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).
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 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).