ZyXEL Communications WAP6405 User Manual page 138

The AP passes the wireless client's authentication request to the RADIUS server.
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The RADIUS server then checks the user's identification against its database and grants or denies
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network access accordingly.
A 256-bit Pairwise Master Key (PMK) is derived from the authentication process by the RADIUS
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server and the client.
The RADIUS server distributes the PMK to the AP. The AP then sets up a key hierarchy and
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management system, using the PMK to dynamically generate unique data encryption keys. The
keys are used to encrypt every data packet that is wirelessly communicated between the AP and
the wireless clients.
Figure 75 WPA(2) with RADIUS Application Example
WPA(2)-PSK Application Example
A WPA(2)-PSK application looks as follows.
First enter identical passwords into the AP and all wireless clients. The Pre-Shared Key (PSK) must
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consist of between 8 and 63 ASCII characters or 64 hexadecimal characters (including spaces and
symbols).
The AP checks each wireless client's password and allows it to join the network only if the password
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matches.
The AP and wireless clients generate a common PMK (Pairwise Master Key). The key itself is not
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sent over the network, but is derived from the PSK and the SSID.
The AP and wireless clients use the TKIP or AES encryption process, the PMK and information
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exchanged in a handshake to create temporal encryption keys. They use these keys to encrypt data
exchanged between them.
Appendix D Wireless LANs
WAP6405 User's Guide
138