Dynamic charging is an emerging technology that
allows an electric vehicle (EV) to charge its battery while moving
along the road. Dynamic charging charges the EV’s battery
through magnetic induction between the receiving coils attached
to the EV’s battery and the wireless charging pads embedded
under the roadbed and operated by Pad Owners (POs). A key
challenge in dynamic charging is billing, which must consider
the fact that the charging service happens while the EV is
moving on the road, and should allow for flexible usage plans.
A promising candidate could be the subscription-based billing
model, in which an EV subscribes to an electric utility that has
a business relationship with various POs that operate charging
sections. The POs report charging information to the utility of
the EV, and at the end of each billing cycle, the EV receives a
single bill for all its dynamic charging sessions from the utility.
Overshadowing its advantages, a major shortcoming of such
a solution is that the utility gets access to the EVs’ mobility
information, invading thus the location privacy of the EVs.
To enable subscription based billing for dynamic charging, in
this paper we propose Janus, a privacy-preserving billing protocol
for dynamic EV charging. Janus uses homomorphic commitment
and blind signatures with attributes to construct a cryptographic
proof on the charging fee of each individual dynamic charging
session, and allows the utility to verify the correctness of the EV’s
total bill without learning the time, the location, or the charging
fee of each individual charging session of the EV. Our Pythonbased
implementation shows that the real-time computational
overhead of Janus is less than 0.6 seconds, which is well within
the delay constraint of the subscription-based billing model, and
makes Janus an appealing solution for future dynamic charging
applications.Department of Energy/DE-OE0000780Ope
