Paper 2023/1089

Security-Performance Tradeoff in DAG-based Proof-of-Work Blockchain Protocols

Shichen Wu, Shandong University
Puwen Wei, Shandong University
Ren Zhang, Cryptape Co. Ltd. and Nervos
Bowen Jiang, Shandong University

Proof-of-work (PoW) blockchain protocols based on directed acyclic graphs (DAGs) have demonstrated superior transaction confirmation performance compared to their chain-based predecessors. However, it is uncertain whether their security deteriorates in high-throughput settings similar to their predecessors, because their acceptance of simultaneous blocks and complex block dependencies presents challenges for rigorous security analysis. We address these challenges by analyzing DAG-based protocols via a congestible blockchain model (CBM), a general model that allows case-by-case upper bounds on the block propagation delay, rather than a uniform upper bound as in most previous analyses. CBM allows us to capture two key phenomena of high-throughput settings: (1) simultaneous blocks increase each other's propagation delay, and (2) a block can be processed only after receiving all the blocks it refers to. We further devise a reasonable adversarial block propagation strategy in CBM, called the late-predecessor attack, which exploits block dependencies to delay the processing of honest blocks. We then evaluate the security and performance of Prism and OHIE, two DAG-based protocols that aim to break the security-performance tradeoff, in the presence of an attacker capable of launching the late predecessor attack. Our results show that these protocols suffer from reduced security and extended latency in high-throughput settings similar to their chain-based predecessors.

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blockchainProof of WorksDAGconsensus protocol
Contact author(s)
shichenw @ mail sdu edu cn
pwei @ sdu edu cn
ren @ nervos org
bowen jiang @ mail sdu edu cn
2023-07-16: approved
2023-07-13: received
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      author = {Shichen Wu and Puwen Wei and Ren Zhang and Bowen Jiang},
      title = {Security-Performance Tradeoff in DAG-based Proof-of-Work Blockchain Protocols},
      howpublished = {Cryptology ePrint Archive, Paper 2023/1089},
      year = {2023},
      note = {\url{}},
      url = {}
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