Secure Multi-User Contract Certificate Management for ISO 15118-20 Using Hardware Identities

In recent years, traditional mobility concepts have been increasingly transformed in favor of electric mobility and vehicle sharing concepts to combat pollutant emissions and inner-city traffic congestion. While the electric charging standard ISO 15118 with its Plug&Charge (PnC) concept eases the user experience by handling the complex billing process automatically during the charging, it is currently not suitable to the new multi-user mobility concepts since it does not define how to handle charging identities for multiple users per vehicle. With the Trusted Platform Module (TPM) 2.0 already part of the current ISO 15118-20 standard, we propose a new secure and standard-compliant multi-user contract certificate management system for ISO 15118-20 that utilizes the TPM in the vehicle as hardware trust anchor to handle multiple vehicle users. Our concept has little overhead to the current standard and introduces secure TPM-based multifactor authentication into ISO 15118-20, while maintaining the convenience benefits of PnC.