AAA Model Authentication AAA Server EAP Server EAP Peer EAP Authen- ticator Keys (Authorization)
AAA Model Notes • Peer authenticates AAA server • AAA server provides authenticator with key • Possession indicates to peer that authenticator is authorized • Peer does not know the identity of the authenticator, by default it can’t differentiate between authenticators • Authenticator receives authorizations from AAA server
3rd Party Authentication Model Authentication EAP Authen- ticator EAP Server EAP Peer (Online or Offline) Authentication Services
3rd Party Authentication ModelNotes • Peer authenticates the authenticator • Peer knows the authenticator’s identity • Peer must be able to authorize based on identity information • Authenticator does not get authorization based on authentication exchange • Authentication service may be offline as in PKI CA • Authentication service may be online as in Kerberos
Approaches to modifying the AAA model (“channel bindings”) • Bind authenticator/service identity into EAP exchange • EAP methods do not interpret the data, instead transport data • Draft-arkko-eap-service-identity-auth-04 • Specify target authenticator/service • Mechanism dependent implementation (kerberos, channel binding, credential selection) • Bind authenticator/service identity to key material • Draft-obha-aaa-key-binding-01
3rd Party authentication case Mutual Authentication SW1 SW2 Authentication Services (offline)
Unilateral AAA case Mutual Authentication SW1 SW2 AAA
Bilateral AAA case Mutual Authentication x 2 AAA SW1 SW2 AAA AZ AZ
EAP and keys • EAP methods can derive key material • MSK available to the authenticator • EMSK reserved (for derivation of other keys TBD) • MSK may be used to derive session keys data encryption (802.11i) • MSK may be used to derive KEK to encrypt key descriptor to distribute keys (group keys) • Either or both approaches may be useful for CAK establishment