## 3 Security and Privacy of Computing Paradigms
### Fog-Related Aspects  
Many businesses have transformed massively, especially with the fast growth in large data usage, due to Cloud computing [80]. Meanwhile, the quest for private services also began to grow hugely. A great number of well-centralized systems is offered by Cloud computing platforms [81; 82], although with some shortcomings. Clouds and their endpoints show certain unwanted long and irregular delays and time-conscious services to some [83]. There is a pertinent high risk in a situation whereby there is a breakdown in the information building and between network interconnected systems. One potential breach here is possible privacy exposure. To mitigate this challenge, the Fog computing [84] model was introduced, and it assisted Cloud-Edge in improving computation, security, and privacy, which is now the leading and most recommended computing service.  
Fog devices are considered to be separate and distributed pieces of equipment ranging from gateways, routers, switches, or professional installation of traditional servers [85]. Furthermore, with the current demand for huge emission reduction, Fog computing is highly viewed as a smart green platform with sustainability and great security benefits. Many fog Nodes (FNs) are seen as renewable constitute the Fog computing system. The geographical placing of FNs can be spread throughout several locations. A great level of pressure exerted in the information center during computation is vastly decreased due to the different FNs working independently but together through a well-calculated formula. Fog can separate or sifter the processing at the central layer found at the middle of the endpoint and Cloud [86], which may significantly enhance the QoS and brings down expenses [87]. Fog computing was highly considered in great demand to deal with the ever-growing IoT issues, as we shall see in the next sub-Section [88].  
Fog computing was established as the most viable approach because of its ability to cross-connect every digital equipment, wireless endpoint, and local device. This interconnectivity is vulnerable to vital security and privacy violations such as disclosing clients' data location, leaking classified documents, and stealing private accounts. First considered by Cisco, Fog computing was brought to expand the Cloud activities to the system's Edge. The consideration of Fog computing surfaces as an option to local Cloud offering huge assistance in terms of QoS, latency, and location distribution [45]. Services such as networking, storage, and most importantly, computing between the customer and information center are rendered by Fog computing hugely considered a virtualized system [89], carrying the related vulnerabilities along the way.  
According to the Edge system, every single unit in the Edge computing functions independently to see that information is not forwarded to the Cloud, and instead, it is locally handled. On the other hand, transferring to Cloud or processing the data from various information origins is always a decision made by Fog computing nodes, taking into account its assets. Fog computing can expand some Cloud services that are not assisted in Edge structure, such as Infrastructure as a service (IaaS), software as a service (SaaS), and platform as a service (PaaS). Fog computing is completely Edge inclined but can be supported by Fog computing while at the Edge of the network, expansion of communication assets and computation are performed [90].