Consensus mechanisms (also known as consensus protocols or consensus algorithms) allow distributed systems (networks of computers) to work together and stay secure.
For decades, these mechanisms have been used to establish consensus among database nodes, application servers, and other enterprise infrastructure. In recent years, new consensus mechanisms have been invented to allow crypto-economic systems, such as Ethereum, to agree on the state of the network.
A consensus mechanism in a crypto-economic system also helps prevent certain kinds of economic attacks. In theory, an attacker can compromise consensus by controlling 51% of the network. Consensus mechanisms are designed to make this “51% attack” unfeasible. Different mechanisms are engineered to solve this security problem in different ways.
Types of Consensus Mechanisms
They have a different kind of algorithms and work with different principles
- Proof-of-work (PoW)- This is the mechanism that allows the decentralized network to come to a consensus, or agree on things like account balances and the order of transactions. This prevents users from “double spending” their coins and ensures that the blockchain is tremendously difficult to attack or manipulate.
- Proof of stake (PoS) — This is a type of consensus mechanism used to validate cryptocurrency transactions. With this system, owners of the cryptocurrency can stake their coins, which gives them the right to check new blocks of transactions and add them to the blockchain. This method is an alternative to proof of work, the first consensus mechanism developed for cryptocurrencies. Since proof of stake is much more energy-efficient, it has gotten more popular as attention has turned to how crypto mining affects the planet.
- Proof of capacity (PoC) — This is a consensus mechanism algorithm used in blockchains that allows mining devices in the network to use their available hard drive space to decide mining rights and validate transactions. This is in contrast to using the mining device’s computational power (as in the proof of work algorithm) or the miner’s stake in the cryptocurrencies (as in the proof of stake algorithm).
- Proof-of-activity (PoA) — This is a blockchain consensus algorithm used in cryptocurrencies and similar systems. It is used to ensure that all transactions occurring on the blockchain are genuine, as well as to ensure that all miners arrive at a consensus. PoA is a combination of two other blockchain consensus algorithms: proof-of-work (PoW) and proof-of-stake (PoS).
- Proof-of-burn (PoB) -This is a blockchain consensus mechanism with minimal energy consumption, compared to proof-of-work (PoW). Decentralized platforms employing the PoB method ensure miners reach a consensus by burning coins. Burning is the process of permanently eliminating cryptos from circulation. Although the practice reduces inflation, PoB-powered blockchains use it to validate transactions.
- Proof of elapsed time (PoET) — This is a consensus mechanism often used on permissioned blockchain networks to decide the mining rights or the block winners on the network. Permissioned blockchain networks are types that require any would-be participant to identify themselves before they are allowed to join.
- Delayed Proof of Work (dPoW) — This is a security mechanism designed by the Komodo project. It is basically a modified version of the Proof of Work (PoW) consensus algorithm that makes use of Bitcoin blockchain’s hashpower as a way to enhance network security.
Pros and Cons of Consensus Mechanism
- Forms agreement foundational to the crypto-market: Consensus mechanisms synchronize data between all participating users and enable trust in a blockchain.
- Creates a secure environment: Cryptocurrencies and distributed applications rely on consensus mechanisms for security.
- Anyone can participate: With the most popular consensus mechanisms, barriers to participating as a miner or operating their own nodes are not very high.
- May be energy-intensive: Proof-of-work is extremely energy-intensive and requires as much electricity as many countries.
- Potential for attacks: There’s a small chance for a type of hack called a 51% attack, among other minor weaknesses.