What is IPBFT? ?


What is IPBFT?

IPBFT is the consensus algorithm for INT4.0. If you compare a blockchain to a car, the consensus mechanism is the engine that powers the car.

IPBFT is a faster, more scalable, and more secure algorithm

Improving IPBFT is based on PBFT (Practical Byzantine Algorithm):

· Linear communication: IPDBFT achieves linear worst-case communication volume, in contract to PBFT’s O(n⁴)

· Random leader selection: the leader for each round in IPBFT is selected by a verifiable random function (VRF), which protects the leader from predictable attacks.

What is consensus?

The consensus mechanism is the core of distributed technology. In a decentralized environment where there is no central entity to verify transactions, the consensus protocol ensures that all participants of the network reach an agreement. The entire network verifies transactions in a completely trustless manner.

What PBFT (Practical Byzantine Algorithm)?

Practical Byzantine Fault Tolerance is a model for reaching consensus by making multiple computers behave consistently, a technique known as state machine replication.

Nodes reach a consensus on the decision by passing messages about the decision between each other-such as the validity of the block in the blockchain. In this system, security increases with the number of honest nodes. Honest nodes agree to correct decisions and reject wrong decisions made by malicious nodes, as long as the number of malicious nodes is less than one-third of the total.

pBFT systems are energy efficient; they do not require high computing resources or a lot of energy to operate. In addition, pBFTs can reach consensus quickly because all nodes are constantly communicating with each other and do not require multiple confirmations. Once the nodes agree on a decision, the transaction is complete.

This process can be simplified into four steps.

  1. pBFT uses a voting mechanism to elect a leader node in a round-robin format.
  2. The leader initiates the decision and broadcasts it to the secondary nodes.
  3. All nodes, including the leader node and the auxiliary nodes, send responses.
  4. A response is considered valid when ⅔ + 1 node sends the same response.

If the leader act maliciously, it can be removed by most nodes.

IPBFT consensus versus PBFT consensus

First of all, in terms of the conditions for block production, the traditional PBFT protocol generally requires more than 2/3 of the validators to agree before the block can be produced. To ensure the consistency of the weight of stake and voting rights, IPBFT changed the block generation condition from more than 2/3 of the number of validators to 2/3 of the total number of votes to improve the speed of block generation to a certain extent. If a validator fails to produce a block, it will vote for the next round according to a certain algorithm, while the block production conditions will be relaxed, that is, the total number of votes exceeds (2/3–1/3*R/30)*V , where R is the number of rounds of the block, the maximum value of 15, V is the current total number of votes, so the number of rounds of a block if it reaches 15 rounds, the total number of votes only needs to be greater than 50% to complete the block, which greatly increase the robustness of the INT network.

Secondly, in terms of voting message broadcasting, the communication complexity of ordinary PBFT will increase with the square of the number of nodes. When the number of nodes increases to more, the communication pressure on the network will become very large. To alleviate this problem, IPBFT establishes a leader for each round of voting, collects votes from all verifiers, and uses aggregate signatures to achieve linear communication, which greatly reduces the complexity of network communication in the case of multiple nodes and laying the foundation for further decentralization of the network.

In addition, in the selection of block producers, ordinary PBFT usually adopts the way of out of blocks, while the block producers in each round of IPBFT are randomly selected by VRF. VRF is a pseudo-random generator whose output is verifiable, random and unpredictable in advance. At the same time, the overall probability of a node being selected will be positively related to its own vote weight. Therefore, the leader of each round is unpredictable, and the opponent cannot attack the leader in advance, so the entire network will be more fair and safe.

How does IPBFT work?

IPBFT uses a verifiable random function (VRF)-based password tossing lottery to randomly elect verifiers, while the node with the higher vote weight ratio will have a higher chance of getting out of the block, which will ensure greater security and fairness. In terms of on-chain governance, multiple governance parameters are introduced and a punishment mechanism for misbehavior is added. The governance parameters can be dynamically adjusted on the chain through a referendum, making the community governance process more efficient and fair.

The specific operation process is as follows:

Firstly, the system selects the outgoing node for each round through VRF, then the outgoing node will first propose the block and broadcast it to the other god’s nodes, then the consensus among the god’s nodes will be conducted through IPBFT consensus algorithm, and it needs to meet more than 2/3 of the total votes to agree in order for the block to come out properly.

Every other cycle, the god’s nodes will be re-elected based on the number of votes they have obtained, and the node with the top 25 votes will be the new round of block producers.

Every normal block will get a certain block reward. The block reward includes a fixed block reward and half of the handling fee. The other half of the handling fee will be directly destroyed. The god’s node can set a reward percentage, each block reward will be divided proportionally between the block producer and the INT holders who voted for that node.

Every INT holder can participate or propose a system referendum to decide the main affairs and development of INT, each referendum will be led by the INT Foundation after the vote is completed, and will be promoted together with the community.