Integrating Rivest–Shamir–Adleman (RSA) Encryption and Forward Error Correction (FEC) Codes for Secure and Robust Underwater Optical Wireless Communication

Abstract

Underwater Optical Wireless Communication (UOWC) offers a potential alternative to traditional Radio Frequency (RF) and acoustic methods, which suffer from low speed, short range, and high latency in underwater conditions. Reliability and security in UOWC are affected by signal degradation caused by turbidity, scattering, and absorption, which remain significant challenges. This study investigates a UOWC system by combining different modulation formats and Forward Error Correction (FEC) codes with Rivest-Shamir-Adleman (RSA) encryption and testing on a 4m in-house underwater channel. While FEC codes help reduce bit errors caused by the underwater channel, RSA encryption adds an additional layer of security by protecting the data from eavesdropping. The information is first encrypted and then processed through modulation and Forward Error Correction, if needed. The experimental results for the output file sizes of different modulation schemes and FEC codes aligned with theoretical expectations. For instance, the file size with repeat code (3) was three times the original; with repeat code (5), it was five times larger. OOK-RZ produced files twice as large as OOK-NRZ, while PPM resulted in a file size 16 times the original, and so on. Among the various FEC codes and modulation schemes employed, the results show that using Hamming, Bose–Chaudhuri–Hocquenghem (BCH), and Reed–Solomon codes improve system stability and security by nearly 1.5 times compared to using no FEC, particularly when integrated with PPM and DPIM modulation schemes. This approach offers a promising solution for applications in underwater robotics, environmental monitoring, and defence, demonstrating the potential of UOWC as a secure communication system for challenging and dynamic underwater conditions.