Paper 2024/304

A Two-Layer Blockchain Sharding Protocol Leveraging Safety and Liveness for Enhanced Performance

Yibin Xu, University of Copenhagen
Jingyi Zheng, University of Copenhagen
Boris Düdder, University of Copenhagen
Tijs Slaats, University of Copenhagen
Yongluan Zhou, University of Copenhagen

Sharding is a critical technique that enhances the scalability of blockchain technology. However, existing protocols often assume adversarial nodes in a general term without considering the different types of attacks, which limits transaction throughput at runtime because attacks on liveness could be mitigated. There have been attempts to increase transaction throughput by separately handling the attacks; however, they have security vulnerabilities. This paper introduces Reticulum, a novel sharding protocol that overcomes these limitations and achieves enhanced scalability in a blockchain network without security vulnerabilities. Reticulum employs a two-phase design that dynamically adjusts transaction throughput based on runtime adversarial attacks on either or both liveness and safety. It consists of `control' and `process' shards in two layers corresponding to the two phases. Process shards are subsets of control shards, with each process shard expected to contain at least one honest node with high confidence. Conversely, control shards are expected to have a majority of honest nodes with high confidence. Reticulum leverages unanimous voting in the first phase to involve fewer nodes in accepting/rejecting a block, allowing more parallel process shards. The control shard finalizes the decision made in the first phase and serves as a lifeline to resolve disputes when they surface. Experiments demonstrate that the unique design of Reticulum empowers high transaction throughput and robustness in the face of different types of attacks in the network, making it superior to existing sharding protocols for blockchain networks.

Note: Minor changes for clarity.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Minor revision. Network and Distributed System Security (NDSS) Symposium 2024
blockchain sharding
Contact author(s)
yx @ di ku dk
2024-07-12: last of 2 revisions
2024-02-23: received
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      author = {Yibin Xu and Jingyi Zheng and Boris Düdder and Tijs Slaats and Yongluan Zhou},
      title = {A Two-Layer Blockchain Sharding Protocol Leveraging Safety and Liveness for Enhanced Performance},
      howpublished = {Cryptology ePrint Archive, Paper 2024/304},
      year = {2024},
      doi = {10.14722/ndss.2024.24006},
      note = {\url{}},
      url = {}
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