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 assume 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 proposed TSAF is based on two key notions, authentication token (AT) for stateless1 authentications and key obfuscation block (KoB) for protecting authentication key information of client devices. Note that TSAF is the first proposal that addresses mobility, tamper-resistance, key exposure resilience, low complexity, and ease of management for plug-in EV charging.