Who is Charging My Phone? Identifying Wireless Chargers via Fingerprinting

Abstract

With the increasing popularity of the Internet-of-Things (IoT) devices, the demand for fast and convenient battery charging services grows rapidly. Wireless charging is a promising technology for such a purpose and its usage has become ubiquitous. However, the close distance between the charger and the device being charged not only makes proximity-based and near-field communication attacks possible but also introduces a new type of vulnerabilities. In this article, we propose to create fingerprints for wireless chargers based on the intrinsic nonlinear distortion effects of the underlying charging circuit. Using such fingerprints, we design the WirelessID system to detect potential short-range malicious wireless charging attacks. WirelessID collects signals in the standby state of the charging process and sends them to a trusted server, which can extract the fingerprint and then identify the charger. We conduct experiments on eight commercial chargers over a period of five months and collect 8000 traces of signal. We use 10% of the traces as the training data set and the rest for testing. The results show that on the standard performance metrics, we have achieved 99.0% precision, 98.9% recall, and 98.9% $F1$ -score.