Survey on Blockchain Consensus Strategies

Blockchain is a distributed data store that offers a trusted infrastructure for mutually distrusting parties to network and transact, eliminating the need of any central authority or third party intermediary. The trust element in blockchain is due to the tamper proof record keeping in blockchain through efficient hashed block-linking mechanism and the consensus protocol among the network peers to create any new record in the distributed ledger. The consensus mechanism in distributed data store ensures that every participant node in the network accepts on a common agreement over a transaction or state transition in a system by gathering confirmation from all or at-least majority of the members. Usually some form of voting or lottery mechanism is employed for the leader election process to implement consensus among the participants in a business network. Consensus mechanism is also responsible for the smooth functioning of the distributed network in the event of some arbitrary faults or node failures or even any malicious attacks in the network. Generally a consensus mechanism implementation is a tailored solution based on application or use case. It ensures the correctness of data in the trusted distributed ledger through the peer agreement process. In this work, we explore the evolution of state of the art consensus protocols for various blockchain implementations, their application, advantages and drawbacks as well.