Encryption; User Authentication; Wpa(2)-Psk Application Example - ZyXEL Communications ZyXEL ZyAIR G-570S User Manual

Key differences between WPA(2) and WEP are improved data encryption and user
authentication.
If both an AP and the wireless clients support WPA2 and you have an external RADIUS
server, use WPA2 for stronger data encryption. If you don't have an external RADIUS server,
you should use WPA2-PSK (WPA2-Pre-Shared Key) that only requires a single (identical)
password entered into each access point, wireless gateway and wireless client. As long as the
passwords match, a wireless client will be granted access to a WLAN.
If the AP or the wireless clients do not support WPA2, just use WPA or WPA-PSK depending
on whether you have an external RADIUS server or not.
Select WEP only when the AP and/or wireless clients do not support WPA or WPA2. WEP is
less secure than WPA or WPA2.

6.10.1 Encryption

Both WPA and WPA2 improve data encryption by using Temporal Key Integrity Protocol
(TKIP), Message Integrity Check (MIC) and IEEE 802.1x. In addition to TKIP, WPA2 also
uses Advanced Encryption Standard (AES) in the Counter mode with Cipher block chaining
Message authentication code Protocol (CCMP) to offer stronger encryption.
The encryption mechanisms used for WPA(2) and WPA(2)-PSK are the same. The only
difference between the two is that WPA-PSK uses a simple common password, instead of
user-specific credentials. The common-password approach makes WPA(2)-PSK susceptible to
brute-force password-guessing attacks but it's still an improvement over WEP as it employs
an easier-to-use, consistent, single, alphanumeric password.

6.10.2 User Authentication

WPA or WPA2 applies IEEE 802.1x and Extensible Authentication Protocol (EAP) to
authenticate wireless clients using an external RADIUS database.

6.11 WPA(2)-PSK Application Example

A WPA(2)-PSK application looks as follows.
1 First enter identical passwords into the AP and all wireless clients. The Pre-Shared Key
(PSK) must consist of between 8 and 63 ASCII characters (including spaces and
symbols).
2 The AP checks each client's password and (only) allows it to join the network if it
matches its password.
3 The AP derives and distributes keys to the wireless clients.
4 The AP and wireless clients use the TKIP or AES encryption process to encrypt data
exchanged between them.
Chapter 6 Wireless Screens
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