A security architect is designing a new blockchain-based settlement system for inter-bank transactions. The system requires high fault tolerance and consistency, even if some nodes in the distributed network act maliciously or fail. The solution must ensure that all legitimate nodes agree on the order and validity of transactions with high throughput. Which consensus algorithm would be MOST suitable for this requirement?
- AProof of Work (PoW)
- BDelegated Proof of Stake (DPoS)
- CPractical Byzantine Fault Tolerance (PBFT)
- DProof of Stake (PoS)
Show answer & explanationAnswer & explanation
Correct answer: C. Practical Byzantine Fault Tolerance (PBFT)
Practical Byzantine Fault Tolerance (PBFT) is a consensus algorithm that is highly suitable for permissioned blockchain networks where participants are known and trusted, such as inter-bank systems. It provides strong consistency and fault tolerance against malicious (Byzantine) nodes, offering high transaction throughput and low latency, which are critical for financial settlement systems. PoW and PoS are typically used in public, permissionless blockchains and have lower throughput.
Why the other options are wrong
- A. PoW is used in public blockchains (like Bitcoin) and is not suitable for high-throughput, low-latency permissioned systems due to its probabilistic finality and resource intensity.
- B. DPoS is a variant of PoS that uses delegates to validate transactions, still primarily for public blockchains, and would not meet the stringent consistency and fault tolerance requirements of a regulated financial system as effectively as PBFT.
- D. PoS is also for public blockchains, offering better energy efficiency than PoW but still generally lower throughput and higher latency than PBFT for enterprise use cases.
Practical Byzantine Fault Tolerance (PBFT)
Practical Byzantine Fault Tolerance (PBFT) is a consensus algorithm that provides high consistency and fault tolerance against malicious (Byzantine) nodes in a permissioned distributed system.
- Suitable for permissioned blockchains (known participants).
- Offers deterministic finality, high throughput, and low latency.
- Can tolerate up to (N-1)/3 faulty nodes, where N is total nodes.
Memory trick: PBFT: Private, Byzantine-tolerant, Fast Transactions.