Blockchain sharding is a promising approach to solving the dilemma between decentralisation and high performance (transaction throughput) for blockchain. The main challenge of Blockchain sharding systems is how to reach a decision on a statement among a sub-group (shard) of people while ensuring the whole population recognises this statement. Namely, the challenge is to prevent an adversary who does not have the majority of nodes globally but have the majority of nodes inside a shard. Most Blockchain sharding approaches can only reach a correct consensus inside a shard with at most $n/3$ evil nodes in a $n$ node system. There is a blockchain sharding approach which can prevent an incorrect decision to be reached when the adversary does not have $n/2$ nodes globally. However, the system can be stopped from reaching consensus (become deadlocked) if the adversary controls a smaller number of nodes. In this paper, we present an improved Blockchain sharding approach that can withstand $n/2$ adversarial nodes and recover from deadlocks. The recovery is made by dynamically adjusting the number of shards and the shard size. A performance analysis suggests our approach has a high performance (transaction throughput) while requiring little bandwidth for synchronisation.

中文翻译：

---

一个灵活的 n/2 对手节点抵抗和停止可恢复的区块链分片协议

区块链分片是解决区块链去中心化和高性能（交易吞吐量）之间困境的一种很有前途的方法。区块链分片系统的主要挑战是如何就一个子群体（分片）之间的陈述做出决定，同时确保整个人群都认可这一陈述。也就是说，挑战是防止对手在全球范围内没有大多数节点但在分片内拥有大多数节点。大多数区块链分片方法只能在 $n$ 节点系统中最多具有 $n/3$ 个邪恶节点的分片内达成正确的共识。有一种区块链分片方法可以防止对手在全局范围内没有 $n/2$ 节点时做出错误的决定。然而，如果对手控制的节点数量较少，则可以阻止系统达成共识（陷入僵局）。在本文中，我们提出了一种改进的区块链分片方法，可以承受 $n/2$ 的对抗性节点并从死锁中恢复。恢复是通过动态调整分片数量和分片大小来实现的。性能分析表明我们的方法具有高性能（事务吞吐量），同时需要很少的同步带宽。