Blockchain based consensus checking in decentralized cloud storage

As a popular application of cloud computing, cloud storage has been widely used. In distributed computing system, blockchain as a secure mechanism is often used to store data, such as account information, trading record, and others. Once any data is saved in blockchain, it is sealed and cannot be changed any more. All the data copies must be consistent in blockchain. In cloud computing, data is always duplicated to prevent the data loss. However, the consensus issue of different data copies may appear in various data operations. Sometimes the results of data operations may be seriously affected. As a useful technique, blockchain can effectively maintain the data consistency in a distributed computing system, including the cloud-based applications, such as cloud storage. Based on a specific type of blockchain called practical Byzantine fault tolerance (PBFT), this paper proposes a synchronous Byzantine fault tolerance (SBFT) algorithm that not only maintains the data consistency, but also has much higher efficiency than other general blockchain algorithms. In a small cloud environment, SBFT is simulated to compare with both Byzantine fault tolerance (BFT) and PBFT. The experiment results demonstrate the better performance of SBFT in data consistency, efficiency, and reliability.