## 1 Introduction
To fully understand this, we consider the following three points in the MASS system: (1) there will be no voice command or control loop (i.e., VHF) between maritime administrations and autonomous ships, and maritime regulation must be achieved through digital means; (2) autonomous ships will have a shoreside remote control center, which makes the structure of digital maritime administrations less flat; and (3) in a highly digital maritime management scenario, interactions between entities of maritime participants require authenticated identification and communication, thus requiring more sophisticated technology. These fundamental changes mean that security issues in this era include not only the traditional operational aspects of maritime incidents but also cyber security challenges. In traditional maritime day-to-day practice, voice-based communications dominate, and one usually does not need to question the authenticity of calls and answers over public channels. However, in the MASS scenario, the aforementioned issues call for careful handling of malicious entities. To make things concrete, a realistic approach is to resort to traditional information security solutions. In theory [14], asymmetric encryption and digital certificate technologies already provide a solid foundation for identification, authentication, tamper-proof verification, and, if necessary, confidentiality. However, the practical implementation of traditional information security approaches has proven challenging in real-world maritime environments [15]. First, the connectivity of the MASS entity network is highly dynamic and unstable. This means that any approach based on asymmetric encryption has to be implemented opportunistically and should take additional considerations compared to its implementation in a reliable network infrastructure (e.g., the internet). Second, due to the high mobility of navigational data exchange, there are no clear boundaries to define data bulk sessions or transactions between entities. At the same time, the data records exchanged on the network are large and increasing in number, and these data are not assigned to specific nodes for storage in the MASS network. As a result, data collection is performed in a peer-to-peer manner, which requires a fast and reliable way to manage the trustworthiness of data distribution. This challenge reveals two research questions: (1) What is the relationship between traditional information security and trust management? (2) How do we introduce new approaches and technologies when traditional information security is no longer applicable to future MASS scenarios? In view of the above, this paper aims to develop a blockchain-based approach for trust management among participants in MASS systems to ensure their cybersecurity. Effective communication between encountering ships has been identified as an important issue and one of the main obstacles affecting the outcome of ship CA. In this paper, we aim to develop a blockchain-based solution for trusted communication in ship encounter avoidance by investigating the fundamental trust issues in the cybersecurity aspects of the ship encounter avoidance process. The innovative concept of using blockchain in the context of ship CA decision-making is that the various participating ships in a dynamically changing ship encounter scenario constitute a decentralized network of opportunities, which makes blockchain an attractive tool to provide a solution for assessing and maximizing trust in entity dynamics. In this paper, we describe the mechanism of entity participation in maintaining a master chain for ship encounter avoidance. First, the paper analyzes traditional ship CA decision scenarios to find formal communication methods that can simplify information. Based on this, it is illustrated how beliefs of trust (BoT) between entities that first meet during ship CA are encoded and combined on the chain to allow entities in the encounter scenario to have an initial judgment about another entity before they become familiar with it.