Security of IEEE 802.11 Systems

The IEEE 802.11 provides for MAC access control and encryption mechanisms. Earlier,
the wire line equivalent privacy (WEP) algorithm was used to encrypt messages. WEP uses a Rivest Cipher 4 (RC4) pseudo-random number generator with two key structures
of 40 and 128 bits. Because of the inherent weaknesses of the WEP, the IEEE 802.11i committee developed a new encryption algorithm and worked on the enhanced security and authentication mechanisms for 802.11 systems.

For access control, ESSID (also known as a WLAN service area ID) is programmed into each AP and is required in order for a wireless client to associate with an AP. In addition, there is provision for a table of MAC addresses called an access control list to be included in the AP, restricting access to stations whose MAC addresses are not on the list.

Beyond layer-2, 802.11 WLANs support the same security standards supported by other 802 LANs for access control (such as network operating system logins) and encryption (such as IPSec or application-level encryption). These higher-level technologies can be used to create end-to-end secure networks encompassing both wired LAN and WLAN components, with the wireless piece of the network gaining additional security from the IEEE 802.11i feature set.

Source of Information : Elsevier Wireless Networking Complete