## 4 Results: State-of-the-Art Approaches
### Cybersecurity in IoUT  
From health to military industries, the race of achieving the most and most valuable information is challenging. Especially in military operations, information is the key factor which will determine the successful outcome. However, special components of information should be considered, namely the CIA triad as mentioned above. Underwater assets rely strongly on ICTs, and this leads to numerous technical vulnerabilities, which bring privacy concerns and security to the forefront [44]. Implementing an information security system or an intrusion detection system is not auxiliary, it is mandatory. Establishment of a robust security underwater network architecture demands two prerequisites, i.e., determination of security requirements and comprehension of adversaries' strategy to exploit a vulnerability. Accordingly, the adoption of a real-time monitoring concept extends the effectiveness of cyber-defenses and supports early alerts. Threat modeling and risk assessment are key solutions to counter these challenges. They can offer both prediction and rapid evaluation of system vulnerabilities. [PERSON] et al. [86], with the aim to provide solutions to above issues, built an ontology-based model, which integrates well-known datasets (CVE, ATT&CK, etc.) in OWL and RDF formats. In consequence, relations between attack techniques, attack patterns, weaknesses and vulnerabilities are described, to decrease security vulnerabilities. An interesting work about a dynamic risk assessment in autonomous ships is presented in [87]. Interconnection of vast number of sensors, as well as overwhelming computations, increase complexity, which have consequently expanded the attack surface. With the aim to provide cyberattack scenarios, related to the navigation and propulsion systems, based on identified vulnerabilities, two methods are incorporated, i.e., Formal Safety Assessment (FSA), for ranking hazardous scenarios and Cyber Preliminary Hazard Analysis (CPHA), to conduct threat assessment for autonomous vessels. Wormhole [18; 55], a routing attack, in which malicious or compromised node eavesdrops data packets from nearby friendly assets and redistributes them to the attacker's host, can be devastating. [PERSON] et al. [88], present an approach to detect and mitigate wormhole attacks in a UWSN. More specifically, they propose a cooperative detection strategy, in which each node discovers its neighbors through a secure discovery protocol. Their approach is divided into three distinct phases i.e., discovery, silent monitoring, and detection. During the second phase, receiver nodes extract a hash-based signature and reply with report packets containing its ID and the time stamp of the signature, confirming their identity. After executing simulation experiments in OMNET++ ([[https://omnetpp.org/](https://omnetpp.org/)]([https://omnetpp.org/](https://omnetpp.org/)), accessed on 20 November 2022), they validated their model. Traditional routing schemes differ from these in IoUT. Propagation of acoustic signals in water does not allow the integration of terrestrial routing protocols. However, depth can facilitate this challenge. More specifically, in [89], a depth-based secure routing (DBSR) protocol is proposed, based on the most widely used routing protocol in underwater sensor networks, i.e., depth-base routing protocol (DBR), which requires solely the depth information of assets to operate [90]. DBSR broadens its capabilities by implementing distinct steps to enhance security. In particular, before initial communication, each node possesses its own key along with a public key, to use them for verification. Although the general concept of a pair of keys is widely incorporated by IT systems, energy limitations in underwater world can be crucial. Therefore, elliptic-curve cryptography (ECC)-based algorithms were utilized, to decrease the overall overhead of nodes. Finally, a very common method for attack mitigation, is the deployment of honeypots.