The Honest Quorum Problem: Epistemic Byzantine Fault Tolerance for Agentic Infrastructure

Imagine you're building a distributed system where multiple participants need to agree on the state of a shared resource, like a blockchain or a collaborative application. The challenge is ensuring that even if some participants act maliciously or fail, the system can still reach a consensus. However, current methods can still lead to situations where a group of compliant participants mistakenly endorse an incorrect state due to reasoning errors. This failure mode, termed the Honest Quorum Problem, highlights that just reaching agreement isn't enough; the agreement must also be semantically valid to ensure safety and reliability in execution. To tackle this issue, the authors propose a new model called Epistemic Byzantine Fault Tolerance (EBFT). This model enhances traditional Byzantine fault tolerance by introducing two new metrics that quantify the risk of invalid endorsements and the degradation of system liveness. By doing so, EBFT allows for a more nuanced understanding of fault tolerance in systems where participants may share common vulnerabilities. This approach shifts the focus from merely achieving consensus to ensuring that the consensus reached is both valid and safe, which is crucial for building robust distributed systems.

Introduces a new fault-tolerance model addressing semantic validity in distributed systems.

Provides a solid theoretical framework with derived conditions for quorum thresholds.