Research On Privacy Protection Of User Identity And Transaction Data In Blockchain Applications

Blockchain,as a point-to-point distributed public ledger technology,has attracted extensive attention in recent years.However,while blockchain technology is decentralized and immutable,nodes in the whole network need to disclose transaction information on the chain in order to achieve consensus,which brings serious privacy problems to users.Therefore,the privacy protection issue in blockchain applications has become the core issue that people have been paying attention to.At present,according to the different application scenarios of the proposed scheme,the blockchain privacy protection can be divided into two types: user identity anonymity and transaction data privacy security.In order to solve these two privacy protection problems,this paper adopts two blockchain privacy protection technologies,that is,zero-knowledge proof protocol and homomorphic encryption technology respectively.In view of the problem of user identity anonymity in current blockchain applications,a privacy security scheme of bidding identity anonymity based on smart contract and zeroknowledge proof is proposed,which was named as BIBZK.The framework replaces traditional databases with blockchain smart contracts that handle business logic.In data interaction,the zero-knowledge proof protocol based on graph isomorphism is used to improve the privacy protection,which not only improves the privacy of information transmission,but also ensures the anonymity and verifiability of participants.Compared to other blockchain-based applications,BIBZK scheme is more secure,efficient and anonymous,ensuring user identity privacy throughout the bidding process.In view of the problem of transaction data privacy disclosure in current blockchain applications,a smart medical data privacy security scheme based on smart contract and homomorphic encryption is proposed,which was named as MDBHE.The framework receives user physiological data collected by wearable devices on the client side and uses blockchain as data storage to ensure that data cannot be tampered with and forged.Secondly,the smart contract is used to write disease prediction model by using fully homomorphic encryption method.The medical data is encoded and encrypted on the client side and uploaded to the cloud platform through the Internet,thus avoiding the privacy disclosure caused by network eavesdropping.In addition,smart contracts are invoked on the blockchain platform for disease prediction.Encrypted user data is used in the prediction model to prevent privacy security problems caused by data leakage on the platform.In MDBHE,an interaction protocol between the client and the cloud is designed to solve the defect that the homomorphic encryption only supports addition and multiplication by the client submitting multiple groups,so as to ensure that the prediction model can carry out complex operations and analyze the performance of the system.Finally,the operation effect of the system is verified through experiments.Without affecting the accuracy of the model,the privacy of transaction data is not disclosed,and the smart medical cloud platform with available and unloanable data is realized.