Roaming electric vehicle charging and billing: An anonymous multi-user protocol

In this paper, we propose a secure roaming electric vehicle (EV) charging protocol that helps preserve users´ privacy. During a charging session, a roaming EV user uses a pseudonym of the EV (known only to the user´s contracted supplier) which is anonymously signed by the user´s private key. This protocol protects the user´s identity privacy from other suppliers as well as the user´s privacy of location from its own supplier. Further, it allows the user´s contracted supplier to authenticate the EV and the user. Using two-factor authentication approach a multiuser EV charging is supported and different legitimate EV users (e.g. family members) can be held accountable for their charging sessions. With each charging session, the EV uses a different pseudonym which prevents adversaries from linking the different charging sessions of the EV. On an application level, our protocol supports fair user billing, i.e. each user pays only for his/her own energy consumption, and an open EV marketplace in which EV users can safely choose among different remote host suppliers.