## 7 Conclusions and Future Work  
In this paper, we addressed the security challenges related to the maritime domain by implementing the SECOM standard for securing the communication channel between the ship and the Shore Control Centre and by testing the machine learning algorithms for anomaly detection on the ICT reference stack of the Port of Livorno. The proposed implementation of the SECOM standard uses a secure and scalable microservice architecture and provides data and service authentication, confidentiality, integrity, identification, and non-repudiation. Confidentiality was achieved as the shared key was only known to the parties involved in the encryption step (ship and SCC). This property is guaranteed since each public key is signed by the sender and encrypted with the receiver's certificate. Hence, it will be difficult for the parties not involved in the communication to intercept the shared key, unless they have the private key of both sides. In addition, messages cannot be repudiated, as we can verify that the message encrypted and sent over the channel came from the entity that holds the same shared key as the receiver. Data integrity and authentication were also guaranteed as the message is encrypted using AES with GCM mode and so has a tag attached to it that can be generated only by the  
Figure 12: HD-DNCAE (Adadelta) AUC score table. Figure 13: Performance comparison of DNCAE, HD-DNCAE (SGD with momentum), and HD-DNCAE (Adadelta). key pair holders. On top of this, the implementation of a mutual authentication procedure for the authentication among the microservices provides service authentication property. Moreover, the scalability and robustness of our system addresses security challenges faced in the communication relying on the IHO S-100 [23] compliant messages. Scalability and robustness enable improved fault tolerance and better performance and efficiency for services in case of high traffic loads and multiple requests. Finally, the identification was achieved as each service consumer needs to be authenticated with the pre-registered credentials using only valid access and JWT tokens. Hence, the implementation of the SECOM standard based on a microservice architecture addresses the security challenges existing in the maritime sector and traditional monolithic applications. On one side, our implementation provides a mutual authentication procedure to guarantee service authentication among microservices. On the other side, it provides the capability to generate and share keys among the parties (e.g., ship and the SCC) so that the information travelling through untrusted public networks can be exchanged securely. The future direction of the proposed implementation of the SECOM standard involves orchestrating microservices using advanced tools like Kubernetes. This approach aims to improve system resilience, fault tolerance, and scalability, especially under heavy network traffic or system failure conditions. Additionally, integrating a centralised log-tracing system and automated configuration management is recommended. These enhancements will streamline monitoring, facilitate quicker troubleshooting, and simplify environment variable management, making the system more reliable and easier to maintain. Furthermore, this paper introduced HD-DNCAE, an enhancement to the DNCAE model, implemented with SGD momentum and Adadelta optimisers. We repeated the experiments across multiple datasets to demonstrate HD-DNCAE's performance in anomaly detection tasks. On the NSL-KDD dataset [40], HD-DNCAE (SGD momentum) with KDE and CEN classifiers achieved an AUC of 0.955, as with DNCAE's performance. For the UNSW-NB15 dataset [41], HD-DNCAE (SGD momentum) with LOF reached 0.831 AUC, outperforming DNCAE's 0.542. Moreover, HD-DNCAE showed improvements in several CIC-IDS [42] scenarios:  
* Tuesday: HD-DNCAE (Adadelta) with LOF achieved an AUC of 0.935 against 0.476 with DNCAE. * Wednesday: HD-DNCAE (Adadelta) with OCSVM (linear and poly) maintained an AUC of 0.717, while DNCAE obtained 0.398.