Byzantine Fault Tolerance for Agent Swarms
The coordination layer for autonomous agents. When your AI systems need to elect a leader, vote on decisions, or prevent conflicts — Arbiter provides the infrastructure for machines to reach agreement.
January 5, 2025
When agents don't trust each other, you need more than simple majority voting. You need Byzantine Fault Tolerance (BFT)—the ability to reach consensus even when some participants are actively malicious.
What is Byzantine Fault Tolerance?
BFT is a property of distributed systems that work correctly even when some participants behave maliciously—not just faulty ones. Named after the "Byzantine Generals Problem" in computer science, BFT systems can tolerate up to one-third of participants being malicious.
The Math
For a system to tolerate f malicious agents:
- You need n ≥ 3f + 1 total agents
- Consensus requires 2f + 1 agreeing votes
- This ensures honest agents always outnumber malicious ones
Why BFT Matters for Agent Swarms
In agent swarms, participants may be:
- Owned by different parties who don't trust each other
- Potentially compromised or hacked
- Optimizing for conflicting objectives
Simple majority voting assumes honest participants. BFT assumes adversaries and still reaches correct consensus.
How Arbiter Implements BFT
Arbiter detects and prevents Byzantine behaviors:
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Equivocation Detection
Agents that vote both "yes" and "no" are detected through cryptographic signatures and nonces.
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Invalid Signature Detection
All votes are cryptographically signed. Invalid signatures are rejected.
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Term Validation
Votes in wrong terms are rejected. Term numbers are strictly monotonic and recorded on-chain.
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Slashing
Detected Byzantine behavior creates slashing evidence that can be submitted on-chain to penalize the malicious agent's stake.
When to Use BFT Mode
Use BFT mode when:
- Agents are owned by different parties
- Security is critical
- You can tolerate the higher latency
Use simple majority mode when agents are trusted and you need lower latency.
Conclusion
Byzantine Fault Tolerance is essential for agent swarms that don't trust each other. Arbiter makes BFT accessible through a simple API, enabling secure coordination even in adversarial environments.