SoK: Understanding zk-SNARKs: The Gap Between Research and Practice

TL;DR

This paper provides a comprehensive analysis of zk-SNARKs, bridging the gap between research and practical application by classifying existing schemes, surveying popular libraries, and offering recommendations for improved usability and standardization.

Contribution

It unifies the process of converting programs into zk-SNARKs, classifies existing schemes, surveys practical libraries, and offers actionable recommendations to bridge research and industry gaps.

Findings

Proving system is the main focus in academia.

Constraint system is a bottleneck in industry.

Virtual environment facilitates library testing and comparison.

Abstract

Zero-knowledge succinct non-interactive arguments of knowledge (zk-SNARKs) are a powerful tool for proving computation correctness, attracting significant interest from researchers, developers, and users. However, the complexity of zk-SNARKs has created gaps between these groups, hindering progress. Researchers focus on constructing efficient proving systems with stronger security and new properties, while developers and users prioritize toolchains, usability, and compatibility. In this work, we provide a comprehensive study of zk-SNARK, from theory to practice, pinpointing gaps and limitations. We first present a master recipe that unifies the main steps in converting a program into a zk-SNARK. We then classify existing zk-SNARKs according to their key techniques. Our classification addresses the main difference in practically valuable properties between existing zk-SNARK schemes. We survey over 40 zk-SNARKs since 2013 and provide a reference table listing their categories and properties. Following the steps in master recipe, we then survey 11 general-purpose popular used libraries. We elaborate on these libraries' usability, compatibility, efficiency and limitations. Since installing and executing these zk-SNARK systems is challenging, we also provide a completely virtual environment in which to run the compiler for each of them. We identify that the proving system is the primary focus in cryptography academia. In contrast, the constraint system presents a bottleneck in industry. To bridge this gap, we offer recommendations and advocate for the opensource community to enhance documentation, standardization and compatibility.