An SGX-based execution framework for smart contracts upon permissioned blockchain

Since consensus protocol and execution mechanism act as two key factors for the overall throughput of blockchain systems, how to execute smart contracts efficiently becomes an emergent bottleneck as many high-performance consensus protocols have been proposed in recent years. Due to the existence of Byzantine nodes, existing concurrency approaches can only achieve intra-node concurrency, not inter-node concurrency. Fortunately, since the trust among nodes can be achieved based on the confidentiality guarantee provided by the trusted execution environment, such as Intel Software Guard Extensions (SGX), we propose a novel concurrent execution framework using SGX, which is the first to achieve both intra- and inter-node concurrency. Specifically, each replica executes the task assigned by the primary in parallel and gets trusted results using SGX firstly. Then, each node obtains the execution results of others via state replication to achieve consistency. However, we must ensure the integrity and correctness of all data transferred to SGX for getting the trusted results. Therefore, we design a novel approach to efficiently generate Merkle multiproofs and verify data in parallel. Theoretical analysis and experimental results show that the proposed scheme significantly outperforms state-of-art solutions.