Research And Application Of Privacy Protection Technology Based On Blockchain

Blockchain technology has become a research hotspot in academia and industry due to its traceability and non-tamperability since the technology appeared.With the advent of the blockchain 2.0 era,smart contracts have given the blockchain the possibility to solve more practical application problems.However,due to the open and transparent design of the blockchain technology ledger,the privacy of users has been affected.What is more serious is that the decentralized nature of the blockchain makes it impossible to compensate for privacy leaks like centralized applications.In order to meet the needs of blockchain applications for the protection of user privacy information,in recent years,relevant researchers have analyzed the privacy protection issues of blockchains and proposed corresponding solutions to provide support for the secure implementation of blockchain applications..This thesis aims at the privacy protection problem of the blockchain,combined with the practical application of community governance work,proposed a blockchain privacy protection plan for data transactions and sharing.The main work content,research results and innovations are as follows:(1)Proposed improvements based on Homomorphic encryption algorithm and blockchain privacy protection algorithm for secure multi-party computing.Based on the Paillier algorithm,the decryption process is optimized,and the decryption time of the homomorphic encryption process is reduced.On this basis,combining the two basic issues of the millionaire problem and the safety summation problem in secure multi-party computing,a safety comparison protocol and a safety summing protocol are proposed.Compared with the existing millionaire protocol and improved protocol that solve the millionaire problem,the security comparison protocol has reduced computational complexity.Compared with the existing classic security summation protocol based on secret sharing technology,the security summation protocol has been improved in security.The proposal of these two protocols respectively solves the problem of comparing the size of the data of two blockchain nodes in the ciphertext state and the problem of safe summation of multiple blockchain nodes without revealing their own node data,for the next intelligent The design of the contract provides a theoretical basis.(2)Designed the blockchain privacy protection service transaction smart contract.In the process of community governance,the actual application demand between residents and community service providers-service transactions,has designed a service transaction smart contract that meets the needs of privacy protection.This contract satisfies the verifiability and non-repudiation of general smart contracts,and increases the privacy protection performance that other transaction smart contracts do not have.The smart contract was deployed to the Ethereum blockchain network,which proved its feasibility and correctness.The experimental results show that the contract ensures that both parties to the transaction can complete the transaction without revealing their account information.Multi-resident nodes can Complete consumption statistics without revealing your own consumption data to meet the needs of privacy protection.At the same time,the performance index of transaction throughput is better and more stable than Zcash using zero-knowledge proof.(3)Designed and implemented a privacy protection community governance platform based on two-layer blockchain.This platform mainly completes the two basic tasks of service trading and data file sharing.In order to improve the efficiency of the system,the platform adopts a cross-chain architecture.The task of service trading,which has more interaction,is placed in the service trading alliance chain,and data file sharing is placed in the community governance alliance chain.At the same time,in order to realize the safe sharing of cross-chain data,this thesis proposes a cross-chain data sharing privacy protection scheme.The super nodes designed between the double chains complete the community governance alliance chain staff members' consumption data in the service sale and purchase alliance chain.Controllable acquisition.This platform will complete the main functions of registration and login,service transactions,data file acquisition,data file transmission and downloading,and display each function.