Research On Data Privacy Protection Technology Of Blockchain Based On Secret Sharing

As a frontier technology in the field of security,blockchain has attracted wide attention as soon as it is proposed.With the rapid development and widespread application in recent years,the problems of privacy leakage and data security are becoming more and more prominent.Compared with the traditional centralized service architecture,blockchain does not rely on a specific central node,and its decentralized feature can effectively avoid the single point of collapse and illegal embezzlement of centralized servers.But in the public chain platform,in order to ensure that the distributed nodes quickly reach a unified consensus,all transaction records on the chain must be open,and any node can access the data at any time,which significantly increases the risk of user privacy leakage.Therefore,in order to ensure the privacy of open data on the chain and effectively promote the construction of network security in the information age,how to use safe and efficient technical means to ensure the privacy of sensitive data on the blockchain has become a research hotspot in the academic community.As a common means of privacy protection,encryption mechanism can be widely used in many scenarios.However,due to the open environment of blockchain and different performance of nodes,it does not have strong computing power,so the traditional encryption scheme is difficult to meet the needs of verifiable computing.Therefore,many researchers have carried out research and Analysis on encryption algorithms with homomorphism.Compared with other privacy protection schemes,secret sharing algorithm with homomorphism can effectively solve the problem of cooperation between untrusted groups,which makes its combination with blockchain have natural advantages.But at the same time,multi-party participation will inevitably lead to the fairness of the scheme,and multi round communication will inevitably reduce the efficiency of the blockchain.Therefore,it is of great significance to study a fair and verifiable data sharing encryption scheme that supports homomorphic computing to satisfy the trusted computing of blockchain.In addition,with the acceleration of the process of medical digitization,the privacy and security of medical data in the process of sharing is also widely concerned.With its safe and reliable decentralized characteristics,blockchain is gradually applied in the field of health care.Considering the verifiable computing requirements in the medical insurance settlement scenario and the problems in the reimbursement process,such as the difficulty and slow speed of insurance claims,this paper studies and designs a medical insurance data settlement model that can support the collaborative work of different levels of participants,which has important practical application value for protecting the data privacy of patients and promoting the development of medical and health undertakings in China.Based on secret sharing algorithm and from the perspective of blockchain privacy protection,this is studies data encryption sharing and medical insurance information settlement,including the following contents:(1)Firstly,we review the blockchain foundation,cryptography knowledge and model checking theory related to our research,including blockchain architecture,classification and technical features,secret sharing,homomorphic computing and zero knowledge proof in cryptography,and formal modeling and verification in model checking.At the same time,it also introduces the related cryptographic algorithms and security analysis methods,including provable security theory and model checking tool UPPAAL based on timed automata.(2)Secondly,traditional encryption schemes are not suitable for blockchain environment,and have the problems of centralization and low verification efficiency.Based on homomorphic secret sharing algorithm,a fair verifiable data sharing encryption scheme based on blockchain is proposed.By combining the outsourcing strategy and zero knowledge proof,the scheme effectively reduces the computing burden of the blockchain,and realizes the efficient verification homomorphic calculation of the ciphertext data on the chain.At the same time,it adopts the distributed key agreement,so that the calculation fairness can be effectively guaranteed,and the security goal of decentralization can be achieved.Then,the formal definition and security model of the scheme are given,and under the random oracle model,it is proved that the proposed scheme can meet the expected security properties.Compared with the existing similar schemes,the results show that the proposed scheme can not only effectively protect the privacy of data and the fairness of users,but also has certain advantages in the efficiency of verification.It can meet the needs of efficient collaboration among untrusted groups on the blockchain.(3)Finally,aiming at the verifiable computing requirements in the application scenario of blockchain and the situation that each participant has different levels and properties,a grading medical insurance data settlement model based on blockchain is designed by combining the fair verifiable data sharing encryption scheme and medical insurance reconciliation scenario proposed in(2).Thanks to the verifiable homomorphic computing characteristics of the encryption scheme,the proposed model can provide fine-grained,safe,reliable and efficient verifiable medical insurance expense settlement function for different levels of medical institutions and different types of insurance institutions.Then,combined with the model checking theory,the system model is established by timed automata,and the security properties are described by temporal logic.Finally,the model checking tool UPPAAL is used to formally verify the model.The results show that the model can not only meet the expected function and security objectives,but also meet the requirements of correctness,availability and robustness in system logic and interaction process.