## 4 The SECOM Standard  
The increase in reliance on digital systems in the maritime domain has paved the way for a wide range of cyberattacks. These cyberattacks can lead to compromised operational security, potential disruptions to business operations, and data breaches. One key aspect in mitigating these concerns is the adoption of standardised procedures and protocols for secure data transmission and communication, such as the SECOM standard [2]. IEC 63173-2 SECOM is an international standard defining a secure communication protocol between a ship and an SCC, which provides capabilities for secure data exchange with  
Figure 2: The applications in the Shore Control Centre.  
technical services that are defined by IALA [22] and partly included in the IHO S-100 standard [23]. The standard includes information service interfaces (APIs) for the data exchange, and information security measures using a Public Key Infrastructure (PKI), covering communication channel security and data protection aspects. The exchange of messages between the ship and the SCC relies on IP-based web services.  
The SECOM components provide measures to meet the security requirements of the applications such as data authentication and integrity, service authentication and mutual TLS, data confidentiality and secure communication channels, access control, and identification through a common registry for unique identities.  
Due to the complexity of maritime networks, in addition to a secure communication protocol capability between the ship and SCC, there is a need for a framework that can properly address scalability as well as fault-tolerance-related aspects. Hence, the SECOM standard is implemented relying on a microservice architecture (namely MSA-based SECOM). The MSA-based SECOM is deployed on the SCC, and it comprises different microservices, as shown in Figure 3. Some are employed for non-functional requirements, such as the API Gateway, the discovery server, the authentication and authorisation server, the distributed tracing mechanism, and the message broker. Then, there is a suite of microservices that are required to implement the SECOM functionalities, such as the symmetric encryption and symmetric decryption, the asymmetric encryption and signature, the asymmetric decryption and signature verification, the key generator, and WebSocket. The main purpose of the SECOM standard is to enable the exchange of information that is consistent with the S-100 data model from the ship to the SCC and vice versa in such a way that the security requirements are fulfilled.  
As shown in Figure 4, the SECOM system architecture has three main blocks: the ship side, the MSA-based SECOM suite, and the SCC side. On the ship side, users are connected through a browser and can exploit the functionalities provided by the ship-side microservices. They are provided with a digital certificate and a private key to encrypt messages to be sent to the shore. The SCC operator also has his own certificate and a private key and can send encrypted messages to the ship side.  
To achieve the capability of exchanging messages, the ship sends an HTTP request to the API Gateway acting as a proxy. The gateway in turn redirects the request to the authentication server that has to authorise it. If the request is approved, it is redirected to the microservice that allows the ship to establish a WebSocket connection and make a  
Figure 3: Components of the SECOM architecture.  
digital copy of all the services on its side. At this point, the microservice starts to interact with the other microservices to finally provide the user with a shared key, enabling end-to-end encryption between the two entities. Having the shared key, the ship sends an encrypted and authenticated message to the SCC. Assuming the SCC has undergone the authentication step and has established a WebSocket connection, the SCC can receive the messages, verify that they arrived from the ship, and decrypt them using the shared key.