The key idea behind EV profiling is that each EV exhibits
unique physical characteristics during a charging session. More
precisely, when the State of Charge (SoC) of the battery
goes above a certain threshold (say, over 60% or 80%), the
current and voltage drawn by the vehicle solely depend on the
battery’s implementation. Therefore, these physical properties
- which can differ from one EV to another - can be used to
create signatures of EV batteries; consequently, the signature
of EVs. Authors in work [23] demonstrate modeling the
behavior of EV batteries from their charging data. Their work
extracts features from analog charging signals and uses that
information for battery profiling via clustering-based approach.
EVScout attack (originally EVScout1.0 [7], and recently EVS-
cout2.0 [6]) further improved such profiling of EVs by utilizing
different machine learning techniques.
Contributions: In this paper, we begin with improving the
state-of-the-art of EV profiling. To understand the impact of
the improved EV profiling approach at scale in the real world,
we emphasize on the multi-class classification (contrary to
binary classification considered in the state-of-the-art profiling
approach) to evaluate its efficacy in profiling/identifying a
particular EV. Furthermore, we consider datasets that vary in
size, balancing, and distribution to closely simulate different
settings. The major contributions of this paper are as follows:
1) We propose an improved EV profiling approach that
outperforms the state-of-the-art, i.e., EVScout.
2) We exhaustively evaluate the quality of our improved
approach at scale by considering a significantly large
dataset of charging sessions from real EVs as well as
different classification techniques, etc.
Organization: The remainder of this paper is organized as
follows. Section II presents a brief summary of the funda-
mental concepts related to our work. Section III explains our
threat model and attack infrastructure. Section IV elucidates
the implementation details of our approach. Section V reports
our experimental evaluations. Section VI comments on the
limitations of the current practices to profile EVs. Section VII
concludes the paper.
II. BACKGROUND
The concept of using electric or analog data for the
purpose of user profiling has been extensively studied in the
literature [11]. The central aspect of the EV charging system is
the EVSE infrastructure. A central control unit is responsible
for monitoring the operation of all EVSEs connected to a par-
ticular grid. These operations include appropriate scheduling
of charging processes (keeping track of power availability and
maximum allowed load for the network, etc.) and constituting a
gateway for secure communication between the grid and an EV
(to allow user authentication, etc.). It is important to note that
EVSEs are typically part of a complex network, where they can
communicate with each other, an EV, or the control unit via
appropriate communication interfaces. Such communications
happen over a secure channel that can be wireless or wired.
An EV user must be connected to the control center via a
car or mobile application. The security considerations of this
communication network is addressed by strong cryptographic
tools and mechanisms [13].
The physical port on EVSEs that connects it to an EV is
built upon SAE J1772 Standard [25] (cf. Fig. 1). According
to this standard, a port consists of five lead connectors. Out
of these five leads, three are are connected to the grid via
relays while the other two leads are used for signaling. In
particular, these two leads individually carry proximity signal
and pilot signal. The proximity signal verifies whether the
physical connection between the EV and EVSE’s port is safe
and that the communication or charging can proceed. On the
other hand, the pilot signal serves as a communication medium
between the EV and EVSE to signal charging level, etc.
The charging characteristics of the battery units used in
EVs also play a part in the profiling process. Most battery
units deployed in EVs today are lithium-ion batteries [9].
The charging process for standard lithium-ion batteries is
distinctive, where the drawn current and voltage follow a
fixed profile [20]. In particular, its charging process can be
of two types, i.e., Constant Power/Constant Voltage (CP/CV)
and Constant Current/Constant Voltage (CC/CV). In this work,
we only consider the latter as sufficient data is not publicly
available for CP/CV charging-based EVs. The CC/CV charg-
ing method consists of two phases:
1) Constant Current: It is the primary phase of charging,
during which the current passed remains constant while
the voltage across the battery terminals varies.
2) Constant Voltage: It is the latter phase of charging, during
which the current passed drops while the voltage across
the battery terminals remains constant.
The transition from the CC to CV phase is roughly preset,
but it is also ascribed by the state and condition of the
EV’s battery. Such transition threshold varies between 60%
and 80% of the battery’s SoC. Similar to the state-of-the-
art, our approach utilizes analog signal data (e.g., current
and pilot signals) obtained from the CC/CV charging phases
for EV profiling. Nonetheless, our work differs in various
aspects, including an improved profiling algorithm, modeling,
classification approach, etc.
III. THREAT MODEL
EV profiling attacks (e.g., EVScout [6, 7]) present in the
literature assume that an attacker is capable of installing a
physical device - typically over EVSEs’ physical port - to
intercept the analog signals exchanged between EVSEs and
EVs. With such a device in place, the attacker(s) can intercept,
record, or transmit the observed signals to the attacker(s),
where they can process the collected signals. It is worth
mentioning that if such a device has wireless transmission
capabilities, then tracing the original attacker(s) can become
even more difficult. By tampering multiple EVSEs, the at-
tacker(s) can have access to multiple charging sessions of
different (often, even the same) EVs. Therefore, the attacker(s)
can exploit such charging data to profile the unique charging
behavior of an EV’s battery; which essentially means the
profile of that EV.
The data obtained by such a data collection practice will be
unlabeled because the extracted signal is analog in nature and
does not contain any personally identifying details. Manual
monitoring, utilizing cameras, or collusion with local staff
can make the attack sophisticated. Nevertheless, by gathering
2