Towards Next-Generation Proof-of-Authority (PoA) Consensus

  1. absolute finality (or safety guarantee) on blocks and transactions;
  2. significant reduction of the platform’s risk of being temporarily disrupted = better stability of blockchain service;
  3. faster-converging probabilistic finality = faster transaction confirmation for applications.


We propose to introduce two new mechanisms into the existing PoA protocol.

Committee-Endorsing Mechanism

The committee-endorsing mechanism fundamentally changes the way a block is created. More specifically, besides the selected block producer, it demands other nodes to participate in the process of forming a new block.

  1. he colludes with a number of other nodes; and
  2. among those nodes there are, by chance, a sufficient number of them being selected as a committee member.

Block Finality Mechanism

The block finality mechanism grants qualified blocks absolute safety guarantee. Once a block acquires its finality, the consensus will assure that it cannot be modified, replaced or removed from the public ledger even when the network encounters some extremely asynchronous situation such as being subject to large-scale network partitioning.


The next-generation PoA will introduce

  • committee-endorsing mechanism that significantly lowers the possibility of a node manipulating his right to produce a new block and results in faster converging probabilistic finality;
  • block-finality mechanism that grants absolute safety guarantee to blocks (as well as the included transactions) that qualify certain criteria.

Implementation Roadmap

The implementation, testing and integration of the new POA consensus on VeChainThor will have to go through multiple phases. We would expect a brand new test net to be launched for the debugging and testing purposes. Moreover, details of the algorithm will be published in multiple VeChain Improvement Proposals (VIPs). I will write about these VIPs in my future articles.


[1] Yin, M., Malkhi, D., Reiter, M.K., Gueta, G.G., Abraham, I.: Hotstuff: BFT consensus in the lens of blockchain. arXivpreprint arXiv:1803.05069 (2018)



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