## 2 Background  
Identity and access management (IAM) is a critical component for maintaining security within industrial environments, which include factories, power plants, and other critical infrastructure. These settings require stringent security measures to safeguard both physical and digital assets. IAM systems are crucial for controlling who has access to various parts of an industrial facility and ensuring that only authorized personnel can perform specific tasks. IAM involves processes, policies, and technologies that ensure the right individuals have access to the right resources at the right times for the right reasons. Traditional IAM methods often rely on static rules and manual oversight, which can be inadequate against evolving security threats and the increasing complexity of industrial operations. One of the main challenges in industrial environments is managing access to a wide range of resources, including physical assets, digital systems, and data. This requires a comprehensive IAM system capable of handling the complexity and scale of industrial operations while ensuring security and regulatory compliance. IAM systems in industrial environments must accommodate both IT and OT (operational technology) integration, which requires managing access across traditional IT infrastructure and specialized OT systems. This environment necessitates real-time access control and anomaly detection due to the potential impact on production and safety, which differs from general IAM systems typically focused on standard IT environments. Furthermore, industrial IAM must be scalable and flexible to manage a wide range of devices, from sensors to complex machinery, which contrasts with general IAM solutions that primarily focus on user-based access rather than extensive device-level interoperability. IAM systems in industrial environments must address several key requirements, including the following:* User Management and Authentication: In industrial IAM systems, centralized and distributed user management authentication models offer distinct advantages and limitations. Centralized models simplify user management and control through a single authentication server, which efficiently oversees access, enables single sign-on (SSO), and streamlines policy enforcement across systems. However, they are prone to single points of failure and potential security vulnerabilities due to centralized data handling [11]. Distributed authentication, increasingly enabled by blockchain, mitigates these risks by distributing trust and authentication tasks across a network, reducing the chance of total system failure while enhancing data privacy and scalability. Blockchain-based models, like RC-AAM, avoid central dependency and enable decentralized role-centric authentication, enhancing security in industrial and IoT settings [12]. While distributed models offer robustness and fault tolerance, they often demand higher technical complexity and infrastructure to implement effectively, highlighting a trade-off between centralized simplicity and distributed resilience. * Access Control: Industrial IAM systems employ various access control models tailored to the complexity and security requirements of industrial environments. Role-based access control (RBAC), adapted with node-based and hierarchical features, remains foundational due to its simplicity in managing roles across different users [13]. Attribute-based access control (ABAC) adds flexibility by using device and user attributes, making it effective for systems like programmable logic controllers (PLCs) [14]. Multi-granularity models are also applied in Industry 4.0 settings to adjust access across product life cycles, improving management efficiency [15]. Additionally, task-role-based access control (T-RBAC) aligns permissions with specific tasks, adding another layer of role differentiation [16], and context-aware access control adapts permissions dynamically based on environmental factors, enhancing security in real-time industrial operations [17].