Cryptographic Techniques for AI Safety via Debate

AI debate aims to let a weak judge evaluate stronger AI systems by having competing agents expose each other’s errors. We study two mechanisms for strengthening debate: cryptographic commitments and private communication. Building on classical competing-prover protocols, we give debate protocols whose communication and judging costs scale polylogarithmically with computation length, in addition to input and security-parameter costs. These guarantees extend the standard debate model from PSPACE to EXP and accommodate black-box calls to tools, databases, or human feedback. With cryptographic commitments and random access to the input and transcript, the judge checks only a constant number of locations and makes at most one black-box call. We evaluate private communication in LLM debates where the agent defending an incorrect answer is stronger than its opponent and the judge; experiments show that privacy in debate can increase the protocol's accuracy and its robustness.