Private Metering in EV Charging Infrastructure: An OCPP Extension

The security of electrical vehicle (EV) charging systems has been improving over the past years. However, privacy concerns are yet to be addressed as profiling attacks can be accomplished on EV charging meter readings. This paper proposes a new communication protocol that preserves the privacy of users while retaining the aggregate metering values to be used by the EV charging management system. The proposed protocol extends the existing Open Charge Point Protocol (OCPP) specifications. OCPP is an open and widely used protocol for EV chargers but it provides no privacy-preserving mechanisms. Differential privacy concepts are applied in the proposed paper along with key masking to hide private data from different kinds of adversaries. A lightweight implementation of the proposed approach is implemented and tested on a hardware testbed to ensure the practicality of the implemented system. Experimental results and analysis show that this method is able to preserve the confidentiality of metering values with minimal computation.