Security-Aware GA Based Practical Byzantine Fault Tolerance for Permissioned Blockchain

Achieving good performance in terms of throughput and scalability, with high quality of security has always been a challenging problem in all sorts of scheduling. Permissioned blockchain allows multiple contracts of non-trusting peer organization to be deployed for working in consortium. It is the responsibility of the scheduler often called as an ordering service to form block of transactions to get committed through consensus. Practical Byzantine Fault Tolerance (PBFT) is one of the most popular consensus algorithm used in current implementations of blockchain. Most consensus algorithms including PBFT follow FIFO scheduling strategy to create the block of transactions. With block chain being supported for multi-contract environment, scheduling should consider difference in service requirements specifically security requirement for heterogeneous contracts. The current work proposes SAGA-PBFT (Security-Aware Genetic Algorithm based Practical Byzantine fault Tolerance) scheduler, which uses multi objective genetic algorithm for balancing the security requirement and security overhead at the time of block creations. The algorithm assigns the security level to each transaction as per its security requirement but in an unpredictable manner making security attack difficult. It further uses security aware PBFT for consensus. Experimental simulation proves that SAGA-PBFT when compared with PBFT, achieves better commit time and scalability with best possible security.