# Performance Analysis of a Keyword-Based Trust Management System for Fog Computing
## 1 Introduction
The kinds of security features offered by the fog are predicated on the needs of life-safety-critical systems. As a result, the expansion of the fog presents significant difficulties in terms of security and trust. Because of its mobility, heterogeneity, and large-scale geo-distribution, the established approaches cannot be directly applied to the fog [24]. We provide a thorough fog architecture based on the current computer architecture with three levels [11]: the cloud, the fog, and the edge. A core network providing network services sits between the cloud and the fog. The diagram clearly shows that the cloud is located at the center of the network, far from any devices in the periphery. Fog infrastructure is situated between the cloud and edge devices. The fog nodes are all linked to the cloud, and fog nodes [8] are connected to each edge device. Further, links may be established between fog nodes. All conversations occurring between Fog-Fog, Fog-Cloud, and Fog-Edge are two-way. Broadcasting, data warehousing, and extensive data analysis may all use the cloud's high-performance servers and storage devices [25]. The cloud is the nerve center for remote control and administration, storing massive amounts of data and performing sophisticated but usually non-urgent operations. Information is sent to the cloud over a fast network, either wirelessly or via wires. If you need complete worldwide protection, the cloud has you covered. It is a central location for storing and organizing information for future use, and it may also perform insightful analyses. The fog comprises a set of nodes that are all related to one another [25]. It offers geo-distributed, low latency, urgent computation, and location awareness. Every fog network node serves as a temporary data storage hub. Among its many uses, it facilitates network transformation, data gathering, communication, upload, storage, calculation, and administration. Fog nodes can handle massive amounts of data from edge devices because they have more memory or storage capacity for processing. The computation work should be sent to the cloud by fog nodes using various communications technologies, such as 3G, 4G, and 5G cellular networks, and Wi-Fi when more complex and lengthy computation is required. Fog nodes connect the cloud to devices at the network's periphery. In the fog, each node operates alone, but may link with others to work together. Management and collaborative processes are implemented on fog nodes to establish command and control. Remote or local communications may be used to cooperate among fog nodes. The periphery consists in all the cars, machines, and mobile phones that can be identified, sense their surroundings, and communicate with one another [25]. One of the fog nodes is linked to every edge device, and sensors and local data are abundant in edge devices. Sending all the data from terminal edge devices to the cloud over a network is time-consuming and costly. As a result, connecting edge devices to fog nodes allows for handling urgent data without its direct transmission to the cloud. Contextual and data-dependent security threats are two examples of newer threats that have recently emerged. Trust is widely recognized as a critical topic. Therefore, this effort aims to compile an overview covering the security and trust concerns in fog computing and similar architectures. Relationships between fog nodes and edge devices are greatly aided by trust, built on the backs of prior interactions between the two sets of nodes and devices. Due to its vital role in protecting users' anonymity and privacy, a fog node is often regarded as the system's most essential piece of hardware [25]. In addition, delegation relies on the credibility of this part, since users will want reassurance that the fog node will globally mask their provided data and will only be used for peaceful purposes. This demands a degree of confidence between all of the fog network's nodes.