SoK: Auditability and Accountability in Distributed Payment Systems

Abstract

Enforcement of policy regulations and availability of auditing mechanisms are crucial building blocks for the adoption of distributed payment systems. In this work we review a number of existing proposals for distributed payment systems that offer some form of auditability for regulators. We identify two major distinct lines of work: payment systems that are not privacy-preserving such as Bitcoin, where regulation functionalities are typically tailored for organizations controlling many accounts, and privacy-preserving payment systems where regulation functionalities are typically targeted to user level. We provide a systematization methodology over several axes of characteristics and performance, while highlighting insights and research gaps that we have identified, such as lack of dispute-resolution solutions between the regulator and the entity under audit, and the incompatibility of ledger pruning or off-chain protocols with regulatory requirements. Based on our findings, we propose a number of exciting future research directions.