VBFT Algorithm | cryptocurrencies, blockchains & live prices

VBFT (Verifiable Byzantine Fault Tolerance) is the consensus protocol used by the Ontology blockchain, combining elements of verifiable random functions (VRF), Byzantine Fault Tolerance, and delegated proof-of-stake. The protocol selects a group of consensus candidates through a VRF-based lottery, where validators' chances of selection are weighted by their staked ONT tokens. From this candidate pool, three roles are randomly assigned: block proposers who generate candidate blocks, block verifiers who validate proposals, and block confirmers who provide the final confirmation vote. The VRF ensures that the selection process is random and verifiable — anyone can check that a validator was legitimately selected, but no one can predict the selection in advance.

VBFT provides fast finality (approximately 5-7 seconds per block) with Byzantine fault tolerance guarantees. The multi-role design — with separate proposer, verifier, and confirmer groups — adds layers of security since an attacker would need to control participants across multiple randomly selected groups simultaneously. The VRF-based selection provides protection against targeted attacks since upcoming consensus participants are unknown until they self-identify. VBFT is designed to support a large validator pool while maintaining efficiency, as only a subset of validators participates in each consensus round. The protocol can tolerate up to one-third of validators being Byzantine within each consensus group.

VBFT has been running on the Ontology mainnet since its launch in June 2018. Ontology is a high-performance blockchain platform focused on digital identity and data solutions, founded by Li Jun and developed by Onchain (a blockchain technology company based in China). The network supports both a native Ontology Virtual Machine and a NeoVM for smart contract execution, and has emphasized enterprise adoption and identity-related use cases. Ontology's consensus design reflects its goal of providing a blockchain suitable for business applications where both performance and security are required, and the VRF-based validator selection adds a layer of unpredictability that enhances the protocol's resistance to targeted attacks.