Verifier Non-Locality in Interactive Proofs

TL;DR

This paper reveals that in multi-prover interactive proofs, the verifier can inherently act as a non-local resource, significantly impacting the understanding and design of such protocols.

Contribution

It introduces the novel concept that the verifier's role includes providing non-local resources, challenging previous assumptions in multi-prover proof systems.

Findings

Verifier can serve as a non-local resource in proofs

Existing soundness proofs assume verifier is not non-local

Non-locality of verifier affects protocol security and analysis

Abstract

In multi-prover interactive proofs, the verifier interrogates the provers and attempts to steal their knowledge. Other than that, the verifier's role has not been studied. We have discovered that the verifier plays a much more important role than previously thought. Simply put, the verifier has the capability of providing non-local resources for the provers intrinsically. Existing MIPs' proofs of soundness implicitly depend on the fact that the verifier is not a non-local resource provider. The verifier's non-locality is a new unused tool and liability for protocol design and analysis.