The Internet of Things (IoT) architecture is commonly organized into multiple layers to simplify the design, deployment, and management of interconnected devices and services. These layers define how data is sensed, transmitted, processed, and utilized while ensuring security, reliability, and scalability. Although different models exist, a widely accepted representation includes the perception layer, network layer, middleware or processing layer, application layer, and business layer. From a security perspective, each layer introduces unique vulnerabilities and protection requirements, making layered architecture essential for implementing defense-in-depth strategies in IoT environments. The perception layer, also known as the sensing or device layer, forms the foundation of IoT architecture. It consists of physical devices such as sensors, actuators, RFID tags, cameras, and embedded systems that collect environmental data like temperature, motion, humidity, or location. These devices interact directly with the physical world and convert real-world signals into digital information. Because devices at this layer are often resource-constrained, deployed in remote locations, and sometimes physically accessible to attackers, they face significant security risks such as device tampering, hardware manipulation, side-channel attacks, and unauthorized firmware modifications. Security mechanisms at this layer include secure boot processes, hardware-based trust anchors, lightweight encryption algorithms, device authentication, and tamper-resistant hardware designs. Ensuring device identity and integrity is critical because compromised devices can act as entry points for large-scale cyberattacks, including botnets and distributed denial-of-service (DDoS) attacks. The network layer is responsible for transmitting data collected by devices to other components in the IoT ecosystem, such as gateways, cloud platforms, or data processing systems. This layer includes communication technologies like Wi-Fi, Bluetooth, Zigbee, cellular networks, LoRaWAN, and Ethernet, along with routing protocols and gateways that connect heterogeneous devices. Since IoT environments rely heavily on wireless communication, they are exposed to threats such as eavesdropping, man-in-the-middle attacks, packet sniffing, replay attacks, and denial-of-service attacks. Security at the network layer focuses on ensuring confidentiality, integrity, and availability of transmitted data through encryption protocols (such as TLS and DTLS), secure routing mechanisms, network authentication, intrusion detection systems, and traffic monitoring. Secure gateways also play an essential role by acting as intermediaries that filter malicious traffic and enforce access control policies before data reaches higher layers. The middleware or processing layer, sometimes referred to as the support