Blockchain Cross-chain Key Technology Research

After entering the 21st century,with the rapid development of technology,electronic payment has become a commonly used payment method.However,while enjoying the convenience of payment,the security of electronic payment has become more and more important.Since the advent of blockchain technology,this comprehensive technology has attracted widespread attention due to its anti-tampering,distributed,and transparent account characteristics,as well as its practical application in Bitcoin.Blockchain can meet people's requirements for the security of currency transactions.Electronic currency constructed with blockchain is the vane of future currency transactions.In the initial stage of the application of blockchain technology,the project was designed and implemented by different teams according to their needs as various heterogeneous blockchains and different blockchains to serve different institutional systems.Blockchain systems are isolated from each other and not connected.However,as society continues to expand the demand for the diversification and complexity of blockchain applications,there is also a need for message exchange and cross-chain transactions between blockchain systems.When different blockchain systems conduct cross-chain transactions,it is necessary to complete the storage of multiple block ledger information and broadcast consensus to determine whether the current cross-chain transaction information is safe and reliable,and whether it can be chained.The existing cross-chain communication technology faces the processes of heterogeneous network communication between chains,serial transmission,communication information conversion,information consensus,etc.,and there are problems such as long transaction delay,low throughput,and too large transaction subjects.Besides,the security attacks caused by the blockchain system due to its chained ledger structure,such as the double-spending(fork)problem,can cause huge losses to the system.Therefore,efficient cross-chain transactions and resistance to double-spending attacks are the key issues of blockchain cross-chain that need to be solved at this stage.This thesis mainly studies the double-spending solution of the blockchain system,and proposes a double-spending elimination method based on the occupancy mechanism for the block grid system.First,we introduce the definition of double-spending attack problem and existing double-spending solutions,and then this thesis proposes a method of eliminating double-spending based on the occupying mechanism.We introduce a pre-occupied mechanism into the system,and use the asynchronous feature of the block grid system to realize the running process of transaction occupying and waiting to solve the double-spending problem.Through experimental simulation,it is verified that the bifurcation solution based on the occupying mechanism proposed in this thesis can effectively solve the bifurcation problem in the blockchain system.The experiment compared the voting mechanism of the traditional bifurcation solution of the Nano blockchain with the bifurcation solution of the placeholder mechanism,showing that the performance of the placeholder mechanism is better than the traditional voting mechanism under different transaction scales.Since the current blockchain cross-chain method is based on the architecture of Ethereum and Bitcoin,it lacks universality.Therefore,we propose a Java-based cross-chain system framework,which is an independent blockchain system suitable for general cross-chain scenarios.It can provide cross-chain services to two or more blockchain systems with cross-chain requirements.The system's ledger structure and transaction process borrowed from the Nano block grid system,so it has the characteristics of fast transaction speed and high throughput.In the thesis,the Nano block grid structure is first introduced,and then the system structure and process design of the proposed Java-based cross-chain system are introduced.Through the realization of the core module of the cross-chain system---platform transaction module,it specifically includes Java-based refactoring.The Nano block grid system of the structured system starts the block chain,constructs the block,Socket communication,system transaction,account information display,block content display function,and then experimentally verifies the above functions,and the results show that the module has transaction feasibility.Finally,we conducted a security analysis on the constructed Java block grid system.