Overview of Major Blockchain Consensus Algorithms and Their Pros and Cons

Consensus algorithms are the foundation of all blockchain and DAG platforms, serving as the most critical component that enables distributed trust without a central authority.

1. Proof of Work (PoW)

Advantages:

Field‑tested since 2009 and remains stable.

Disadvantages:

Slow transaction throughput.

High energy consumption and environmental impact.

Vulnerable to economies of scale.

Users: Bitcoin, Ethereum, Litecoin, Dogecoin, etc.

Type: Competitive consensus.

PoW was first described by Satoshi Nakamoto to achieve trust‑less distributed consensus and solve double‑spending. Miners solve a computationally intensive but purposeless puzzle to add a block, thereby staking hardware resources that would be lost if they attempted to attack the network.

Essentially, this forces miners to invest capital/resources, aligning their incentives with the health of the blockchain.

The difficulty adjusts to keep block times constant; the longest chain is accepted as valid, assuming >50% of mining power is honest.

Further reading: Proof of Work

2. Proof of Stake (PoS)

Advantages:

Energy‑efficient.

Attacks are more costly for adversaries.

Less affected by economies of scale.

Disadvantages:

Stake‑irrelevant issues (e.g., “nothing‑at‑stake”).

Users: Ethereum (upcoming), Peercoin, Nxt.

Type: Competitive consensus.

PoS replaces mining with ownership of coins; holding 10 % of the supply gives roughly a 10 % chance to forge the next block. It reduces the massive electricity consumption of PoW—one Bitcoin transaction can power 1.57 US households for a day.

此外，攻击PoS系统比攻击PoW系统更昂贵。引用Vlad Zamfir

In PoS, a 51 % attack costs the attacker the value of the staked coins, unlike PoW where hardware can be destroyed without losing the underlying currency.

Further reading: Proof of Stake

3. Delayed Proof‑of‑Work (dPoW)

Advantages:

Energy‑efficient.

Improved security by anchoring to a stronger chain.

Allows other blockchains to inherit Bitcoin’s security without paying Bitcoin transaction fees.

Disadvantages:

Only works with PoW or PoS parent chains.

Complex node calibration required in “Notary Active” mode.

Users: Komodo

Type: Collaborative consensus.

dPoW is a hybrid method where a set of notary nodes embed the hash of a block from the primary chain into a secondary, more secure chain (e.g., Bitcoin). Compromise requires attacking both chains, dramatically raising the cost of attacks.

Komodo uses 64 notary nodes selected by stakeholders; each notarized block is also recorded in a Bitcoin transaction signed by 33 notaries, creating a verifiable dPoW hash on the Bitcoin ledger.

Further reading: Delayed Proof‑of‑Work

4. Delegated Proof‑of‑Stake (DPoS)

Advantages:

Energy‑efficient.

High throughput; EOS achieves ~0.5 s block time.

Disadvantages:

Some centralization.

Risk of malicious delegates voting themselves into power.

Users: BitShares, Steemit, EOS, Lisk, Ark

Type: Collaborative consensus.

Stakeholders elect a limited number of witnesses (e.g., 21 in EOS) to produce blocks in a round‑robin fashion. If a witness fails or behaves maliciously, stakeholders can replace it quickly, maintaining network liveness and security.

Further reading: Delegated Proof‑of‑Stake

5. Proof of Authority (PoA)

Advantages:

Energy‑efficient.

Fast block finality.

Disadvantages:

More centralized; typically used in private or permissioned blockchains.

Users: POA.Network, Ethereum Kovan testnet, VeChain

Type: Collaborative consensus.

In PoA networks, pre‑approved accounts (authorities) sign blocks. Validators run software that automatically creates blocks without constant human oversight, but the authority nodes must remain secure and reputable.

Further reading: Proof of Authority