Wireless LANs can be found nearly everywhere today. Most mobile computers ship with built-in wireless LAN hardware by default and most other computers can be equipped with additional hardware. Because all data is transmitted wirelessly, extra security is needed in these networks. This was a concern to the creators of the IEEE 802.11 standard, who designed a simple protocol called WEP which stands for Wired Equivalent Privacy to protect such networks. Unfortunately, the WEP protocol has some serious design flaws and various attacks are possible against WEP protected networks. This book presents nearly all currently known attacks on the WEP protocol, including their theoretical background and their implementation. This book is intended for network operators, who want to learn more about wireless security, and also for cryptographers, who want to understand the theoretical background of these attacks.