## 4 Main Security and Privacy Challenges
### Fog Paradigm Challenges  
The Cloud paradigm has countermeasures for its security and privacy threats. Nevertheless, these countermeasures may not apply to the Fog paradigm due to the active presence at the network Edge of Fog entities. The immediate vicinity where Fog entities operate will confront various threats which may not constitute a good functioning Cloud. The security solutions in the Fog paradigm are improving and increasing as well. However, most of the published literature on Fog computing security and privacy does not provide insights with an extensive assessment of the various issues. Importantly, we elaborate on some security and privacy challenges encountered in the Fog paradigm.  
* Trust Issue: Fog systems face trust design challenges due to the reciprocal demand for trust and the distributed nature of their network. Cloud computing platforms are different since they already consist of pre-designed security models that match the industrial security requirements, granting customers and enterprises some trust measures within the Cloud system. However, this is not so with Fog computing networks which are more exposed and liable to security and privacy attacks. Even though the same security mechanism can be deployed to every Fog node that makes up the Fog computing network, the distributed design also makes it quite challenging to resolve the trust problem [24].
* Malware Attacks: Infecting the Fog computing system with a malware attack is a very high-level challenge in the network. It is carried out to steal sensitive data, breach confidential information, and even refuse service with the help of a virus, spyware, Trojan horse, or Ransomware. To assist Fog computing applications in mitigating these malicious attacks, authentic defense mechanisms for virus or worm detection and advanced anti-malware must be introduced [114].
* Computation--Data Processing: Fog nodes often receive data collected from end-user equipment, processed, sent to the Cloud system, or end-user pieces of equipment are forwarded information transmitted from the Cloud. After the various processes, the data sent from end-users to Cloud systems and the data sent from Fog nodes to the Cloud are different in size and nature. Another challenge here is that several providers have these Fog nodes, making them hard to be trusted due to the many security and privacy shortcomings arising after the processing of data [115].
* Node Attack: Here, the attacker engages physically by targeting to capture the vulnerable nodes. There are moments when the attacker can decide to alter the whole node, cause defects to the hardware, or steal sensitive information from the Fog nodes by digitally sending messages and causing sensor nodes distortion of classified data. Such attacks can have damaging effects on the nodes of the Fog network, and observing these node sensors will help identify issues and deploy some node capturing defense of algorithmic cryptography [114].
* Privacy Preservation: There is a huge concern as customers using CSP, IoT, and wireless systems face data leaks of personal information. It is not easy to preserve this privacy in the Fog network due to the closeness of Fog nodes to the customers' environment, and it can also facilitate gathering plenty of vital information such as identity, location, and utility usages. Privacy leakage can also occur when communication between Fog nodes becomes more frequent [94].