The main consensus protocols

The blockchain consensus protocols create an irrefutable system of agreement between different parties within a distributed network, while preventing malicious exploitation of the system. Let’s discover together how these protocols work and how they differ from one system to another.

Definition of a consensus protocol

Blockchain consensus protocols ensure synchronization between all network nodes. Each consensus aims to answer a specific question: how can we ensure the authenticity of each transaction? Any individual can submit information and decide to store it on a blockchain. It is therefore essential to be able to review this information and decide by consensus whether or not it is possible to add it to the network.

The term “consensus” means that all nodes in the network must agree on an identical version of the blockchain. Somewhere the mechanism of consensus of a blockchain is an internal and automatic audit of its network. This protocol is therefore essential and has two functions:

  • It allows the blockchain to be updated while ensuring that each chain block is valid. People participating in block validation (referred to as network “nodes”) must have an incentive to engage in network security, which usually takes the form of a monetary reward.
  • He prevents only one and same entity can control the entire network and thus guarantees its decentralization.

The rules of a consensus protocol

A blockchain consensus follows specific rules. Network nodes shall ensure that each block and each transaction meets a certain number of criteria before it can be validated. Each data must receive the unanimous acceptance of all the nodes of the network in order to be validated.

The main objective of consensus protocols is to be able to fight against attacks that jeopardize the security of the network. A very common example of an attack is that of double-expense, or double-spending. It consists of issuing two transactions that spend the same credit. The role of the consensus is then to decide which of its two transactions can be considered as validated and which must, conversely, be canceled.

The main blockchain consensus mechanisms

The consensus of a blockchain is defined from its creation by its founders. The most famous and the first of these is the proof of work (Proof-of-Work in English), which uses the Bitcoin protocol.

Proof-of-Work (PoW), or proof of work

The Proof-of-Work protocol is the most widely used of all blockchain consensuses. Since 2009, it has been able to demonstrate its resistance and security to various attempted attacks.

In the Proof-of-Work protocol, the different network nodes are called minors. To confirm a transaction, miners must solve a complex mathematical problem requiring significant computing power.

To do this, they use a mathematical process called a hash function. Hashing is used to write transaction data into blocks and connect them together. There are different types, such as SHA 256, used on Bitcoin. Once the hashes registered in the blockchain, it is tamper-proof.

A miner is rewarded for each block they manage to approve and confirm. Its income is proportional to the computing power it is able to deploy to solve the problem.

To learn more about the subject, we invite you to read our detailed definition of the protocol Proof-of-Work.

Proof-of-Stake (PoS), or proof of stake

Proof-of-Stake, or proof of stake, is based on a completely different logic than proof of work and does not require any particular computing power. In the Proof-of-Stake, consensus participants can be likened to shareholders of a business entity having the privilege of participating in its consensus mechanism.

PoS is a consensus that is much less expensive than PoW, because it requires neither energy expenditure nor special hardware. Concretely, to validate a block, the nodes must here prove their possession of a certain amount of cryptocurrency, and pawn it on the network. The larger this quantity, the more likely a node will be chosen to update a blockchain’s ledger. The PoS consensus considers that these people are the most likely to want to fight against a network attack, which could completely ruin them.

Find more details about the Proof-of-Stake by reading our article dedicated to the question.

The Delegated Proof of Stake (DPoS), or delegated proof of stake

Emerging more recently, the Delegated Proof-of-Stake tends to respond to the weaknesses of PoS and PoW by offering a hybrid model.

DPoS consensus works on the same basic principle as PoS. However, people in charge of forging blocks must be elected by community members. The system of elections ensures that the blockchain is not controlled by a minority of people, as may be the case of a miner with a lot of computing power, or a PoS forger with a very large amount of tokens.

Lisk is a very good example of a DPoS protocol. Its blockchain provides for the election of 101 delegates responsible for the consensus mechanism. These delegates are elected by the holders of lisk tokens, and must pay back to the voters a part of their winnings.

The DPoS protocol has many advantages, but also some disadvantages. To find out more, we invite you to read our article dedicated to the explanation of the Delegated Proof of Stake.

Many consensuses

The Proof of Work, Proof of Stake and Delegated Proof of Stake are the main blockchain consensus. There are many others.

Among the interesting consensuses, we can note the Proof of Importance blockchain spring roll. Each node has an importance score. His importance score determines how often he can forge XEM. The importance of a node depends on how long it has had tokens, but also on its contribution to the network: the more a node sends transactions to other users and uses the network, the more important it becomes. An interesting logic for create a living and dynamic blockchain.

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The main consensus protocols

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