S. no. Reference Year Technology used Summary of the work Shortcoming of the work Possible solution Implementation remarks 6. [78 ] 2020 (a) Smart contract, (b) Ethereum blockchain, (c) federated ML, (d) IPFS Framework combines smart contracts (Ethereum blockchain), differential privacy, and federated ML to enforce trustworthiness and privacy on IIoT data. The work is simulated using Python and socket programming. There is significant latency Investigate different approaches to reduce latency which further improves the efficiency of the system Ganache is used as a test network for the local experiments 7. [79 ] 2020 (a) IoT, (b) blockchain, (c) cloud server Blockchain and cloud assisted secure authentication protocol for the IoT-enabled telecare medical information system Service providers store the data on cloud servers. Therefore, SPOF may exist in the system IPFS mechanism can be used as distributed storage Protocol simulation shows that the computational cost is , and communication cost is 8. [80 ] 2020 (a) IoT, (b) blockchain, (c) cloud server, (d) edge computing server A blockchain-enabled framework to minimize the energy consumption of IoT devices integrating the edge and cloud computing servers Blockchain only used to store the IoT data Only few parameters are simulated, and blockchain execution in the real networks is one of possible solutions to increase the throughput of the system Average response time and energy consumption of the solution are lower than those in the existing schemes 9. [81 ] 2021 (a) IoT, (b) blockchain Private blockchain-enabled cipher-policy attribute-based encryption scheme for IIoT Deep analysis of smart contract mechanism required State machine model-based smart contracts can be designed Smart contract languages such as Solidity can be used for writing the contracts among the IIoT entities 10. [82 ] 2021 (a) IoT, (b) blockchain, (c) cloud server, (d) software-defined network A software-defined networking and blockchain-enabled framework for the evidence collection and provenance preservation Smart contract mechanism can be used to automate the whole system State machine model-based smart contracts can be designed Simulation result reveals that the performance of the system is better while increasing the number of users and load on the system