FortunChain: EC-VRF-Based Scalable Blockchain System for Realizing State Sharding

The low throughput of traditional blockchain can hardly support the demand of high-frequency and high-concurrent application scenarios, which severely restricts the practical application of blockchain and becomes a bottleneck for blockchain development. Sharding is a potential solution to this issue. Existing sharding schemes mostly use complicated PBFT or its variants consensus protocols, with diminishing consensus performance as the number of nodes grows, and global consistency of transaction data is a challenge due to parallel block generation. Aiming at the above problems, we propose an efficient and scalable sharding blockchain system named FortunChain that comprises a verification chain and multiple sharding chains. In the FortunChain, a novel Tyche consensus protocol is designed to select the set of sharding verification nodes and accounting nodes probabilistically leveraging the newly constructed elliptic curve-based verifiable random function (EC-VRF), which ensures the efficiency, unpredictability and security of node selection. Multi-period, fast and dynamic sharding accounting is implemented in the sharding chain to improve the performance of transaction processing. After that, the verification chain is responsible for the secondary verification by applying the batch verification algorithm to the blocks submitted by the shards and then generating the verification block. Each shard stores the sharding state by synchronizing the verification chain to realize the state sharding and ensure the global consistency of the transaction data. Simulation results show that the throughput of FortunChain can reach approximately 6540tx/s and the estimated latency is 8.59s, which demonstrates its efficiency and feasibility.