m globally as the WLAN standard. It has a test system which certifies products as interoperable with other WFA-certified products.
One of the trade-offs of Wi-Fi technology is still the security issue (Fougere, 2003). Initially, there was the need to have security manageable in software within the Wi-Fi NIC (network interface card), which resulted in an approach called 40-bit WEP (wired equivalency protection), but this proved to have too high a vulnerability level. WEP mechanisms implement the confidentiality and integrity of the traffic on a network (Uskela, 1997). WEP uses the RC4 PRNG algorithm based on a 40-bit secret key and a 24 bit initialization vector sent with the data. Each Medium Access Control Protocol Data Unit (MPDU) frame includes the clear text Initialization Vector (IV) and Integrity Check Vector (ICV) as well as the cipher text data block so the receiver can always decrypt the cipher text block and check its integrity. The actual algorithm used is not public, but the secret key is only 40 bits long and can easily be solved in less than two seconds by hardware costing less than $100 in the hands of hackers.
Now the IEEE is working on 802.11i, a security standard that is still in the works and not yet available (Fougere, 2003). Meanwhile, the WFA has developed what is known as WPA (Wi-Fi Protected Access), which provides stronger authentication and encryption than the original 802.11 standards. Interoperability testing is currently underway, but only for Windows XP, and the system is expected to be available in the next few months. When it will be available for other operating systems is not known. There is also some question as to how effective it will be to institute, because it requires a new client and enhancements to the RADIUS Server. It may also be vulnerable to hackers who can pose as an access point and hijack a userÆs session.
Another problem for radio-based systems is eavesdropping ...