Chapter 7 defines three major layers of security: wireless LAN layer, the access control layer, and the authentication layer. This chapter looks at the authentication layer and, more specifically, at the protocols used to implement authentication. IEEE 802.11 lies in the wireless LAN layer, which is considered the lowest layer, and IEEE 802.1X lies in the access control layer. The authentication methods use higher-layer protocols and the term "upper-layer authentication" reflects the fact that the methods do not depend on specific LAN technology. A range of different methods can be used for authentication in RSN; some of the major ones are described here.
We look first at Transport Layer Security (TLS), the default method for WPA that can also be used with RSN. Later in the chapter we look at Kerberos V5 and some of the new methods being invented, such as Protected EAP (PEAP) and the use of cellular phone authentication for Wi-Fi LAN devices (GSM-SIM). We also examine the inner workings of the authentication process and see how the messages are mostly exchanged between the supplicant and the server, with the access point (authenticator) playing a sort of observant go between in the process.