Sensor networks differ from traditional networks in many aspects including their limited energy, memory space, and computational capability. These differentiators create unique security vulnerabilities.Security in Sensor Networks covers all aspects of the subject, serving as an invaluable reference for researchers, educators, and practitioners in the field. Containing thirteen invited chapters from internationally recognized security experts, this volume details attacks, encryption, authentication, watermarking, key management, secure routing, and secure aggregation, location, and cross-layer. It offers insight into attacking and defending routing mechanisms in ad hoc and sensor networks, and analyzes MAC layer attacks in 802.15.4 sensor networks.