CHAPTER 3

Consensus Models in Blockchain

Introduction

Consensus means a general agreement or a maj ority of opinion between a

number of subj ects. In a blockchain network, consensus refers to the

process where the distributed nodes agree on the history and the final state

of the data on the ledger, usually referred to as distributed consensus. All

participants in the network hold the data and can be a part of the decision-

making process. In order for the replication to be done uniformly, every

new block that gets added to the blockchain needs to be agreed upon

according to the defined protocol.

A consensus mechanism is used in order to avoid a central authority that

keeps track of all accounts. A fault-tolerant mechanism is useful in record-

keeping in blockchain systems to achieve agreement on a single state of the

network among distributed processes, such as cryptocurrencies.

A consensus model is needed in each blockchain as blockchains are

distributed systems sharing a common state, and so, the network has to

agree on the content of the distributed ledger, ensuring that the next block in

the chain is the one and the only version of the truth.

Structure

In this chapter, the following topics will be covered:

Consensus models—

algorithm, mechanism, and method

Algorithms of consensus

Consensus models protocol names

Mechanism of consensus

Method of consensus

Consensus model proof of work