This book constitutes the thoroughly refereed post-proceedings of the Third European Workshop on Security and Privacy in Ad hoc and Sensor Networks, ESAS 2006, held in Hamburg, Germany in September 2006 in conjunction with the 11th European Symposium on Research in Computer Security (ESORICS 2006). The papers present original research on all aspects of security and privacy in wireless ad hoc and sensor networks.

It was a pleasure to take part in the 2005 European Workshop on Security and Privacy in Ad Hoc and Sensor Networks (ESAS 2005), held on July 13-14 in Visegrad (Hungary) in conjunction with the First International Conference on Wireless Internet (WICON) . As Program Co-chairs, we are very happy with the outcome of this year's ESAS workshop. It clearly demonstrates the continued importance, popularity andtimeliness oftheworkshop'stopic: securityandprivacy inadhocandsensor networks.Atotalof51fullpapersweresubmitted.Eachsubmissionwasreviewed by at least three expert referees. After a short period of intense discussions and deliberations, the Program Committee selected 17 papers for presentation and subsequent publication in the workshop proceedings. This corresponds to an acceptance rate of 33% - a respectable rate by any measure. First and foremost, we thank the authors of ALL submitted papers. Your con?dence in this venue is much appreciated. We hope that you will continue patronizing ESAS as authors and attendees. We are also very grateful to our colleagues in the research community who served on the ESAS Program C- mittee. Your sel?ess dedication is what makes the workshop a success. Finally, we are very grateful to the ESAS Steering Group: Levente Buttyan, Claude Castelluccia, Dirk Westho? and Susanne Wetzel. They had the vision and the drive to create this workshopin the ?rst place; they also provided many insightsandlotsofhelpwiththisyear'sevent.Weespeciallyacknowledgeand- preciate the work of Levente Buttyan whose dedication (as Steering Committee member, PC member and Local Arrangements Chair) played a very important role in the success of the workshop.

Ad hoc and sensor networks are making their way from research to real-world deployments. Body and personal-area networks, intelligent homes, environmental monitoring or inter-vehicle communications: there is almost nothing left that is not going to be smart and networked. While a great amount of research has been devoted to the pure networking aspects, ad hoc and sensor networks will not be successfully deployed if security, dependability, and privacy issues are not addressed adequately.

As the first book devoted to the topic, this volume constitutes the thoroughly refereed post-proceedings of the First European Workshop on Security in Ad-hoc and Sensor Networks, ESAS, 2004, held in Heidelberg, Germany in August 2004. The 17 revised full papers were carefully reviewed and selected from 55 submissions. Among the key topics addressed are key distribution and management, authentication, energy-aware cryptographic primitives, anonymity and pseudonymity, secure diffusion, secure peer-to-peer overlays, and RFIDs.