258
Figure 258 Open system authentication process
• Shared key authentication
Figure 259 s
hows a shared key authentication process. The two parties have the same shared key
configured.
1. The client sends an authentication request to the AP.
2. The AP randomly generates a challenge and sends it to the client.
3. The client uses the shared key to encrypt the challenge and sends it to the AP.
4. The AP uses the shared key to encrypt the challenge and compares the result with that received
from the client. If they are identical, the client passes the link authentication. If not, the link
authentication fails.
Figure 259 Shared key authentication process
Association
A client that wants to access a wireless network via an AP must be associated with that AP. Once the
client chooses a compatible network with a specified SSID and passes the link authentication to an AP,
it sends an association request frame to the AP. The AP detects the capability information carried in the
association request frame, determines the capability supported by the wireless client, and sends an
association response to the client to notify the client of the association result. Usually, a client can
associate with only one AP at a time, and an association process is always initiated by the client.
Other related procedures
1. De-authentication
A de-authentication frame can be sent by either an AP or wireless client to break an existing link. In a
wireless system, de-authentication can occur due to many reasons, such as:
• Receiving an association/disassociation frame from a client which is unauthenticated.
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