The Hermes BFT for Blockchains

Mohammad Mussadiq Jalalzai, Chen Feng, Costas Busch, Golden Richard, Jianyu Niu

Research output: Contribution to journalArticlepeer-review


The performance of partially synchronous BFT-based consensus protocols is highly dependent on the primary node. All participant nodes in the network are blocked until they receive a proposal from the primary node to begin the consensus process. Therefore, an honest but slack node (with limited bandwidth) can adversely affect the performance when selected as primary. Hermes decreases protocol dependency on the primary node and minimizes transmission delay induced by the slack primary while keeping low message complexity and latency with high scalability. Hermes achieves these performance improvements by relaxing strong BFT agreement (safety) guarantees only for a specific type of Byzantine faults (also called equivocated faults). Interestingly, we show that in Hermes equivocating by a Byzantine primary is expensive and ineffective. Therefore, the safety of Hermes is comparable to the general BFT consensus. We deployed and tested Hermes on <formula><tex>$190$</tex></formula> Amazon <formula><tex>$EC2$</tex></formula> instances. In these tests, Hermes's performance was comparable to the state-of-the-art BFT protocol for blockchains (when the network size is large) in the absence of slack nodes. Whereas, in the presence of slack nodes, Hermes outperforms the state-of-the-art BFT protocol significantly in terms of throughput and latency.

Original languageEnglish (US)
JournalIEEE Transactions on Dependable and Secure Computing
StateAccepted/In press - 2021
Externally publishedYes


  • Bandwidth
  • Blockchains
  • Byzantine Fault Tolerance
  • Complexity theory
  • Consensus
  • Consensus protocol
  • Delays
  • Performance
  • Proposals
  • Safety
  • Scalability
  • Scalability
  • Security
  • Throughput

ASJC Scopus subject areas

  • Computer Science(all)
  • Electrical and Electronic Engineering


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