Byzantine Fault Tolerance

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Handling nodes that can behave arbitrarily (malicious or buggy), not just crash. The Byzantine Generals Problem: reaching agreement when some generals may be traitors. PBFT (Practical BFT) tolerates up to f failures with 3f+1 nodes. Used in blockchain consensus and high-security systems. Much more expensive than crash-fault-tolerant consensus.

Key Properties

  • Raft (only handles crash failures, not Byzantine)
  • Paxos (also assumes non-Byzantine failures)

distributed-systems consensus security