🤖 AI Summary
Existing blockchain sharding systems require large shard sizes to ensure security, limiting the number of shards and thus constraining concurrency and scalability. This paper proposes the Linked Cross-shard Endorsement (LCE) protocol, which introduces the novel concept of “corrupted shards”—shards permitted to contain a higher proportion of Byzantine nodes—while enforcing cross-shard chain-based endorsement to ensure collaborative validation across shards. This enables finer-grained, higher-count sharding without compromising security. Built upon the Harmony framework, LCE integrates dynamic shard reconfiguration, asynchronous cross-shard consensus, block-level chained endorsement, and a multi-layer verification mechanism. Evaluated on a 4,000+ node network, the system achieves 19× higher throughput than Harmony, significantly enhancing scalability while formally guaranteeing strong security under standard Byzantine fault-tolerance assumptions.
📝 Abstract
Blockchain sharding improves the scalability of blockchain systems by partitioning the whole blockchain state, nodes, and transaction workloads into different shards. However, existing blockchain sharding systems generally suffer from a small number of shards, resulting in limited concurrency. The main reason is that existing sharding systems require large shard sizes to ensure security. To enhance the concurrency of blockchain sharding securely, we propose SpiralShard. The intuition is to allow the existence of some shards with a larger fraction of malicious nodes (i.e., corrupted shards), thus reducing shard sizes. SpiralShard can configure more and smaller shards for higher concurrency at the same network size. To ensure security with the existence of corrupted shards, we propose the Linked Cross-shard Endorsement (LCE) protocol. According to our LCE protocol, the blocks of each shard are sequentially verified and endorsed by a group of shards before being finalized. As a result, a corrupted shard can eliminate forks with the help of the other shards. We implement SpiralShard based on Harmony and conduct extensive evaluations. Experimental results show that, compared with Harmony, SpiralShard achieves around 19x throughput gain under a large network size with 4,000+ nodes.