wireless authentication protocols

How WLAN Authentication Works

802.11 networks use two authentication methods: open-system authentication and shared-key authentication. In both schemes, each mobile client (called a station) must authenticate to the access point. Open-system authentication might better be called "no authentication", because no actual authentication takes place: the station says "please authenticate me", and the AP does so, with no credential exchange. Shared-key authentication is somewhat more robust (except that it depends on WEP). The station requests authentication, and the access point (AP) responds with a WEP-encrypted challenge. The station can decrypt the challenge and respond only if it has the correct WEP password. In both of these methods, the station must also know the service set identifier (SSID) of the AP. However, because the AP might broadcast its SSID, and because stations talking to that SSID always broadcast it, this behavior isn't much of an obstacle to learning the SSID.