Dynamic Key Update Strategy in Physical-Layer Challenge-Response Authentication

Physical layer (PHY) authentication based on the unique channel properties has attracted attention due to its simple, fast, and distributed procedures with the recent explosion of the Internet of things (IoT) devices. In this paper, we propose a novel PHY challenge-response authentication mechanism (PHY-CRAM) with a dynamic key update strategy for the potential application of massive IoT connections. Conventional PHY-CRAM is fully insecure once the key is exposed to a malicious intruder, whereas the proposed scheme automatically updates the secret key for the next channel use based on the current channel gains. In this way, the following impersonation attacks using the previously exposed secret key become nearly useless. Furthermore, the intruder is hard to estimate the updated key because the physical channel typically changes quickly over time. Through multi-carrier transmission simulations, the proposed scheme is evaluated by authentication performance (e.g., receiver operating curve (ROC)), compared to the conventional PHY-CRAM. The results show that the proposed scheme has a better authentication performance, compared to the conventional scheme under the secret key leakage scenario. In the situation where the authentication key is 80% leaked, the SNR is 6dB, and the detection probability is 0.99999, the conventional method has a false alarm probability of 0.8785 while the proposed method has a good performance of 0.0397.