Pixy: A Privacy-Increasing Group Creation Scheme
David Mödinger, Nicola Fröhlich, Franz J. Hauck · 2020
Modern peer-to-peer networks provide a lot of value. However, as the networks handle more and more sensitive data, e.g. in cryptocurrencies, privacy becomes an issue. Several approaches to provide efficient privacy to network participants rely on group formation with little or no regard to the privacy impact of how groups are created. Group creation is often based on random selection, which can easily be highjacked by attackers. We propose Pixy, an extensible, component-based scheme to increase privacy during group formation stages beyond current approaches. Our scheme provides a two-stage setup for group formation. First, a selection based on personal and network-wide collaboration lists reduces the attack surface for group initiators. Second, a testing phase based on cryptographic puzzles and, for suitable contexts, CAPTCHAs sort out Sybil attackers. We show that this scheme improves the current state of privacy in group-creation processes.