## 3 Overview of IoT System Security Applications in the Industrial Field
Blockchain is a new generation of safe data technology that is revolutionizing business and industry [78]. In this regard, [PERSON] et al. in [79] presented an innovative and secure architecture for the security of e-healthcare data using a distributed ledger technology based on a blockchain known as BIoMT. Additionally, they created a distributed tiered hierarchy for medical wireless sensor networks (WSNs) to manage and optimize data. This structure improves the network resources, and fosters trust in the peer-to-peer (P2P) environment enabled by blockchain technology. Lastly, the BHIIIoT (blockchain for industrial Internet of Things) safeguards shared resources in blocks kept in an unchangeable blockchain archive by using the NuCypher threshold re-encryption process. Industry 4.0 introduces additional security risks beyond conventional industrial networks due to the integration of operating technology (OT) and IT infrastructures. Defense-in-depth (DiD) tactics provide many levels of protection, each focusing on a distinct set of menaces to address the complexity of this issue. Given that data pass through intermediate entities, or middleboxes, before achieving their purpose, [PERSON] et al. in [80] propose a combination of DiD, a lightweight end-to-end (EEE) encryption algorithm called attribute-based encryption (ABE), and object security (e.g., OSCORE) to achieve a comprehensive E2E security method. If middleboxes are compromised, vulnerable information could be exposed to prospective hackers if not encrypted along this path. Figure 13 shows how the three security zones are divided. The absence of a threat database is one of the many obstacles that still need to be overcome to use a universal approach for threat modeling in smart manufacturing systems. Consequently, to close this gap and save time and effort, [PERSON] et al. created a rule-based threat database and component catalog to handle potential security concerns in smart manufacturing systems [81]. They perform STRIDE (a spoofing, tampering, repudiation, and information disclosure model that focuses on identifying potential risks in each system component) based threat modeling against a smart factory use case using Microsoft Threat Modeling Tool. First, their data flow model of the development process refers to the ENISA high-level model based on the Purdue model; Figure 14 illustrates the levels that make up the model. The model comprises production machines, sensing devices, control devices (HMI and PLC panels), data processing and visualization software, and cloud servers. [PERSON] et al. improved what was previously called flexible manufacturing system (FMS) by defining a new paradigm, the IoT-enabled system, overcoming the previous limitations of the FMS, such as high initial costs, obsolete technology, integration complex in the system, and long setup times [82]. IoT-enabled systems allow the analysis of valuable data continuously gathered from several sources across the industrial ecosystem. This approach improves decision making, PdM, process optimization, and energy efficiency. In fact, by facilitating secure communication in an IoT-enabled system representing the smart manufacturing sector, these solutions provide a unique method of mutual authentication among the FMS unit, users, and server. Session keys are established to accomplish this security. Outperforming prior schemes, the authors in [82] devised a technique that displays strong resilience against numerous security assaults. Its considerable security benefits outweigh the minor increase in communication overhead compared to various baseline methods. First, they suggest a plan that permits key agreement and mutual authentication to strengthen the security of the smart manufacturing sector. The proposal states that the server will provide mutual authentication among users and the FMS unit and between the user and the server. During this process, session keys are formed via the FMS unit, the server, and the user.