  Dynamic wireless power transfer provides means for charging Electric Vehicles
(EVs) while driving, avoiding stopping for charging and hence fostering their
widespread adoption. Researchers devoted much effort over the last decade to
provide a reliable infrastructure for potential users to improve comfort and
time management. Due to the severe security and performance system
requirements, the different scheme proposed in last years lack of a unified
protocol involving the modern architecture model with merged authentication and
billing processes. Furthermore, they require the continuous interaction of the
trusted entity during the process, increasing the delay for the communication
and reducing security due to the large number of message exchanges. In this
paper, we propose a secure, computationally lightweight, unified protocol for
fast authentication and billing that provides on-demand dynamic charging to
comprehensively deal with all the computational and security constraints. The
protocol employs an ID-based public encryption scheme to manage mutual
authentication and pseudonyms to preserve the user's identity across multiple
charging processes. Compared to state-of-the-art authentication protocols, our
proposal overcomes the problem of overwhelming interactions and provides public
scheme security against the use of simple operations in wide open
communications without impacting on performance.
