## 6 UOWC Security Concerns and Challenges and Future Directions  
### UOWC Security Concerns  
Security concerns in UOWC systems are an emerging area of research due to the increasing reliance on underwater communication for applications such as marine exploration, military operations, and environmental monitoring. The security challenges in UOWC systems stem from the unique underwater environment, resource constraints, and reliance on optical properties. Addressing these concerns requires interdisciplinary approaches, integrating insights from physical optics, communication theory, cryptography, and machine learning. Emphasising energy efficiency, robustness, and real-time adaptability will be critical for advancing security in UOWC systems. Table 10 summarises key research directions and challenges related to security in UOWC systems.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**Research Direction**} & \multicolumn{2}{c}{**Challenges**} & \multicolumn{1}{c}{**Ref.**} \\ \hline
**1. Physical Layer Security** & \(\bullet\) & **Exploitation of Channel Characteristics:** & \(\bullet\) & High variability in underwater channels (e.g., \\  & & & & due to turbulence and \\  & & & enhance security. This could include & \\  & & techniques like secure beamforming and & & physical layer security \\  & & artificial noise injection. & & implementation difficult. \\  & & & & The limited communication \\  & & & methods for secure information exchange & \\  & & & without shared keys, using unique channel & \\  & & & properties. & \\ \hline
**2. Encryption and Authentication** & \(\bullet\) & Develop lightweight cryptographic algorithms & \(\bullet\) & Energy efficiency is critical \\  & & & suitable for low-latency, energy-constrained & \\  & & & underwater devices. & \\  & & & Implement authentication protocols that can & \(\bullet\) & Balancing computational \\  & & & handle dynamic underwater environments. & \\  & & & & data transmission \\  & & & requirements. & \\ \hline
**3. Eavesdropping** & \(\bullet\) & Model and simulate eavesdropping scenarios & \(\bullet\) & The high directivity of \\  & & in UOWC systems, including how underwater & & UOWC beams limits \\  & & scattering and attenuation affect an adversary’s & & eavesdropping and makes \\  & & ability to intercept communications. & & secure beam alignment \\  & & & Implement directional communication and & \\  & & spatial filtering techniques to minimise & \(\bullet\) & Potential for signal leakage \\  & & eavesdropping risk. & & in multi-hop UOWC \\  & & & & networks. \\ \hline
**4. Jamming and Denial of** & \(\bullet\) & Develop techniques to detect and mitigate & & \\  & & jamming attacks, including dynamic frequency & & \\  & & hopping and adaptive power control. & & \\  & & & & natural channel \\  & & & & impairments. \\  & & & denial of service attacks, such as exploiting & \\  & & high-scattering regions. & & \\  & & & & \\  & & & & \\ \hline
**5. Data Integrity and Packet** & \(\bullet\) & Design error detection and correction schemes & \(\bullet\) & Ensuring data integrity over \\  & & to ensure data integrity over noisy UOWC & & long-distance, \\  & & channels. & & high-attenuation channels. \\  & & & & \\ Security & & Implement secure protocols for packet & \(\bullet\) & Synchronisation issues in \\  & & verification in multi-node underwater & & dynamic underwater \\  & & & environments. \\ \hline \hline \end{tabular}
\end{table}
Table 10: Security concern research directions and challenges.