Authors: Chao Lin, Debiao He, Xinyi Huang, Muhammad Khurram Khan and Kim-Kwang Raymond Choo
Title: DCAP: A Secure and Efficient Decentralized Conditional Anonymous Payment System Based on Blockchain
Journal: IEEE Transactions on Information Forensics and Security
Abstract: Blockchain, a distributed ledger technology, can potentially be deployed in a wide range of applications. Among these applications, decentralized payment systems (e.g. Bitcoin) have been one of the most mature blockchain applications with widespread adoption. While the early designs (e.g. Bitcoin) are often the currency of choice by cybercriminals (e.g., in ransomware incidents), they only provide pseudo-anonymity, in the sense that anyone can deanonymize Bitcoin transactions by using information in the blockchain. To strengthen the privacy protection of decentralized payment systems, a number of solutions such as Monero and Zerocash have been proposed. However, completely Decentralized Anonymous Payment (DAP) systems can be criminally exploited, for example in online extortion and money laundering activities. Recognizing the importance of regulation, we present a novel definition of Decentralized Conditional Anonymous Payment (DCAP) and describe the corresponding security requirements. In order to construct a concrete DCAP system, we first design a Condition Anonymous Payment (CAP) scheme (based on our proposed signature of knowledge), whose security can be demonstrated under the defined formal semantic and security models. To demonstrate utility, we compare the performance of our proposal with that of Zerocash under the same parameters and testing environment.

摘要：比特币等分布式支付系统是区块链技术最广泛的应用之一，但早期的分布式支付系统（例如，比特币和以太币）因仅具备假名性质，攻击者可以利用链上公开的交易信息分析出用户的真实身份。为了增强分布式支付系统的隐私保护能力，门罗币和零钞等解决方案被提出来，但这些完全匿名的分布式支付系统易被兰用于在线勒索或洗钱等违法活动。本文提出分布式条件匿名支付系统的定义以及安全需求，以权衡隐私保护和合法监管的关系。通过设计基于知识签名的条件匿名支付方案及其形式化定义和可证明安全，本文设计新的分布式条件匿名支付系统DCAP，并采用与Zerocash相同的参数和测试环境分析DCAP的优势。