Wireless LANs can be found nearly everywhere today.Most mobile computersship with built-in wireless LAN hardware by defaultand most other computerscan be equipped with additional hardware.Because all data is transmitted wirelessly, extrasecurity is needed in thesenetworks.This was a concern to the creators of the IEEE802.11 standard, who designed a simple protocolcalled WEP which stands forWired Equivalent Privacy to protect such networks.Unfortunately, the WEP protocol has some seriousdesign flaws and various attacks are possible againstWEP protected networks. This book presents nearly allcurrently known attacks on the WEP protocol,including their theoretical background and theirimplementation. This book is intended for networkoperators, who want to learn more about wirelesssecurity, and also for cryptographers, who want tounderstand the theoretical background of these attacks.