Encryption on a wireless network
Wireless access points and wireless routers such as the Linksys WRT54G usually offer multiple types of encryption. Encryption algorithms scramble data before it is sent over the network, making it unreadable to outsiders. Encryption can dramatically improve the security of your wireless network. Most wireless routers for home use offer Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA) encryption. At this moment, they are the most common types of encryption. Both WEP and WPA have a number of subtypes that each offer a different level of security.
WEP encryption is a rather weak type of encryption, but is offered by nearly every wireless router or access point. WEP encryption is often cosidered to weakfor the proper security of your network. It is relatively easy to crack the WEP key using programs like WEPcrack, WEPdecrypt and Airsnort.
A WEP key consists of two parts. A shared key, that is the same on every computer in the network and secondly an 'initilization vector'. The initilization vector or IV is a variable part of the key. The IV is rather short for WEP, just 24 bits. It therefor takes a relatively short time before the same IV is used for a second, third, etc time. On a busy network an attacker could analyze the similarities between these packets and discover their shared value: the network key. On top of that, WEP doesn't encrypt packet headers, making them readable to anyone in range of your wireless network
WPA solves WEPs 'weak headers' problem. WPA uses 'autonomous rekeying'. WPA's Temporal Key Integrity Protocol (TKIP) periodically changes the key that is used to encrypt data, making it harder for attackers to find similarities between packets. TKIP greatly improves wireles network security.
The toughest encryption type available at this moment is called Advanced Encryption Standards (AES) or 'Rijndael', an encryption algorithm created by two Belgian computer scientists. In 2001, the American government has chosen AES as its standard for securing sensitive government information. AES is currently the strongest type of encryption available for wireless network security. The Linksys WRT54G wireless router supports AES.
In the following pages you will learn how to secure your wireless network using WEP or WPA/TKIP encryption on the Linksys WRT54G wireless router. After securing the router you will configure a computer to connect to the router using the correct encryption settings. I have taken examples from Windows XP with Service Pack 2 to illustrate this task. Remember though, that the principles shown apply to wireless networks (and the computers using them) in general.