Security Analysis of Sharding in the Blockchain System

The design of sharding aims to solve the scalability challenge in a blockchain network. Typically, by splitting the whole blockchain network into smaller shards, the transaction throughput can be significantly improved. However, distributing fewer attesting nodes for transactions in a shard may cause higher security risks. This paper analyzes the security level of transaction verification in different types of shards and transactions. The analyzed result indicates that the size of shards and validating nodes number may influence the transaction security in shards. And the random distribution of attesting nodes can reduce such influence and improve the reliability of consensus in shards.