The current rate of deployment of wireless networks - whether cellular, LAN, Bluetooth, or sensor - is remarkable. Wireless systems are vulnerable to many kinds of attack, and the security features of fixed-line systems are not always applicable in the wireless arena. With ever-increasing amounts of data being carried on wireless networks, security has become a major concern and an area of great commercial importance. This book presents the key features of wireless networks and discusses various techniques for ensuring secure communication. In particular, techniques for dealing with hacking and other forms of attack will be dealt with, as will cooperation in multi-hop and ad hoc networks. It is suitable for senior undergraduates and graduate students of electrical engineering and computer science. Given the breadth of coverage, it will also appeal to researchers and practitioners in the wireless industry.