- The VeChainThor blockchain will receive a new consensus algorithm called SURFACE or Proof of Authority 2.0 (PoA 2.0) to meet the growing demand from enterprises.
- The PoA 2.0 uses a dual consensus model, which gives users the flexibility to choose different levels of security for their transactions.
The chief scientist of the VeChain Foundation, Peter Zhou, has explained in a new article on Medium why VeChain needs to introduce a revised consensus algorithm and how it works. The new consensus algorithm called SURFACE or Proof of Authority (PoA 2.0) was already presented in February in a research paper. Via Twitter, Zhou wrote yesterday that the new article should give the VeChain community a better understanding:
Communicating our research work to #VeFam is extremely important to me. That’s why Dr. Ren and I have written another article about PoA 2.0. Our goal is to allow EVERYONE to understand why we need it, how we designed it and what’s great about it.
Commenting on the motivation for the introduction of Proof of Authority 2.0, Zhou said that the introduction is primarily motivated by the growing demand for the VeChainThor blockchain.
However, as applications and businesses running on the VeChainThor public blockchain thrive, there is an ever growing demand for better preformance (higher TPS and faster transaction confirmation) and uncompromised security to empower business innovations within VeChain’s ecosytesm.
The best of both worlds: VeChain’s new consensus algorithm
However, the requirements, performance and safety described by Zhou are in direct competition with most existing consensus systems. As the chief scientist of the VeChain Foundation investigated, they are either designed to “perform well in a good network state but take security risks if the state deteriorates, or to provide uncompromising security in any network state but sacrifice a lot for performance”.
VeChain solves this problem with the new consensus algorithm, developed according to the design principle “hope for the best and prepare for the worst”. To ensure both a high-performance network under the desired conditions and uncompromising security under undesirable conditions, VeChain relies on a dual consensus model. Specifically, the PoA 2.0 uses the Nakamoto and Byzantine Fault Tolerance (BFT) consensus. Zhou describes the approach as follows:
pecifically, we attempt to achieve the near optimal performance for the Nakamoto consensus (hope for the best) when the network condition is good (meaning messages between nodes can be received in time); and utilize an asynchronous BFT mechanism to guarantee uncompromised security (prepare for the worst) when the network condition is bad (meaning the communications among nodes could be blocked due to extreme situations like natural disasters or malicious attacks).
In detail, Zhou explained that research with Oxford University has shown that the fork rate is the single largest factor affecting the performance of the Nakamoto consensus mechanism. To solve this problem, SURFACE is introducing a committee to approve the new block generated in each consensus round. This significantly reduces the likelihood of a fork compared to the classic Nakamoto consensus algorithms where the proposed block is decided by only one node, Zhou said.
The BFT consensus, on the other hand, is designed to prepare the VeChainThor blockchain for the “worst”, such as a strong partitioning of the network or a massive DDOS attack. To this end, VeChain introduces an asynchronous BFT algorithm that gives block finality to the system and coexists with the committee’s Nakamoto Consensus rather than replacing it.
Ultimately, the dual-consensus model gives users the flexibility to choose different levels of transaction security according to their actual needs, Zhou stated:
With such a dual-consensus mechanism, a transaction will be first confirmed within a rather short time (e.g., less than 1 min), and then finalized after a longer period (e.g., 5 mins). Users could use confirmed transactions for their daily usage as it is at least as secure as other blockchains using Nakamoto consensus (like Bitcoin or Ethereum). They can also wait for a longer time till the transactions are finalized if absolute security is required.
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