面向区块链轻节点的支付通道瞭望塔技术研究  

On Watchtower of Payment Channel for Blockchain Light Nodes

作　　者：解岩凯 魏凌波 张驰[1] 王庆涛 孙启彬[1] XIE Yan-Kai;WEI Ling-Bo;ZHANG Chi;WANG Qing-Tao;SUN Qi-Bin(School of Cyber Science and Technology,University of Science and Technology of China,Hefei 230027,China;China Nanhu Academy of Electronics and Information Technology,Jiaxing 341000,China)

机构地区：[1]中国科学技术大学网络空间安全学院,合肥230027 [2]中国电子科技南湖研究院,嘉兴341000

出　　处：《密码学报》2021年第5期778-794,共17页Journal of Cryptologic Research

基　　金：国家自然科学基金(62072426,U19B2023,61871362);安徽省重点研究与开发计划(202104b11020029)。

摘　　要：受限于区块链共识协议,主流加密货币的交易吞吐量远低于传统的金融支付系统.然而,通过修改共识协议提升吞吐量的方案会导致区块链系统安全性、可靠性和去中心化程度的下降,因此这类方案无法得到主流区块链开发者的认同.在不修改区块链共识协议的前提下,支付通道通过链下交易提升了加密货币的交易吞吐量,但支付通道安全性依赖于参与者对区块链的定期监视.故资源受限的移动用户选择将实时监测区块链的任务外包给实时在线的第三方实体,即瞭望塔.瞭望方案设计面临瞭望塔效率、用户链下交易隐私以及用户通道资金安全三个挑战,现有方案通过引入密码技术、可信执行环境技术以及智能合约技术,克服了其中一个或多个挑战.本文对支付通道网络中各类瞭望塔方案进行了分析,基于方案的应用背景将其分为比特币中的瞭望塔和以太坊中的瞭望塔两大类,并评述了每个方案的原理、优势与不足.最后,针对目前方案未解决的问题,提出了可行的瞭望塔系统的未来技术路线.Restricted by the consensus protocol,the transaction throughput of mainstream cryptocurrencies is much lower than traditional financial payment systems.By modifying consensus protocol,some schemes increase the throughput of cryptocurrencies,however,those schemes would make the blockchain tend to be centralized,which violates the objective of blockchains.Thus,this approach cannot be recognized by cryptocurrency developers.Without modifying consensus protocol,payment channel enables cryptocurrency to be scalable by performing transactions off-chain without increasing the load of the blockchain.However,the participants need to monitor the blockchain at regular intervals to ensure payment channel security.Therefore,the resource-constrained mobile user offloads such monitoring task to a real-time active third party named watchtower.The development of watchtower confronts three challenges,namely efficiency,privacy of the off-chain transaction,and the security of channel funds.Existing such schemes utilize cryptography,the trusted execution environment,or the smart contract to solve one or more challenges.This paper classifies the existing schemes into two categories based on the application scenarios:Bitcoin blockchain watchtower and Ethereum blockchain watchtower,and analyzes the principle,advantages,and disadvantages of each scheme.Finally,a feasible roadmap for unresolved problems of the current watchtower schemes is proposed.

关 键 词：区块链 加密货币 支付通道 瞭望塔 闪电网络 

分 类 号：TP309.7[自动化与计算机技术—计算机系统结构]