Computer Science Graduate Seminar: Stefan Wüller: Privacy-Preserving Electronic Bartering

Wednesday, 21.02.2018, 9:00am

Location: UMIC Research Centre, RWTH Aachen University, room 024


Speaker: Stefan Wüller  (Research Group IT-Security)


E-commerce applications like online shopping, e-marketplaces, and e-banking are becoming more and more prevalent in our daily lives. While providing a lot of convenience, these applications generally require the divulgence of sensitive personal data. Typically, it is not transparent for their users what the personal data are used for. A majority of users may be willing to share sensitive personal data on the Internet to some extent when there is a balance between the involved benefits and drawbacks. However, this is certainly not the case if those data, for instance, one's room for negotiation, have the potential to adversely affect e-commerce transactions which can occur particularly in the context of online bartering marketplaces. The research goal of this thesis is to advance the privacy-protection of online bartering marketplaces such that users do not have to disclose sensitive private data-including their offers/demands as well as the quantities thereof-to anyone in order to find suitable trade partners. Our approach is to design privacy-preserving protocols that can be used as a key component of a bartering system allowing its users to barter their commodities in a privacy-preserving fashion. More precisely, we devise a novel privacy-preserving bartering protocol for the two-party case providing security against active adversaries as well as two novel privacy-preserving bartering protocols for the multi-party case which provide security against passive and active adversaries, respectively. The focus of this thesis is on the much more complicated multi-party case which, compared to the two-party case, requires completely new design approaches as well as the development of novel privacy-preserving building blocks for comparison and selection operations that are of general interest beyond the context of bartering. Using our privacy-preserving multi-party bartering protocols-practical for a limited number of parties-as a key component, we model a bartering system that allows an arbitrary number of parties, arriving at the system over time, to barter their commodities in a privacy-preserving fashion. The implementation and the simulation of our novel privacy-preserving bartering model as well as the comparison to the most prominent conventional bartering models show that the modeled privacy-preserving bartering system is practical.