Artificially Time-Varying Differential MIMO for Achieving Practical Physical Layer Security

Abstract

In this paper, we propose a differential multiple-input multiple-output (MIMO) scheme based on the novel concept of chaos-based time-varying unitary matrices to demonstrate-for the first time in the literature-the ability of differential encoding in achieving practical physical layer security even without the need for using channel estimation. In the proposed scheme, an erroneous secret key, which is extracted from the wireless nature, is used to initialize a chaos sequence that is responsible for generating artificially time-varying unitary matrices capable of obfuscating the transmitted data symbols from illegitimate eavesdroppers. Contrary to conventional studies, the key agreement ratio in this study is assumed to be imperfect, which is often true and very realistic in high-mobility scenarios. Following this, we conceive a new calibration algorithm for reconciling the chaotic sequence generated at the legitimate parties, thus making this calibration algorithm a unique, novel solution to the key sharing problem of conventional chaos-based communication techniques, which has been overlooked over the past few decades. It is found out that differential encoding obviates additional complexity and insecurity in dealing with channel estimation, whereas an eavesdropper must tackle the complicated differentially encoded patterns, which have an exponentially increasing complexity order. In addition, the obtained simulation results demonstrate that the proposed scheme can outperform conventional chaos-based MIMO schemes that assume perfect channel knowledge.

Noncoherent Massive MIMO with Embedded One-Way Function Physical Layer Security

“…Our first assessment, depicted in Fig. 8, is the information leakage [11] to Eve, measured as 1 − 2 × BER Eve , with BER Eve given by the average bits in error in the symbols X(i) detected by Eve under equation (40), using projection matrices Ê1 estimated by solving equation (39), and given received signals ỸEve obtained in the absence of noice, as described by equation (37). The figure shows plots of such leakage as a function of the number of transmit antennas M , varied from M = 2 to 128, and for different configurations receive antennas at Eve, varying from N Eve = 2 to N Eve = 16.…”

“…In light of the above, the main idea of PLS is to exploit physical features of wireless channels [7][8][9][10][11], to design quantum resilient, and eventually quantum-proof (a.k.a postquantum) security solutions. To cite a few examples, in [7], the randomness of extracted channel state information (CSI) in massive MIMO systems is used to construct linear precoding matrices that provide post-quantum security via large-scale beamforming and large constellation sizes.…”

Secure authentication in MIMO systems: exploring physical limits

“…A MIMO scheme for practical physical-layer security was presented by Ishikawa et al (2021). It employs chaos-based unitary matrices to eliminate the need for channel estimation.…”

Noncoherent Massive MIMO With Embedded One-Way Function Physical Layer Security

“…In light of the above, the main idea of PLS is to exploit physical features of wireless channels [7], [8], [9], [10], [11], to design quantum resilient, and eventually quantum-proof (a.k.a post-quantum) security solutions. To cite a few examples, in [7], the randomness of extracted channel state information (CSI) in massive MIMO systems is used to construct linear precoding matrices that provide post-quantum security via large-scale beamforming and large constellation sizes.…”

“…Similarly, in [8], security is incorporated into STBC schemes by translating random received signal strength indicators into phase rotations of transmit symbols, while in [9], the reciprocal phase of the channel between Alice and Bob is used as a seed for the legitimate pair to select the modulation they employed. In turn, in the chaos-based approaches of [10] and [11], a secret key is projected onto a space-time codeword and onto a time-varying unitary matrix, respectively.…”