WEP Authentication
An access point must authenticate a station before the station can associate with the access point or communicate with the network. The IEEE 802.11 standard defines two types of WEP authentication: Open System and Shared Key.· Open System Authentication allows any device to join the network, assuming that the device SSID matches the access point SSID. Alternatively, the device can use the "ANY" SSID option to associate with any available access point within range, regardless of its SSID.· Shared Key Authentication requires that the station and the access point have the same WEP Key to authenticate. These two authentication procedures are described below.The WEP Open System authentication process is illustrated in below.
Figure B-2: 802.11 open system authenticationThe following steps occur when two devices use Open System Authentication:1. The station sends an authentication request to the access point.2. The access point authenticates the station.3. The station associates with the access point and joins the network.The WEP Shared Key authentication process is illustrated in below.
Figure B-3: 802.11 shared key authenticationThe following steps occur when two devices use Shared Key Authentication:1. The station sends an authentication request to the access point.2. The access point sends challenge text to the station.3. The station uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and sends the encrypted text to the access point.4. The access point decrypts the encrypted text using its configured WEP Key that corresponds to the station's default key. The access point compares the decrypted text with the original challenge text. If the decrypted text matches the original challenge text, then the access point and the station share the same WEP Key and the access point authenticates the station.5. The station connects to the network.If the decrypted text does not match the original challenge text (i.e., the access point and station do not share the same WEP Key), then the access point will refuse to authenticate the station and the station will be unable to communicate with either the 802.11 network or Ethernet network.
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