Privacy Enhancing Technologies

The ?rst workshop in this series was held at the International Computer S- ence Institute in Berkeley and was published as LNCS 2009 under the name Workshop on Design Issues in Anonymity and Unobservability. Subsequent Privacy Enhancing Technologies (PET) workshops met in San Francisco in 2002 (LNCS2482)andDresdenin2003(LNCS2760).Thisvolume,LNCS3424,holds the proceedings from PET 2004 in Toronto. Our 2005 meeting is scheduled for Dubrovnik, and we hope to keep ?nding new and interesting places to visit on both sides of the Atlantic or beyond. An event like PET 2004 would be impossible without the work and dedi- tion of many people. First and foremost we thank the authors, who wrote and submitted 68 full papers or panel proposals, 21 of which appear herein. The Program Committee produced 163 reviews in total. Along the way, they were assisted in reviewing by Steven Bishop, Rainer Bohme, Sebastian Clauß, Claudia D ?az, Richard E. Newman, Ulrich Flegel, Elke Franz, Stefan Kopsell, Thomas Kriegelstein, Markus Kuhn, Stephen Lewis, Luc Longpre, Steven M- doch, Shishir Nagaraja, Thomas Nowey, Peter Palfrader, Lexi Pimenidis, Klaus Ploessl, Sivaramakrishnan Rajagopalan, Marc Rennhard, Leo Reyzin, Pankaj Rohatgi, Naouel Ben Salem, Sandra Steinbrecher, Mike Szydlo, Shabsi Wal?sh, Jie Wang, Brandon Wiley, and Shouhuai Xu.

Inhalt
Anonymity and Covert Channels in Simple Timed Mix-Firewalls.- Practical Traffic Analysis: Extending and Resisting Statistical Disclosure.- The Traffic Analysis of Continuous-Time Mixes.- Reputable Mix Networks.- Secure Outsourcing of Sequence Comparisons.- An Improved Construction for Universal Re-encryption.- Electromagnetic Eavesdropping Risks of Flat-Panel Displays.- On the Anonymity of Banknotes.- FLASCHE A Mechanism Providing Anonymity for Mobile Users.- Cryptographically Protected Prefixes for Location Privacy in IPv6.- Protecting User Data in Ubiquitous Computing: Towards Trustworthy Environments.- Synchronous Batching: From Cascades to Free Routes.- On Flow Correlation Attacks and Countermeasures in Mix Networks.- Measuring Anonymity in a Non-adaptive, Real-Time System.- Panel Discussion Mix Cascades Versus Peer-to-Peer: Is One Concept Superior?.- On the PET Workshop Panel Mix Cascades Versus Peer-to-Peer: Is One Concept Superior?.- A Formal Privacy System and Its Application to Location Based Services.- Privacy-Preserving Trust Negotiations.- Language-Based Enforcement of Privacy Policies.- Searching for Privacy: Design and Implementation of a P3P-Enabled Search Engine.- Contextualized Communication of Privacy Practices and Personalization Benefits: Impacts on Users' Data Sharing and Purchase Behavior.- Panel Discussion Conforming Technology to Policy: The Problems of Electronic Health Records.