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DracoBFT Overview

DracoBFT is a leader-based, view-driven BFT consensus protocol implementing Fast-HotStuff two-chain finality rule. It achieves sub-second finality with linear view-change complexity and O(m) state commitment costs. Pipelined Operation

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System Model

The protocol operates under the partially synchronous network model:
  • n = 3f + 1 validators, tolerating up to f Byzantine faults.
  • Partial Synchrony: After GST, message delivery bounded by a known constant.
  • Authenticated Channels: All messages signed with digital signatures.
  • Collision-Resistant Hashing: SHA256 for state commitments.

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Two-Chain Finality

A block B at view v is finalized when a child block B’ at view v+1 contains a QC for B. Two-Round Commit Protocol Finality time: 2 rounds (versus 3 rounds for standard HotStuff).

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Vote Rule

Validators only vote for blocks that directly extend a certified block: 
proposal.block.view == proposal.block.qc.view + 1
This enforces consecutive views, ensuring the Fast-HotStuff safety property.