【作者】 戴炳荣；

【导师】 姜胜明；

【作者基本信息】 上海海事大学 ， 信息管理与信息系统， 2021， 博士

【摘要】 当前,以信息技术为主导的变革对社会和经济产生了巨大的影响。区块链是新一代信息技术的革新力量,是我国核心技术自主创新的重要突破口,作为数字经济重点产业之一,已被列入国民经济十四五规划纲要。区块链在对等网络环境下通过透明和可信规则构建不可伪造、不可篡改和可追溯的新型数据系统结构,是新型分布式商业的基础,其应用已经从最初的数字货币扩展到供应链管理、金融保险、数字版权、教育、物联网、智能制造等社会的各个领域。随着区块链技术和经济的发展,区块链之间的数据交互、应用协同需求日益增加。在企业级的联盟链场景下,跨链技术承担的不仅仅是数据的转移,更多是打通不同区块链网络背后的协作网络和跨机构业务流程,提高在不同区块链上相互关联企业之间的协作效率。受制于数据结构、接口协议、共识机制乃至于业务模式等的不同,各个区块链应用间形成了新的“链孤岛”,限制了区块链之间的资产交换、业务协同等互操作。本文在充分分析区块链技术特点和区块链互联网发展需求的基础上,研究跨链交互架构、跨链资产交换机制、跨链用户统一标识等技术,并在实现的跨链系统原型上进行了实验和验证。主要研究工作和创新点包括以下几个方面:(1)研究跨区块链系统的交互架构,提出一套多级多链的区块链互操作架构。从区块链的数据层、网络层、共识层、合约层和应用层五层架构模型入手,研究了跨链互操作的分层结构,深入分析了跨链互操作中的跨链通信机制、跨链共识机制和跨链智能合约等关键技术的实现机制。同时分析了单链扩展、多链跨链到多级多链跨链的发展阶段。提出了一套多级多链的区块链跨链架构模型以及支持多级多链跨链的交互协议栈,研究了跨链组件模型以及跨链适配器、跨链网关、跨链注册中心、中继链等核心组件的功能,实现跨链消息的封装、传输、互操作控制等。(2)研究基于公证人及哈希锁定的多跳资产交换方法,提出一套公证人的评价机制以及多跳跨链资产交换方法。针对跨链公证人机制的节点信用监督不足问题,通过将用户评价和节点本身信息进行综合分析和互相验证,设计了公证人节点信任评价模型和基于改进Page Rank算法的节点评价算法。在此基础上,提出了一种新型的支持跨区块链多跳资产交换模型,通过公证人多签名算法提高传统哈希锁定机制的安全性。设计了多跳交易环路检测方法、多方密钥协商算法,将该密钥作为多重签名、资产解锁的条件,实现了多跳跨链资产交换功能。基于以上方法设计了密钥协商、资产锁定、资产解锁三阶段式的跨链交易流程,通过公证人与多重签名的融合方法解决公证人、用户等签字合谋的问题,提升了跨链资产交易的可信度。(3)研究面向跨链交互的用户标识及合约执行技术,提出了跨链智能合约的执行方法以及跨链用户的分布式统一标识机制。结合跨链资产交换及跨链数据交互需求,通过设计跨链读、跨链写的基本操作原语,提出了一套跨链智能合约执行的协调机制,将跨链合约执行定义为二阶段和四阶段两种协议,跨链系统与参与链之间通过区块头同步合约来进行跨链交易和事务验证,保障跨链信息真实可信。同时,结合跨链的实现需要,提出了一套面向多源异构区块链的分布式统一身份标识方案,通过关系映射实现同一用户在不同区块链系统中身份的关联,并引入零知识证明协议和数字签名实现用户的跨链访问功能以及保障用户在跨链系统身份隐私。更多还原

【Abstract】 Nowadays,changes led by information technology have had a huge impact on society and the economy.Blockchain is the innovation force of a new generation of information technology and an important breakthrough for the independent innovation of China’s core technology.As one of the key industries of the digital economy,it has also been included in the outline of the14 th Five-Year Plan for the National Economy.Blockchain constructs a new data structure that is unforgeable,unchangeable,and traceable through transparent and trusted rules in peer-topeer network environment,which is the foundation of a new distributed business.Its application has expanded from digital currency to supply chain management,financial insurance,digital copyright,education,Internet of things,intelligent manufacturing,and other social fields.With the development of blockchain technology and economy,the demand for data interaction and application collaboration between blockchain is increasingly emerging.In the context of enterprise level alliance chain,cross-blockchain technology is not only responsible for the transfer of data,but also to get through the cooperation network and cross organization business process behind different blockchain networks,so as to improve the cooperation efficiency among enterprises related to different blockchains.Restricted by the differences in data structure,interface protocol,consensus mechanism,and even business model,a new "chain islands" have been formed between blockchain applications,which directly limit the interoperability of asset exchange and business collaboration between blockchains.Based on the full analysis of the technical characteristics of blockchain and the development needs of blockchain Internet,this paper will study the cross-blockchain interaction architecture,crossblockchain asset exchange mechanism,cross-blockchain user unified identification,etc.,and carry out experiments and verification on the prototype of the cross-blockchain system.The main contributions of this thesis are summarized below.(1)Research on interaction architecture of cross-blockchain system,and propose a multilevel and multi-chain blockchain interoperability architecture.Starting from the five-layer architecture model of blockchain,including data layer,network layer,consensus layer,contract layer,and application layer,this paper studies and analyzes the hierarchical structure of cross chain interoperability,and deeply analyzes the implementation mechanism of cross-blockchain communication mechanism,consensus mechanism and smart contract collaboration mechanism.Meanwhile,the development stages of single-chain expansion,multi-chain crossblockchain and multi-level multi-chain cross-blockchain are analyzed.This paper proposes a multi-level and multi-chain blockchain interoperability architecture,studies the cross-blockchain component model and the functions of cross-blockchain adapter,gateway,registry and relay chain,and deeply analyzes the interaction protocol stack of cross-blockchain,so as to realize the encapsulation,transmission and interoperability control of cross-blockchain messages.(2)Research on multi-hop asset exchange based on notary and hash-lock,and propose a notary evaluation mechanism and multi-hop cross-blockchain asset exchange method.Aiming at the problem of insufficient node credit supervision of the cross-chain notary mechanism,through comprehensive analysis and mutual verification of user evaluation and node information,a notary node trust evaluation model and an improved Page Rank based node evaluation algorithm are designed.On this basis,a new model of multi-hop asset exchange supporting cross-blockchain is proposed.The security of traditional hash-locking mechanism is improved by notary multi-signature algorithm.The detection method of multi-hop transaction loop and multi-key negotiation algorithm are designed,and the key is used as the condition of multisignature locking and unlocking,thus the multi-hop cross-blockchain asset exchange capability is realized.Based on the above methods,a three-stage cross-blockchain transaction process of key agreement,asset locking and asset unlocking is designed.The combination of notary and multi-signature solves the problem of signature collusion between notary and user,and improves the credibility of cross-blockchain asset transactions.(3)Research on user identification and contract execution key technologies for crossblockchain interaction,and propose the execution method of cross-blockchain smart contract and the distributed unified identification mechanism of cross-blockchain users.Combined with the requirements of cross-blockchain asset exchange and data interaction,by designing the basic operation primitives,a coordination mechanism cross-blockchain smart contracts is proposed,and the cross-blockchain contract execution is defined as two-stage and four-stage protocols.The cross-blockchain transaction and transaction verification are carried out by the block head synchronization contract between the cross-blockchain system and the participating chain,so as to ensure the authenticity and reliability of the cross-blockchain information.Meanwhile,combined with the needs of cross-blockchain,a distributed unified identity scheme for multi-source heterogeneous blockchain is proposed.The identity association of the same user in different blockchain systems is realized by relational mapping,and Zero-knowledge proof protocol and digital signature are introduced to realize user’s cross-blockchain access function and protect user’s identity privacy in cross-blockchain system.更多还原