An efficient privacy-preserving pay-by-phone system for regulated parking areas

Traditional pay-and-display ticket machines are currently coexisting, but will probably be replaced in the near future, with pay-by-phone applications. Such applications facilitate the payment for parking in regulated areas. Companies providing this service collect and manage information about all the parking transactions performed by drivers. That information is very sensitive and can be used to generate reports on the parking history of drivers, posing a threat on their privacy. This paper proposes a pay-by-phone parking system in which the service provider is prevented from being able to track the parking transactions of drivers. The new proposal requires drivers to be connected only at the beginning of a parking transaction, or at the moment of indicating that a parking transaction took less time than expected. Prototype experiments have shown that the new proposal is much more efficient, in terms of computational cost, than the most complete previous existing system, while providing the same functionalities and higher security.