Researchers have demonstrated for the first time the possibility of identifying and tracking a smartphone user based on a Bluetooth signal. The technology allows you to identify almost 50% of unique devices.
Due to manufacturing defects in the equipment, the Bluetooth signal of a particular device has a unique “fingerprint”. In a paper presented at the IEEE Security & Privacy conference, engineers from the University of California, San Diego showed that this feature can be used to identify and track a specific smartphone.
The researchers explain that all wireless devices have small, unique manufacturing hardware defects. This is a side effect of the manufacturing process. Imperfections of the equipment lead to unique signal distortions that can be used as “fingerprints” of a smartphone.
Previous studies have shown that such a trace forms a Wi-Fi signal. A long sequence called a preamble is used to identify it. Such a method, as the authors of the work note, is not suitable for identifying a Bluetooth signal: his preamble is too short.
Instead, the researchers have developed a new method that analyzes the entire Bluetooth signal. The created algorithm uses two signal parameters: carrier frequency offset and I/Q signal offset. As a result, the program determines the device with high accuracy.
This is important because in today’s world, Bluetooth is a more serious threat than Wi-Fi, as it is a popular and continuous wireless signal emitted by all our personal mobile devices.
Nishant Bhaskar, co-author of the study
In a series of experiments, the programmers tested their tracking method. Using the algorithm, the researchers uniquely identified 47% of the 647 mobile devices of visitors to the public corridor on the university campus. After that, the developers arranged a real “surveillance”: sensors installed near the doors recorded information about the time of arrival and departure of a volunteer from home.
Now, scientists are working on a technology that will hide Bluetooth “fingerprints” using digital signal processing in the firmware of the device.