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The Definition of Consensus in Blockchain

BitForex Editor
Sep 29, 2020

Blockchain is a public distributed ledger system that is poised to tackle all the problems encountered by regular centralized systems. However, what many people fail to understand is Blockchain functions through a series of definitive rules. Hence it is a challenge to accept data or information that does not sync with its original alignment. One of the biggest problems is the Byzantine Generals problem.

Now, this is where consensus comes in – in layman terms, a consensus is a decision taken by some group of people in a community that is beneficial to the community. In Blockchain, a consensus mechanism is a procedure that all the individual entities of the Blockchain must follow to ensure the proper functioning of the block.

What Is Consensus In Blockchain?

Blockchain is a decentralized (keyword – decentralized) distributed ledger system with no authoritative command center. For example, in a centralized computer system, a database holds all the necessary information to ensure that the system functions well. That is input and updates made into the system must follow certain commands already on the computer.

The consensus allows for Blockchain to remain an efficient, reliable, and secure dynamic system to ensure all transactions on the network are genuine and acceptable based on the consensus. Finally, this protocol allows participants to find a common agreement that works for the entire Blockchain system.

Why Is The Consensus Needed In Blockchain?

Bitcoin has remained the most successful Blockchain system because of its ability to reach a consensus with its community. However, you must realize that it was not the first decentralized peer-to-peer currency system. These other systems could not reach a consensus – a problem known as the Byzantine Generals.

Now, let’s explain the issue to you.

Assuming the Byzantine Generals is planning to attack a city with a huge army. They will only win if they have a commander with a solid plan and if all the generals attack at once. That means everyone must be in on the tactics and work accordingly. The Byzantine Generals problems are better to explain in a Microsoft Research presented by a team of researchers in 1982 below.

What Consensus Protocols Are Available On Blockchain?

Practical Byzantine Fault Tolerance Algorithm

The Practical Byzantine Fault Tolerance Algorithm or PBFT was designed and introduced by Barbara Liskov and Miguel Castro in the 90s. It was a solution in form of an allegory to counteract the Byzantine Generals' problem in the Blockchain. This solution applicable to a distributed ledger system enables Blockchain to reach a consensus on the same value even if all the modes in the network are not in agreement or do not respond on the same level. The PBFT protects the system against failure by engaging in a collective decision to minimize the problems caused by faulty nodes.

A better explanation of the Byzantine Generals' problem was seen in a Microsoft research presented by Leslie Lamport, Marshall Pease, and Robert Shostak in 1982. You can read more on the thought of how Byzantine Generals affect the overall workings of the Blockchain and its components.

However, since it was published, many people have come up with different ways to solve the problems caused by the Byzantine Generals on Blockchain. One primary solution was the PBFT or the Practical Byzantine Fault Tolerance. However, this solution proved to be too weak for a decentralized ledger system like Blockchain.

Below are some solutions that are been used but may differ as to the transaction move from one block to another.

Proof of Work- PoW

This is the most commonly used consensus found in the bitcoin Blockchain that uses hash functions to verify transactions across the modes. This algorithm requires that participants must prove that they deserve the right to add new blocks to the Blockchain by the work done and delivered. However, the process is tedious, time, and energy-consuming hence not the most efficient in dealing with Byzantine generals.

Proof of Stake-PoS

Due to the high energy and time consumed by bitcoin miners, there was a need to suggest a more affordable solution to tackle the issue. Proof of stake was the alternative algorithm that probed ownership of stake through a simple digital signature. The downside was this system encourages saving crypto coins and not spending.

Proof of Burn - PoB

So in the previous algorithms, it is expensive to maintain and consumes a lot of energy and processes. The proof of burn uses a system where validators burn excess coins by sending it to an irretrievable address. This keeps the system active and working with miners getting mining privileges for their loss.

There are other consensuses like Proof of Importance, Proof of Authority, Proof of Activity, Proof or Weight, and so on, but the above are the most used. It is necessary to choose wisely which one works best for your network, as Blockchain cannot function efficiently without these consensuses. The consensus in Blockchain enables the seamless verification of every single transaction made on the block.

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