A security architect is designing a new payment gateway system that requires extremely high availability and fault tolerance, even in the event of compromised or malicious nodes. The system must ensure that all transactions are processed correctly and consistently, even if a minority of nodes in the distributed network fail or behave maliciously. Which consensus mechanism is BEST suited for achieving this Byzantine fault tolerance?

Why the other options are wrong

• A. Paxos is a consensus algorithm that tolerates crash failures (nodes fail by stopping) but is not designed to tolerate Byzantine faults (malicious or arbitrary behavior).
• B. PoW (e.g., Bitcoin) is a Byzantine fault-tolerant consensus mechanism but is designed for public, permissionless blockchains and suffers from low transaction throughput and high latency, unsuitable for a high-performance payment gateway.
• C. PoS is another Byzantine fault-tolerant consensus mechanism for blockchains, but like PoW, it's typically used in public, permissionless settings and may not offer the deterministic finality and speed required for a payment gateway.