Consensus

QuantumCoin uses a deposit-weighted BFT consensus protocol (proof of stake) with four message phases (Proposal, Acknowledgment, Precommit, Commit) that provides immediate deterministic finality for every block. Safety holds regardless of network timing; liveness is guaranteed under the standard partial synchrony model.

Each block permits at most two rounds: Round 1 attempts normal consensus, and Round 2 forces a NIL (empty) block to guarantee progress. This two-round design avoids the unbounded retry loops that the FLP impossibility result precludes in purely asynchronous settings. A per-block committee of up to 128 validators is selected from an unbounded registered set, with all quorum thresholds weighted by deposit, tolerating Byzantine faults comprising strictly less than one-third of the committee's effective deposit.

Read more in Consensus Whitepaper (PDF).