[Hackathon] PBFT coordination: BFT consensus, view-change, adversaria…#45
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lily1c wants to merge 2 commits into
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[Hackathon] PBFT coordination: BFT consensus, view-change, adversaria…#45lily1c wants to merge 2 commits into
lily1c wants to merge 2 commits into
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Problem 10 — Partition-tolerant BFT coordination (PBFT)
Implements Castro-Liskov PBFT as a coordination plugin (pbft), alongside contract_net.
What's included
Three-phase signed consensus (pre-prepare / prepare / commit) with 2f+1 quorum certificates. Votes are signed via did_key; forged votes are rejected at resolve and commit.
Safe view-change: on leader failure, replicas issue signed view-change messages carrying prepared-proofs, and the new leader is bound to re-propose any prepared value — so no committed value can be dropped across a view change.
Four adversarial validators, each tested in both directions (catches the attack, passes honest traces): conflicting-commits, forged-quorum, equivocation, stuck-view.
Two scenarios: bft_partition (7 replicas, 4/3 split — minority below quorum commits nothing) and bft_byzantine (7 replicas, f=2 equivocating).
Safety argument: any two 2f+1 quorums out of 3f+1 overlap in an honest replica, which signs only one value per slot — so conflicting commits are impossible, and the view-change binding preserves this across leader changes.
Tests: 37 passing (test_pbft.py, test_coordination_validators.py, test_bft_scenarios.py), ruff-clean