Different Types of Consensus Mechanisms: A Detailed Overview

Blockchain is often considered complex. But the fact is, it is a shared network where multiple nodes must agree on the same data. Every operation in blockchain technology is validated and gets approval from a group of participants, as it lacks a central authority.

Here is where the consensus mechanism comes into action. Consensus mechanisms act as the validation engine of the blockchain network. The consensus mechanism ensures that all participants stick to the rules and accept only one correct version of the data.

With the right consensus mechanism, a blockchain network can operate accurately and can prevent data manipulation activities. This helps in maintaining the integrity of the blockchain platform. This blog helps you understand the consensus mechanism and the different types of consensus mechanisms followed by blockchain platforms.

What is a Consensus Mechanism?

A consensus mechanism is a system of nodes programmed to agree that the blockchain data is the correct one, keeping decentralized networks secure. It is a protocol bringing all the nodes of the distributed blockchain network into agreement, which acts as a verification method for transactions.

5 Main Types of Consensus Mechanisms

There are different types of Consensus Mechanisms, each having its own advantages and disadvantages. Every blockchain platform adopts a suitable consensus algorithm and works to maintain its security and integrity.

Let’s look into the different types of consensus algorithms and their working mechanism.

1. Proof of Work

Proof of Work was the first established consensus algorithm, which was introduced by the Bitcoin blockchain platform. This algorithm is suitable for securing larger blockchain networks.

How it works:

• The Proof of Work involves solving complex mathematical puzzles by the network participants, called miners.
• The first one to solve the mathematical puzzle gets the opportunity to create a new block on the blockchain platform and, in return, receives a reward in cryptocurrency.
• The new block is created when all other nodes accept the verification.

Advantages:

• Highly secure due to computational difficulty.
• It is a well-established consensus algorithm with proven security measures.
• The Proof of Work algorithm is transparent and verifiable by all participants.
• No pre-existing stake is required to participate.

Disadvantages:

• This approach consumes high energy due to its complex computational puzzles.
• It requires high hardware costs and specialized equipment.
• The transaction speed is slower due to complex computation.
• The block creation time in PoW is high.

Proof of Work adopted blockchain platforms:

The Bitcoin, Dogecoin, and Litecoin blockchain platforms have adopted the Proof of Work consensus mechanism.

2. Proof of Stake

Proof of Stake was introduced to overcome the limitations of the Proof of Work consensus mechanism. Unlike Proof of Work, Proof of Stake involves validators who stake their cryptocurrency as collateral. The validators are selected based on the volume of cryptocurrency they stake as collateral.

How it works:

• The Proof of Stake consensus mechanism involves validators who approve the block proposal.
• The validators stake their cryptocurrency as collateral, and the validator proposes a new block and earns cryptocurrency as a reward.
• The block created by the validator will be checked by other validators for its validity.
• If the valuators act dishonestly, then their stakes will be partially or completely seized.

Advantages:

• Less energy consumption compared to Proof of Work.
• The transactions are faster
• The rewards are based on the stake amount of the validator
• It has a faster block creation time.

Disadvantages:

• It is difficult for new validators to establish themselves.
• Richer participants have more influence in PoS
• It requires initial capital to participate in block validation.

Proof of Stake adopted blockchain platforms:

The Ethereum 2.0, Cardano, Polkadot, and Solana blockchain platforms have adopted the Proof of Stake consensus mechanism.

3. Proof of Authority

Proof of Authority is commonly used in private blockchains where the validators are known. This approach uses the reputation and identity of the validators.

How it works:

• The Proof of Authority involves validators for creating a block.
• The validators stake financial capital and their reputation to create a block on the blockchain platform.
• Validators take turns in a sequential manner for block creation.
• If the validator behaves dishonestly, they can be legally charged and might also lose their capital and reputation.

Advantages:

• Proof of Authority requires less energy, as it is considered to be energy efficient.
• The transaction speed is faster compared to other consensus algorithms.
• The validator’s identity is revealed, which allows the organization to charge legally if the validator behaves dishonestly.
• The Proof of Authority consensus mechanism is more secure as it reveals the identity of the validator.

Disadvantages:

• Only designated validators can create blocks, resulting in a highly centralized approach.
• It is not suitable for a completely decentralized system.
• This approach requires trust in the authorities.
• The anonymity is broken as the validator's identity is revealed.

Proof of Authority adopted blockchain platforms:

The VeChain, Polygon, and Ethereum Test Networks platforms have adopted the Proof of Authority consensus mechanism.

4. Delegated Proof of Stake

Delegate Proof of Stake is an updated version of the Proof of Stake consensus mechanism. Instead of all token owners becoming the block validators, a voting system is followed to select a smaller set of delegates to validate the block on behalf of others.

How it works:

• Token holders vote for delegates, who in turn validate the blocks.
• The delegates receive rewards for validating blocks on the blockchain network.
• Token holders have the right to remove delegates from validators if they behave dishonestly.

Advantages:

• Delegated Proof of Stakes requires fewer computational requirements.
• It is more democratic when compared with PoS.
• The block creation time is faster.

Disadvantages:

• Voting out delegates can create instability in the block creation.
• Delegated Proof of Stakes requires the participation of active token holders.
• The voting system in DPoS can lead to centralization.

Delegate Proof of Stake adopted blockchain platforms:

The Cosmos, Tezos, and Polkadot blockchain platforms have adopted the Delegated Proof of Stake consensus mechanism.

5. Practical Byzantine Fault Tolerance

Practical Byzantine Fault Tolerance is a secure consensus algorithm that has been designed to withstand dishonest block validators. The block is created when the agreement is ⅔ from honest nodes.

How it works:

• A new block is proposed from the primary node.
• All other nodes communicate to validate the block.
• The block is created if ⅔ of the nodes agree and the block is finalized and added on the blockchain platform.

Advantages:

• It can validate transactions quickly.
• A practical Byzantine Fault Tolerance consensus algorithm can tolerate up to ⅓ of the malicious nodes.
• No staking of cryptocurrency is required in this approach.
• This consensus algorithm is very secure.

Disadvantages:

• The practical Byzantine fault tolerance is technically complex, thereby it is difficult to implement correctly.
• The communication between the validators is complex
• They are susceptible to Sybil attacks when there are more dishonest nodes than honest nodes. Their susceptibility can manipulate the chain.

Practical Byzantine Fault Tolerance adopted blockchain platforms:

The Hyperledger Fabric and some permissioned blockchain platforms have adopted the Delegated Proof of Stake consensus mechanism.

Other Types

1. Proof of Importance

Proof of Importance consensus algorithm uses a metric method to validate the importance of the validator in creating a block. The importance score depends on how much cryptocurrency the validator holds, the transaction activity conducted in the last 30 days, and the transaction partner. If the validator has a higher importance score, then that person is allowed to create the block on the blockchain platform. The Proof of Importance consensus mechanism is highly secure, but it is highly complex as it requires the calculation of an importance score.

2. Proof of Elapsed Time

The Proof of Elapsed Time consensus algorithm works by assigning a random waiting time for each validator. The validator whose waiting time expires first gets the right to validate and create a new block on the blockchain network. This approach is mainly adopted by permissioned or private blockchain platforms.

3. Proof of Weight

The Proof of Weight consensus algorithm works by measuring the amount of assets and tokens a validator holds. The amount of assets and tokens owned by the validator is termed as weight. Based on the weight of the holdings and their willingness to lock up as collateral, the validator for creating a new block is chosen.

Consensus Algorithm Comparison Table

Bottom Line

The evolution of consensus mechanisms has shown a significant growth of blockchain technology. It remains the validation method before creating a block on the blockchain network. Various consensus mechanisms offer distinct features, which determine the security, scalability, and speed of the blockchain platform.

Each and every consensus algorithm operates uniquely to ensure the security of the decentralized blockchain platforms without relying on a central authority. Gaining knowledge of these algorithms is vital before selecting the blockchain platform for a specific application.

Consensus Algorithm: Enabling trust across decentralized systems.

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