SlotSwap: Strong and Affordable Location Privacy in Intelligent Transportation Systems

Public acceptance, and thus the economic success, of an ITS is highly dependent on the quality of deployed privacy mechanisms. In general, neither users nor operators should be able to track a given individual. One approach to facilitate this is the usage of pseudonym pools, which allow vehicles to autonomously switch between different identities. We extend this scheme with that of a time-slotted pseudonym pool of static size, reducing the storage and computation needs of the envisioned ITS while further improving users' privacy. In addition, we allow the exchange of pseudonyms between vehicles, eliminating the mapping between vehicles and pseudonyms even for the ITS operator. We support the exchange of both current and future pseudonyms, further enhancing users' privacy. We evaluate the feasibility of our approach and back up privacy claims by performing a simulative study of the system using the entropy of nodes' anonymity sets as the primary metric.