Polarization Fingerprint: A Novel Physical-Layer Authentication in Wireless IoT

Radio frequency (RF) fingerprinting is a low-cost, high-efficiency, and high-security authentication technique for wireless IoT devices with limited resources, but RF fingerprinting faces problems such as small fingerprint differences, low finger-print stability, and high implementation difficulty. In order to solve these problems, we propose a novel concept of polarization fingerprinting. Polarization fingerprint (PF) is manifested as the correlation between polarization state and frequency. The properties of PF include group feature, individual feature and directionality. Group feature characterizes the antenna structure, and individual feature characterizes the antenna hardware imperfections. The directionality comes from the vector property of polarization and contains the relative position information of the communicating devices. The directionality solves the problem of similar fingerprints that may occur when the number of devices increases, which cannot be solved by RF fingerprinting. Compared to RF fingerprint, PF can exist stably and continuously, which not only solves the problem of low fingerprint stability, but also makes polarization fingerprinting based authentication easier to be implemented. The stability and continuity of PF allow more samples to be obtained during authentication. We also proved that increasing the sample amount can reduce the false alarm rate of authentication. Finally, we conducted experiments based on wireless IoT devices. Experiment results show that polarization fingerprinting based authentication has better performance than RF fingerprinting based under the same conditions.