Physical Layer Secret Key Generation Using Joint Interference and Phase Shift Keying Modulation

In existing physical layer security (PLS) and key generation protocols, major assumptions, including channel reciprocity, localization, and synchronization between the legitimate parties, are often considered. However, these assumptions are arguable in practice leading to major barriers in building systems based on PLS protocols. To overcome these barriers, we proposed, designed, and implemented a novel embedded architecture for distributed Internet-of-Things (IoT) networks that utilize a master-slave full-duplex communication to exchange a random secret key. In the proposed architecture, an IoT node generates a phase-modulated random key/data and transmits it to a master node in the presence of an eavesdropper, referred to as Eve. The master node, simultaneously, broadcasts a high-power signal using an omnidirectional antenna, which is received as a jammer signal or interference by Eve. This results in a high bit error rate (BER) making the data undetectable by Eve. The two legitimate nodes communicate in a full-duplex fashion and, consequently, subtract their transmitted signals from the received signal (self-interference cancellation). Our proposed protocol does not require any knowledge of the node locations. In particular, we show, using theoretical and measurement results, that our proposed approach provides significantly better security measures, in terms of the BER at Eve's location, compared to a conventional method based on directional beamforming antennas. Also, it is proved that in our novel system, the possible eavesdropping region, BER <; 10
^-1
, is always smaller than the reliable communication region, BER <; 10
^-3
.