Wired equivalent privacy, WEP, is a security protocol specified in IEEE 802.11 standard for protecting wireless network users from hacking. The aim of WEP is to provide the same degree of confidentiality as hard wired systems.
When WEP is activated on a wireless network, each 802.11 packet is encrypted in an RC4 coded stream generated by a 64 bit key. This key is made up of a 24 bit IV (initialisation vector) and a 40 bit WEP key. The encrypted key is generated by an XOR (exclusive OR gate) between the original packet and the RC4 data stream. The IV is chosen by the sender and can be modified from time to time so that the packets are not all encrypted with the same stream.
In 2004, WEP was superseded by WPA (Wi-Fi Protected Access), and the current implementation is WPA-2.