QBFT Consensus

QBFT, Quorum Byzantine Fault Tolerance, is a consensus protocol for networks with a known set of validators rather than open mining. Validators take turns proposing blocks. Each proposal passes through a prepare phase and a commit phase, and a block joins the chain only once a quorum of validators has signed it. Quorums are sized to overlap in honest validators, so conflicting blocks can never both collect enough signatures. The result is immediate finality: no forks, no reorganizations, no waiting for confirmations. The protocol keeps working as long as the honest validators can still form a quorum, even if the rest are faulty, offline, or malicious.

Chain 2800 runs QBFT with nine validators and a quorum of six, producing one block roughly every 500 ms. The commit signatures that finalize each block are classical ECDSA on secp256k1, recorded in the block header. Consensus itself is therefore not post-quantum, and Aere does not claim that it is. What the chain adds is a distinct layer on top: since block 13,014,000, every 32nd header carries a seal certificate of Falcon-512 signatures from the validators over the parent block, and a 32-byte digest of that certificate sits inside the data covered by the block hash. That mechanism is the post-quantum anchor.

A second, independently implemented client validates every block alongside the producing client, so a consensus defect in either implementation surfaces as a disagreement between them instead of a silent failure. See client diversity.