An optimized transaction verification method for trustworthy blockchain-enabled IIoT

The blockchain technology is one of the hottest research fields in recent years, and it can provide a new security solution for data transmission and storage under trust-free environments. The distributed structure of blockchain is naturally suitable for the Industrial Internet of Things (IIoT), which can be used to build distributed trustworthy IIoT with high security. The transaction database is the most important security component in the blockchain-enabled IIoT systems. Each valid transaction must be recorded in the database on the long connected blockchain. Merkle tree is designed for the transaction verification and it can guarantee the data integrity and security. Therefore, the Merkle tree has the same and fixed verification time for every transaction. Due to the human elements, only a few transactions will be verified frequently in some real scenarios. The current Merkle tree storage structure can not improve the verification efficiency for transactions that require frequent verification in IIoT systems with heterogeneous Devices. To tackle the issue, this paper proposes an optimized Merkle tree structure for efficient transaction verification in trustworthy blockchain-enabled IIoT systems. This work first analyzes the current building method and verification mechanism of the Merkle tree structure. Then we propose the optimized Merkle tree structure and its construction and verification. Finally, the superiority of our proposed method is proved through extensive experiments. The new Merkle tree structure is more efficient for verifying blockchain transactions for trustworthy blockchain-enabled IIoT systems.