Foreword
Hello, this is Volare. Today, we’re going to briefly introduce the core of the Volare network, the consensus algorithm. In addition to explaining the pBFT method, we will explain what kind of consensus method Volare has developed to create a blockchain for commercial services.
pBFT (Practical Byzantine Fault Tolerance)
Like PoW and PoS, pBFT is a Byzantine Fault model, but it solves the uncertainty and performance problems of the finality. First, to explain the Byzantine general’s problem, assume there is a ’n’ number of Byzantine generals each heading a unit of troops surrounding the enemy city. One general can communicate with other n-1 numbers of generals only by sending a messenger to each general. The generals now have to come to an agreement on whether to launch a decisive full-scale attack or wait a little longer. But there may be traitors among the generals, and traitors can give any baseless opinion with the intention to distract. We need an algorithm to agree to make a decision to attack and avoid intentional distraction from the betraying generals. The overall pBFT process is as follows:
First, the client broadcasts a request to all nodes. The Leader becomes the Primary and passes commands sequentially to other nodes. When each node receives a broadcast command, it replies to all nodes, including the Leader. Each node retransmits the received signal to all nodes, including the Leader, when it receives more than a certain number (2n) of the forwarded commands. When each node receives more than a certain number of commands (2n), it executes the command and registers the block to return a replay message to the client.
Unlike PoW and PoS, blockchain branching does not occur in pBFT because a block is made after making a decision by a majority vote. Therefore, the finality can be secured because the block is not altered once it is confirmed. pBFT also operates very fast because, unlike in PoW, it does not have to repeat the calculation until the conditions are satisfied. Even if you want to cheat, you have to win a majority vote, and if a Byzantines lies, if all participants monitor the leader’s movements and decide it’s a lie, participants can apply for a leader replacement by a majority vote. This is why pBFT is a strong failure-resistant algorithm.
Volare Consensus
In the Volare network, we use a consensus model of Equilibrium called Equalize, which is an improved version of pBFT. Equalize is composed of largely four stages: Networking, Propose, Vote, and Commit.
In the networking phase, StageInfo is exchanged between Equalizer nodes, which are Validator nodes. StageInfo is composed of the height of the newly created block, the current round, and the previous block hash for each node. Nodes merge StageInfo of themselves and other nodes to determine the StageInfo for the entire network. Nodes that have the same StageInfo begin to participate in the agreement. All nodes use a round-robin approach based on stake through StageInfo to decisively determine the next block proposer and enter the next step.
The Propose phase is the process of propagating transactions for an agreement. The selected block proposer merges the transactions in the mempool into one proposal and delivers them to all nodes participating in the agreement.
In the Vote stage, the transactions are verified and voted on the proposal proposed by the proposer. A Merkle tree and a transaction root hash are created for a proposal originated from a valid proposer. When the transaction verification is complete, the nodes sign the proposal with their private keys, adding a hash to the transaction root and propagating it to other nodes involved in the agreement. Each Equalizer node evaluates the offer as valid if it has more than 2/3 of the total votes and confirms the block.
In the commit stage, as shown in the figure below, the blocks determined in the Vote stage are reflected in the database, recorded in the blockchain, and state transformation occurs. Committed blocks will not be branched and will be guaranteed finality in Equilibrium forever.
In the manner described above, the Equilibrium consensus algorithm used in the Volare Network significantly reduces the time to create blocks by eliminating inefficient computation processes that arise from competitive algorithms. In addition, when more than a certain number of blocks are stacked, the block is not confirmed probabilistically and instead confirmed immediately through voting, thereby reducing the time required to determine the block. The traditional pBFT consensus approach allowed each verifier node to propagate a bundle of transactions to the next block proposer, which resulted in reduced traffic to improve the overall system processing speed. Additionally, the networking data contained in the exchange of current status per node and the exchange of votes in the network was simplified to reduce communication overhead, thereby further improving system processing speed.
Summary
Volare Network is a blockchain platform that enables computational speed comparable to conventional financial systems of existing industries by realizing a speed of 4,500 tps and a block generation and confirmation time of less than 3 seconds through Equilibrium’s consensus engine. We’ve also taken into a consideration a number of other factors for commercial utilization, including storage and reliability. Equilibrium engine supports a storage optimization module to respond to storage issues that may arise from high speed, and a network traffic optimization module that secures stability according to varying system speeds. As a result, Equilibrium engine has evolved into a high-performance blockchain engine capable of supporting not only financial systems but also various commercial services such as games, platforms, marketplaces, and funding.
Reference
Bitcoin: A Peer-to-Peer Electronic Cash System
