ZyXEL Communications NBG-418N v2 User Manual page 215

A 256-bit Pairwise Master Key (PMK) is derived from the authentication process by the RADIUS server and
3
the client.
The RADIUS server distributes the PMK to the AP. The AP then sets up a key hierarchy and management
4
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.
Fig ure 147 WPA(2) with RADIUS Application Example
WPA(2)- PSK Applic a tio n Exa m ple
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 consist
1
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
2
matches.
The AP and wireless clients generate a common PMK (Pairwise Master Key). The key itself is not sent over
3
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 exchanged
4
in a handshake to create temporal encryption keys. They use these keys to encrypt data exchanged
between them.
Appendix E Wireless LANs
NBG-418N v2 User's Guide
215