TTLS (draft-funk-eap-ttls-v0-01.txt) and EAP-FAST (RFC4851) are TLS based methods that can support server only authentication. It was also pointed out that EAP-TLS (draft-simon-emu-rfc2716bis-11.txt) could be modified to create a new EAP method that only requires server side authentication.
In general, in TLS-based EAP methods the TLS client authentication policy is determined by the server. That is, the server decides whether to request a client certificate; RFC 2716 recommends but does not require inclusion of a certificate request in the Server hello message; in the examples in RFC 2716 the certificate-request field is not shown as mandatory. By not including a certificate request, an EAP-TLS server can support anonymous clients. It is my understanding that existing EAP-TLS peer implementations support server-side only authentication.
If the peer can validate the server then it is possible to mitigate many man-in-the-middle attacks against the authentication, however if the peer cannot validate the server then this would leave the protocol open to man-in-the-middle attacks. These TLS based methods require a significant number of round trips, however this may not be an issue especially if the emergency authentication is terminated locally instead of in a home server. There were also several questions raised in the working group during the discussion that might help in further determining the best approach. These are summarized below: 1) It is not clear what security properties are desirable. Is it important for the emergency services network to be authenticated? Is it possible for the peer to have a trust root for emergency services network? Is there expected to be an existing profile with a specific SSID that needs to be authorized? Is there another use for the authenticated identity? 2) What regulatory requirements are driving the need for encryption? This creates some conflicts because encryption without authentication does not satisfy most useful security requirements. 3) Will the authentication for emergency services be terminated locally or in a remote network? What is the tolerance for delay before network connectivity is established? 4) PSK was described as having worse DOS resistance properties that EAP. It seems that in many cases EAP would have worse DOS resistance that PSK, which cases is EAP better? 5) It seems that most public access networks already provide an open access network, why couldn't this network be used for emergency communication? As the 802.11u group is certainly aware, there are other groups within the IETF that are looking at unauthenticated emergency services. In particular, the ECRIT group within the IETF has ongoing work in this area: http://tools.ietf.org/html/draft-schulzrinne-ecrit-unauthenticated-acces s-00 We encourage IEEE working group members to continue the discussion with the IETF in the EMU and the ECRIT working groups.
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