WEP
A security protocol for wireless local area networks (WLANS) defined in the IEEE 802.11b standard. Designed to provide security by encrypting data over radio waves, WEP is not as secure as once believed. It regulates access to a wireless network based on a computer NIC's MAC address, which is relatively simple to be sniffed out and stolen. Used at Layers 1-2, WEP does not offer end-to-end security.
More: Wired Equivalent Privacy