LedgerMaze: An Efficient Privacy-Preserving Noninteractive Zero-Knowledge Scheme Over Account-Model Blockchain

Abstract

The prosperity of blockchain has pushed various decentralized applications, e.g., cross-regional finance, due to its advantages of openness, immutability, and decentralization. The feature of openness inevitably leads to a serious privacy breach. Recently, various privacy-enhanced works (e.g., Zcash, Monero) were proposed focusing on this problem. However, most existing solutions either aim for the unspent transaction output (UTXO) model, or fail to provide full privacy protection for the account-based model with efficient performance. In this paper, we put forwardLedgerMaze, an efficient privacy-preserving non-interactive zero-knowledge (NIZK) scheme over account-model blockchain. We design a novel scheme calledchequemechanism to cut the link between the sender/receiver relationship. Namely, a sender transfers money to a receiver's cheque, then the receiver can retrieve the cheque among a set of cheques for obfuscation without revealing the original one. We construct several efficient NIZK proofs for initializing the mechanism. Moreover, we further analyze the security properties ofLedgerMaze. Experimental results show thatLedgerMazeachieves comparable performance in communication and computation costs while retaining a full privacy guarantee, compared to previous similar constructions.