You hold in your hands the proceedings of ESAS 2007, the Fourth European Workshop on Security and Privacy in Ad hoc and Sensor Networks. The wo- nd rd shop took place in Cambridge, UK, on the 2 and 3 of July 2007. The workshop was European in name and location but it was de?nitely transatlantic in scope. We had a program chair from Europe and one from the USA, and membership of our program committee was almost evenly split - tween those two regions. When looking at participation, the workshop was even more global than that: the submitted papers came from 25 countries in 6 con- nents. We received 87 submissions. After quick-rejecting 5 papers deemed to be out of scope, the remaining 82 papers were each reviewed by at least three PC members. The two program chairs, who did not submit any works, had sole authoritytodecidewhichpaperstoacceptandreject,basedonlyonthedirective that quality had to be the primary criterion, in order to form a proceedings volume of high international relevance. The number of papers to be accepted was not set in advance: it was selected a posteriori so as to include only solid, innovative and insightful papers. The resulting acceptance rate of about 20%, very strict for a workshop, is a testimonial of how selective we chose to be in accepting only high quality papers.

Inhalt
Device Pairing.- The Candidate Key Protocol for Generating Secret Shared Keys from Similar Sensor Data Streams.- The Martini Synch: Joint Fuzzy Hashing Via Error Correction.- Private Handshakes.- Security Associations in Personal Networks: A Comparative Analysis.- Key Management.- Key Establishment in Heterogeneous Self-organized Networks.- Enabling Full-Size Public-Key Algorithms on 8-Bit Sensor Nodes.- Key Distribution in Mobile Ad Hoc Networks Based on Message Relaying.- Location Verification and Location Privacy.- Distance Bounding in Noisy Environments.- Multiple Target Localisation in Sensor Networks with Location Privacy.- On the Effectiveness of Changing Pseudonyms to Provide Location Privacy in VANETs.- Secure Routing and Forwarding.- End-by-Hop Data Integrity.- Authenticating DSR Using a Novel Multisignature Scheme Based on Cubic LFSR Sequences.- Physical Security.- Security for Mobile Low Power Nodes in a Personal Area Network by Means of Trusted Platform Modules.- ALGSICS Combining Physics and Cryptography to Enhance Security and Privacy in RFID Systems.- Detection of Compromise, and Revocation.- Detecting Node Compromise in Hybrid Wireless Sensor Networks Using Attestation Techniques.- Direct Anonymous Attestation (DAA): Ensuring Privacy with Corrupt Administrators.- New Strategies for Revocation in Ad-Hoc Networks.