TSAF: Tamper-Resistant and Scalable Mutual Authentication Framework for Plug-in EV Charging

Aligned with the roll-out of plug-in Electric Vehicles (EV), a key area of research to enable high EV penetration is a secure and efficient charging system for EV batteries. In recent literature on EVs, reliable and cost-efficient grid operations under high EV penetrations assumes the need of EV charging load control. In this scenario EV charging (and discharging) must be adapted in real time to current grid constraints and sudden grid status changes. However, for realizing these load control functions, grids and EVs should trust each other before executing the operation. Whenever an EV is plugged into a grid for charging, it must be authenticated by the grid; otherwise, EVs and grids are open to security threats that could result in serious safety hazards and billing issues. In this paper, we first view the EV authentication problem as a mutual-authentication problem within a mobile and hostile machine-to-machine (M2M) communication setting. We describe a mutual authentication system tamper-resistant and scalable mutual authentication framework TSAF that can support large-scale grid-connected EV charging. The TSAF is based on two key notions, authentication token (AT) for stateless authentications and key obfuscation block (KoB) for protecting authentication key information of client devices. Note that the TSAF is the first proposed system that supports mobility, tamper-resistance, secrecy exposure resilience, low cost/complexity, and ease of management.