Security enhancement for OFDM-UWOC system using three-layer chaotic encryption and chaotic DFT precoding

Abstract

Security is one of the key issues in communications, but it has not attracted much attention in the field of underwater wireless optical communication (UWOC). This Letter proposes a UWOC encryption scheme with orthogonal frequency division multiplexing (OFDM) modulation, based on the three-layer chaotic encryption and chaotic discrete Fourier transform (DFT) precoding. The three-layer chaotic encryption processes are bit stream diffusion, in-phase/quadrature encryption, and time-frequency scrambling. With multi-fold data encryption, the scheme can create a keyspace of 9.7 × 10 179 , effectively resisting brute force attacks and chosen-plaintext attacks. A 3 Gbit/s encrypted OFDM signal is successfully transmitted over a 7 m water channel.

High Speed Dual‐Band Photodetector for Dual‐Channel Optical Communications in Wavelength Division Multiplexing and Security Enhancement

“…The correct decoded information is obtained by modulating the operating mode of the receiver with a bias voltage according to the key, adding/subtracting the visible and NIR light signals or solely receive one of them. The execution of arithmetic operations has enabled the coupling of optical signals from two independent channels, significantly enhancing encrypted communication security compared to previous work 28 . Because the signals are coupled through optical power ratios and arithmetic relations, eavesdroppers could not record the two signals separately and decipher them by trying different key combinations.…”

“…[21,22] Quantum key distribution (QKD) implements a cryptographic protocol involving quantum mechanics to ensure security, but typically supports an extremely low data rate of <5 kbps for single source in short-reach access. [23,24] Besides, some other encryption algorithms, such as the phase deflection, [25] the higher-order modulated stream, [26] and multi-layer chaotic encryption [27,28] have been proposed to encrypt data in OWC, respectively. The early-stage encryption schemes suffer from a low encryption dimension and a small key space, while the multi-layer chaotic encryption involves complicated structure and massive computation.…”

Security enhanced underwater visible light communication system based on chaotic phase scrambling and conjugate frequency hopping

“…In 2021, Zhejiang University first verified the feasibility of chaotic encryption in high-speed UVLC systems [10] , using two-dimensional encryption at the bit and subcarrier levels and verified that chaotic encryption has no negative impact on the performance of the system. In 2022, they also used bitstream diffusion, in-phase and quadrature components scrambling, and time and frequency scrambling for three-dimensional encryption of UVLC systems [11] . However, all these encryption algorithms are complex in implementation and have high requirements for system performance.…”