This book constitutes the refereed proceedings of the 9th International Symposium on Privacy Enhancing Technologies, PETS 2009, held in Seattle, WA, USA, in August 2009.

The 14 revised full papers presented were carefully reviewed and selected from 44 initial submissions. The papers - both from academia and industry - cover design and realization of privacy services for the internet and other communication networks and present novel research on all theoretical and practical aspects of privacy technologies, as well as experimental studies of fielded systems.

The 8thPrivacyEnhancing TechnologiesSymposium washeldat the Katholieke Universiteit Leuven during July 23-25,2008.This year completed the transition from workshop to symposium, with a printed proceedings published before the symposium. PETS remains a premier venue for publishing original research on privacy-enhancing technologies. PETS received 48 submissions, each of which wasreviewedbyatleastfourmembersoftheProgramCommittee.Thirteenwere accepted into the program, maintaining the selective and competitive nature of the event. The program also included a keynote address by Stuart Shapiro. A new feature this year was the HotPETs session, designed to balance the desire for rigorous scienti?c quality of the PETS program and the need for a venue to present work that is not yet fully developed. HotPETs accepted s- missions on the hottest, most exciting new ideas and put together an excellent program of presentations. PETS was once again collocated with the IAVoSS Workshop on Trustworthy Elections (WOTE 2008), with a full day of plenary sessions. In addition, three otherprivacy-relatedeventswereheldatK.U.Leuvenduring thesameweek, - abling greater exchange of ideas among the respective communities: the closing event of the Privacy and Identity Management for Europe (PRIME) project, a workshop presenting the results from the Advanced Applications for Electronic Identity Cards (ADAPID) project, and a working session of the Future of Id- tity in the Information Society (FIDIS) Workpackage 13

This book constitutes the thoroughly refereed post-conference proceedings of the 23rd International Conference on Financial Cryptography and Data Security, FC 2019, held in St. Kitts, St. Kitts and Nevis in February 2019.The 32 revised full papers and 7 short papers were carefully selected and reviewed from 179 submissions. The papers are grouped in the following topical sections: Cryptocurrency Cryptanalysis, Measurement, Payment Protocol Security, Multiparty Protocols, Off-Chain Mechanisms, Fraud Detection, Game Theory, IoT Security and much more.