Blockchain Consensus

Abstract

Blockchain consensus is the core element of a blockchain, which ensures the integrity and consistency of the blockchain data. Blockchain being a distributed system, in the first instance, it may appear that we can apply traditional distributed consensus protocols, such as Paxos or PBFT, to address the agreement and total order requirements in a blockchain. However, this can only work in consortium chains where participants are known and limited in number. In public chains, traditional consensus protocols cannot work due to the permissionless environment. However, in 2008 a new class of consensus algorithms emerged which relied on proof of work to ensure random leader election who wins the right to append to the blockchain by solving a mathematical puzzle. This is the so-called Nakamoto consensus protocol. This algorithm for the very first time solved the problem of consensus in a permissionless public environment with many anonymous participants.