Non-Interactive Zero-Knowledge for Blockchain: A Survey

Juha Partala,Susanna Pirttikangas,Tri Hong Nguyen

doi:10.1109/access.2020.3046025

Abstract

We survey the state-of-the-art non-interactive zero-knowledge argument schemes and their applications in confidential transactions and private smart contracts on blockchain. The main goal of this paper is to serve as a reference for blockchain application developers in finding the most suitable scheme for a particular use case. We give an overview and compare the state-of-the-art protocols for confidential transactions and private smart contracts regarding the protection of the transaction graph and amounts, data and functionality. However, our main focus is on state-of-the-art zero-knowledge argument schemes. We briefly describe their backgrounds, proof lengths and computational complexities and discuss their cryptographic security models. Our focus is on seminal, otherwise notable and, especially, implemented methods that are ready to be applied in practice. We also survey the existing implementations of transforming computations into circuit representations required by those methods. We note that the existing schemes have different strengths and drawbacks regarding usability, setup, proof length and proving and verification costs.

Highlights

We are increasingly dependent on services provided by smart devices and communication networks
Massive data collection has lead to security and privacy issues
Seven constructions are supported: 1) An extension to the zero-knowledge argument of Ben-Sasson et al [132] which follows the same approach as Pinocchio [64], [81] using R1CS, 2) SNARKs for problems expressed as arithmetic circuits, 3) SNARKs for problems expressible as unitary-square constraint systems [133], 4) SNARKs for Boolean circuits for the language of two-input boolean circuit satisfiability, 5) simulationextractable SNARKs based on the method of Groth and Maller [117], 6) ADSNARK [134] for efficient SNARKs on authenticated data from a trusted source, and 7) method for proof-carrying data (PCD) for recursive composition of SNARKs to extend SNARKs to the setting of distributed networks of verifiers and provers based on the method of Bitansky et al [135]

Summary

INTRODUCTION

We are increasingly dependent on services provided by smart devices and communication networks. Zero-knowledge argument schemes are going to be one of the main building blocks of privacy-preserving blockchain applications Partala et al.: Non-Interactive Zero-Knowledge for Blockchain: A Survey to assure the validity of a statement or the knowledge of secret values without disclosing any information apart from the fact that the prover knows those things Such functionality enables us to guarantee the validity of the data on the blockchain without disclosing sensitive information. In order to implement privacy-preserving applications for blockchain, developers need to be aware of the existing privacy protection and zero-knowledge schemes, their properties and suitability for different use cases. A. RELATED WORK We concentrate on zero-knowledge argument schemes for blockchain applications. For general information on the threats and challenges regarding security and privacy, we refer to the extensive work in the aforementioned surveys

BLOCKCHAIN AND PRIVACY

LOW-LEVEL TOOLS

DISCUSSION

XIII. CONCLUSION