BCTPV-NIZK: Publicly-Verifiable Non-interactive Zero-Knowledge Proof System from Minimal Blockchain Assumptions

Non-interactive publicly-verifiable zero-knowledge proofs (PV-NIZKs) are essential to modern cryptography. However, historically, literature has used dependencies like the need for absolute trust in a third party or the existence of a truly random oracle to construct such proofs. Recently, the focus has shifted to exploiting the decentralized trust foundation of a generic Proof-of-Stake (PoS) blockchain to build such proofs. However, such proposals make unrealistic assumptions on the blockchain itself: static adversaries, assumptions on the future behavior of the players, and the existence of first-time miners in any given sequence of n honestly mined blocks. While aiding good proofs, such assumptions undermine the practical adaption of such proof systems. This paper introduces a blockchain-based PV-NIZK (BCTPV-NIZK) system from standard blockchain assumptions. It assumes the existence of a publicly-verifiable, secret randomness generation scheme (widely studied in literature and requires no further assumptions on trust).