Security

Security is one of the first concerns of people deploying a Wireless LAN, the 802.11 committee has addressed the issue by providing what is called WEP (Wired Equivalent Privacy) [ A Technical Tutorial on the IEEE 802.11 Protocol, by Pablo Brenner].

The main concerns of users are that an intruder would not be able to:

• - Access the Network resources by using similar Wireless LAN equipment, and
• - Be able to capture the Wireless LAN traffic (eavesdropping)

Preventing Access to Network Resources

This is done by the use of an Authentication mechanism where a station needs to prove knowledge of the current key; this is very similar to the Wired LAN privacy, on the sense that an intruder needs to enter the premises (by using a physical key) in order to connect his workstation to the wired LAN.

Eavesdropping

Eavesdropping is prevented by the use of the WEP algorithm, which is a Pseude Randon Number Generator (PRNG), initialized by a shared secret key. This PRNG outputs a key sequence of pseude-random bits equal in length to the largest possible packet, which is combined with the outgoing/incoming packet producing the packet transmitted in the air.

The WEP algorithm is a simple algorithm based on RSA?s RC4 algorithm, which has the following properties:

• Reasonable strong: Brute-force attack to this algorithm is difficult because of the fact that every frame is sent with an Initialization Vector, which restarts the PRNG for each frame.
• Self Synchronizing: The algorithm synchronized again for each message, this is needed in order to work on a connectionless environment, where packets may get lost (as any LAN).