PolyShard: Coded Sharding Achieves Linearly Scaling Efficiency and Security Simultaneously

Songze Li, Mingchao Yu, Chien Sheng Yang, Amir Salman Avestimehr, Sreeram Kannan, Pramod Viswanath

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Today's blockchain designs suffer from a trilemma claiming that no blockchain system can simultaneously achieve decentralization, security, and performance scalability. For current blockchain systems, as more nodes join the network, the efficiency of the system (computation, communication, and storage) stays constant at best. A leading idea for enabling blockchains to scale efficiency is the notion of sharding: different subsets of nodes handle different portions of the blockchain, thereby reducing the load for each individual node. However, existing sharding proposals achieve efficiency scaling by compromising on trust - corrupting the nodes in a given shard will lead to the permanent loss of the corresponding portion of data. In this paper, we settle the trilemma by demonstrating a new protocol for coded storage and computation in blockchains. In particular, we propose PolyShard: 'polynomially coded sharding' scheme that achieves information-theoretic upper bounds on the efficiency of the storage, system throughput, as well as on trust, thus enabling a truly scalable system. We provide simulation results that numerically demonstrate the performance improvement over state of the arts, and the scalability of the PolyShard system. Finally, we discuss potential enhancements, and highlight practical considerations in building such a system.

Original languageEnglish (US)
Article number9141331
Pages (from-to)249-261
Number of pages13
JournalIEEE Transactions on Information Forensics and Security
StatePublished - 2021
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Safety, Risk, Reliability and Quality
  • Computer Networks and Communications


  • Scalability
  • blockchain
  • coded sharding
  • decentralized networks
  • information theory
  • security and trust


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