According to most technology pundits, progress in wireless and sensor networks will lead us into a world of ubiquitous computing, in which myriads of tiny, untethered sensors and actuators will communicate with each other. Information technology will thus deliver its most encompassing and pervasive accomplishment to mankind, promptly taking care of the needs and wishes of everyone. Or maybe not. The described evolution is driven primarily by market forces and vastly ignores the users’ intentions. Yet the recent history of the Internet has shown that these intentions can have devastating effects; for example, spam, viruses, “phishing” and denial of service attacks have unfortunately become commonplace. The misbehavior of a relatively small number of users is leading to a substantial inconvenience to the whole community. Similar or even worse misdeeds are and will be perpetrated in wireless networks. This textbook aims at avoiding that ubiquitous computing becomes a pervasive nightmare. It addresses the following fundamental questions: • How are users and devices identified? • How can a security association be established between two wireless peers? • How can packets be securely and cooperatively routed in a multi-hop network? • How can the fair share of bandwidth between nodes located in the same radio domain be guaranteed? • How do wireless operators behave, if they have to share a given chunk of the spectrum? • How can naturally selfish players be encouraged to behave cooperatively? • And, above all, how is privacy protected? The book treats each of these questions from a theoretical point of view and illustrates them by means of concrete examples such as mesh, ad hoc, vehicular, sensor, and RFID networks.