## 6 UOWC Security Concerns and Challenges and Future Directions
### Challenges and Future Directions
\begin{table}
\begin{tabular}{c c c c c} \hline  & & **Research Direction** & **Challenges** & **Ref.** \\ \hline \multirow{4}{*}{6. **Key Distribution and Management**} & \multirow{4}{*}{\(\bullet\)} & Explore quantum key distribution through & \multirow{4}{*}{\(\bullet\)} & Implementing quantum key & \multirow{4}{*}{\(\bullet\)} \\  & & UOWC for secure key exchange. & & distribution in a highly & \multirow{4}{*}{\(\bullet\)} \\  & & Investigate underwater key management & & medium. & \\  & & protocols that leverage mobility and ad hoc & & \multirow{4}{*}{\(\bullet\)} & Synchronisation and latency \\  & & networking. & & issues in dynamic & \\  & & & underwater networks. & \\ \hline \multirow{4}{*}{7. **Interference from Environmental Factors**} & \multirow{4}{*}{\(\bullet\)} & Develop adaptive security mechanisms to address environmental interference, such as bioluminescence and turbidity. & \multirow{4}{*}{\(\bullet\)} & Real-time adaptation to highly variable & \multirow{4}{*}{\(\bullet\)} \\  & & Use machine learning to predict and adapt to environmental changes that may impact security. & & & \\  & & & & interference and malicious & \\ \hline \multirow{4}{*}{8. **Multi-Modal Communication and Integration**} & \multirow{4}{*}{\(\bullet\)} & Secure hybrid communication systems combining acoustic, optical, and radio frequencies. & \multirow{4}{*}{\(\bullet\)} & Synchronisation and secure & \multirow{4}{*}{\(\bullet\)} \\  & & Investigate vulnerabilities unique to modalities. & & multiple communication & \\  & & multi-modal systems, such as cross-medium attacks. & & & \\ \hline \multirow{4}{*}{9. **Resource Constraints**} & \multirow{4}{*}{\(\bullet\)} & \multirow{4}{*}{Develop energy-efficient security mechanisms tailored for resource-constrained underwater devices.} & \multirow{4}{*}{\(\bullet\)} & Limited computational resources of underwater & \multirow{4}{*}{\(\bullet\)} \\  & & & devices restrict the & & \\ \cline{1-1}  & & Optimise trade-offs between security, power consumption, and communication performance. & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \hline \multirow{4}{*}{10. **Secure Network Protocols for UOWC**} & \multirow{4}{*}{\(\bullet\)} & Design underwater-specific secure routing and media access protocol layer protocols. & \multirow{4}{*}{\(\bullet\)} & Dynamic topology and mobility of underwater nodes complicate protocol design. & \multirow{4}{*}{\(\bullet\)} \\  & & packet duplication, and misdirection in underwater networks. & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & & \\ \hline \end{tabular}
\end{table} 
Table 10: _Cont._inhomogeneity caused by the change in chlorophyll contents, salt content, temperature, and ocean turbulence with depth when modelling the UOWC channel for all water types and communication link systems to improve its performance. Although we have not discussed the effects of turbulence, scintillation, and background scattering throughout the simulation investigations, in Section 2.2, we did indicate that, eventually, they will contribute to distorting the shape of \(h_{opt}(t)\) and causing an extension to the trailing ends (Figure 17). Such impact eventually contributes to the creation of ISI. Hence, it is more factual to model scintillation and turbulence contributing to the overall elastic scattering. Therefore, the simulation platforms must be expanded to account for these effects and investigate the combination of absorption, scattering, turbulence effects, reflection, background scattering effects, and all other IOP and AOP in underwater channels simultaneously. Many, if not all, MCS studies discussed the manifested extension of the tail profile of the received photons. These studies considered one optical pulse in their research.