一种支持高并发的多人链下支付方案  

A High-Concurrency Multi-Party Off-Chain Payment Scheme

作　　者：葛钟慧 张奕 龙宇[2] 刘振 刘志强[2] 谷大武[1,2] GE Zhong-Hui;ZHANG Yi;LONG Yu;LIU Zhen;Liu Zhi-Qiang;GU Da-Wu(School of Cyber Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240;Department of Computer Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240;Shanghai Viewsource Information Science&Technology Co.,Ltd,Shanghai 200241)

机构地区：[1]上海交通大学网络空间安全学院,上海200240 [2]上海交通大学计算机科学与工程系,上海200240 [3]上海观源信息科技有限公司,上海200241

出　　处：《计算机学报》2021年第1期132-146,共15页Chinese Journal of Computers

基　　金：国家自然科学基金(61672347,61672339,61872142,61932014,61572318);“十三五”国家密码发展基金(MMJJ20170111);上海市2019年度“科技创新行动计划”(19511101403,19511103900);上海市闵行区中小企业技术创新计划(2018MII110)资助~~

摘　　要：随着区块链技术研究与应用的快速发展,可扩展性瓶颈对于其在大规模应用场景下的主要制约作用逐渐凸显.作为解决区块链可扩展性问题的关键技术之一,支付通道技术将交易清算从链上的全网矿工认证转移到链下通道内的支付双方认证,从而实现了支付近乎即时确认;结合路由算法构成的支付通道网络,实现了任意两点间的链下支付,极大地提升了区块链的可扩展性.然而,目前的研究大多针对双人通道,涉及到多方的链下支付无法在单个通道内或通过单条支付路径完成,同时对于具有频繁、相互交易需求的多个人,两两间建立通道或通过路由来完成链下支付的所需链上开销与复杂性较高.现有的多人通道方案效率低下,不适用于高并发的链下支付场景,且不能支持跨通道支付,限制了链下支付的范围.基于此,本文在原有多人通道框架内改进了通道内状态更新机制,将通道状态依据支付串行更新变为并行更新,并引入支付有效期来减轻网络时延与高并发支付场景对支付有效性的影响,从而实现通道内支付处理效率的提升和对链下高并发支付场景的支持,此外在不关闭通道的前提下允许节点退出通道以提高通道可持续性;将多人链下支付从通道内推广至跨通道,具体地,在多人通道内引入条件支付与赎回支付,以支持安全的跨通道支付,同时将原双人通道网络中的基于图嵌入的贪心路由算法应用至多人通道网络中,以实现网络任意两点间的支付路径寻找.分析表明,多人通道网络具备可行性,并可实现安全的链下支付;我们对链下支付的路由情况进行模拟,实验结果显示,该方案实现了88%的链下支付成功率为88%,且在静态场景下的路由开销相对双人通道网络降低了28%,面对网络环境与设置变化路由性能更加稳定.由此,此方案具有高效、支持高并发、稳定的特性,满足实际应�Blockchain has received great attention in recent years.Due to its inherent attribute of decentralization,the low throughput impedes its large-scale applications.As one of the most promising solutions to the scalability issue,Payment Channel Networks(PCNs)move the on-chain payments into off-chain payment channels,taking the underlying blockchain as the arbitration platform.While an on-chain payment needs to be verified by all mines in the blockchain network,an off-chain payment needs only to be approved by both parties within the channel,leading to nearly instant payment confirmation.In combination with routing algorithms,counterparties without a direct payment channel can accomplish payments in the network via a path of intermediaries,which broadens the scope of off-chain payments.However,current researches mainly focus on two-party payment channels,payments with multiple payers or payees cannot be accomplished within one channel or via a single payment path.At the same time,for a group of people who make payments mutually and frequently,launching off-chain payments either by establishing two-party channels between each pair or through intermediaries leads to high on-chain cost and payment complexity.As for Gnocchi,the current multi-party off-chain payment scheme,there is a lack of efficiency and fails to support high-concurrency in-channel payments.Besides,there is no support for cross-channel payments,which limits the range of off-chain payments.In this paper,we improved the operation mechanism of Gnocchi to achieve the enhancement of in-channel payment processing efficiency and the support of high-concurrency off-chain payments.Similarly,we continued the introduction of supervisor within the multi-party channel as the proposer of updating channel state in each round.Differently,we transferred the serial channel state update into the parallel update and regard payments the supervisor receives in a certain time period as in one round.To reduce the impact of network latency and high-concurrency payment scenarios

关 键 词：区块链 多人通道 链下支付 高并发 路由 

分 类 号：TP309[自动化与计算机技术—计算机系统结构]