Multi-Prover Interactive Proofs: Unsound Foundations.

Abstract

Several Multi-Prover Interactive Proofs (MIPs) found in the literature contain proofs of soundness that are lacking. This was first observed [1] in which a notion of Prover isolation is defined to partly address the issue. Furthermore, some existing Zero-Knowledge MIPs suffer from a catastrophic flaw: they outright allow the Provers to communicate via the Verifier. Consequently, their soundness claims are now seriously in doubt, if not plain wrong. This paper outlines the lack of isolation and numerous other issues found in the (ZK)MIP literature. A follow-up paper will resolve most of these issues in detail.