George Danezis: Cryptography in Anonymous Communications
Abstract
Anonymous communications have gained popularity both as a subject of
academic research as well as being deployed and used by thousands of
people. The protocols used hide who is communicating with
whom using a mixture of cryptographic techniques, to make the
content of the communication unlinkable, as well as traffic analysis
counter-measures to disrupt information observers may extract from
the timing and frequency of the traffic. This talk will present an
overview of the cryptographic techniques used in theoretical as well
as deployed mix and onion routing systems. The talk will be
illustrated by concrete attacks that allow attackers to violate anonymity
properties against hybrid cryptographic constructions as well as newer
constructions based on universal re-encryption. Finally the open problems,
of providing sound security definitions, as well as formal proofs for the
security of anonymity related cryptographic constructions will be presented.
Biography
George Danezis is post-doctoral visiting fellow at the Cosic group,
K.U.Leuven, in Flanders, Belgium. He has been researching anonymous
communications, privacy enhancing technologies, and traffic analysis for
the last 6 years, at K.U.Leuven and the University of Cambridge, where
he completed his doctoral dissertation.
His theoretical contributions to the PET field include the established
information theoretic metric for anonymity and the study of statistical
attacks against mix systems. On the practical side he is one of the lead
designers of Mixminion, the next generation remailer, and has worked on
the traffic analysis of deployed protocols such as SSL and Tor. He was
the co-chair of the Privacy Enhancing Technologies Workshop in 2005 and
2006, he serves on the PET workshop board and has participated in
multiple conference and workshop program committees in the privacy and
security field.