Sharding: A Secure and Scalable Solution for Next-Generation Blockchain

Starting from Bitcoin transactions, blockchain technology emerged as a ground-breaking innovation and has spread its wings in various applications like the Internet of Things, supply chains, finance and healthcare. However, the scalability limitations of the blockchain have been a significant barrier to its extensive-scale adoption and performance. To address this challenge, one evolving approach is Sharding, which simultaneously balances decentralization, security, and scalability. Sharding is a technique that splits the network into distinct units, popularly termed as shards. Each shard operates independently and is responsible for processing its portion of the network’s state and transaction workload. It allows multiple transactions to be executed in parallel, significantly boosting speed, efficiency, and reducing latency. The technique considerably improves the throughput compared to conventional blockchain, where every node processes transactions. This article critically analyses the sharding types, protocols, their strategies, variety of consensus used, and the building blocks of sharding. Further, it explores shard-based blockchain platforms and presents the recent work on sharding for different domains. This review describes the potential security attacks and their countermeasures. The study presents a small experimental case study by implementing a lightweight adaptive sharding strategy to demonstrate how sharding behaves in practise under realistic IoT transaction loads so that the readers could bridge the gap between the theoretical and practical framework under controlled simulated environment. Further, it highlights the research gaps that lays the foundation for future research and development, enabling the researchers to focus and understand the sharding solutions in the Blockchain ecosystem.