Secure and privacy-preserving lightweight access control system for low emission zones

Low Emission Zones (LEZs) are urban areas in which the access of polluting vehicles is controlled with the objective of improving the air quality. This traffic control method has been already deployed in important cities such as London or Singapore, and several others are planning to implement them in the mid-term. While the current LEZ solutions have proven to be feasible, they have also turned out to require costly infrastructures such as expensive road side units and vehicle equipment. Moreover, their intrusive nature has raised social alarms regarding the potential violation of the drivers' privacy that their use may represent. To address these issues, this paper presents an access control system for LEZs specially designed to provide effective anti-fraud measures while preserving the privacy of the drivers who behave honestly. The new scheme is lightweight enough to be used in low-cost infrastructures. Moreover, the only equipment required at the driver's side is a common smartphone enabled with typical communication capabilities. One of the cornerstones of the proposal is its deployability in real scenarios, for this reason, the feasibility of the new technology is validated in a relevant environment and an extensive evaluation is provided.