A novel trust mechanism based on Fog Computing in Sensor-Cloud System

In recent years, Sensor-Cloud System (SCS) has become a hot research issue. In this system, there are some cyber security problems that can be well solved by the trust mechanism. However, there are still some deficiencies in existing trust mechanisms, especially for the SCS underlying structure. We proposed a fog-based hierarchical trust mechanism for these cyber security deficiencies. This hierarchical mechanism consists of two parts, trust in the underlying structure and trust between cloud service providers (CSPs) and sensor service providers (SSPs). For trust in the underlying structure, the behavior monitoring part is established and implemented in Wireless Sensor Networks (WSNs), and the fine-grained and complicated data analysis part is moved to the fog layer. For trust between CSPs and SSPs, it focuses more on the real-time comparison of service parameters, the gathering of exception information in WSNs, the targeted quantitative evaluation of entities and so on. The experimental results indicate that this fog-based hierarchical structure performs well in saving network energy, detecting malicious nodes rapidly and recovering misjudgment nodes in an acceptable delay. Furthermore, the reliability of edge nodes is well guaranteed by data analyses in the fog layer and an evaluation strategy based on similar service records is put forward. (C) 2018 Published by Elsevier B.V.