Research On Privacy Protection Of Shared Data Based On Blockchai

The blockchain has the characteristics of being safe,reliable,and non-tamperable,and is increasingly being used in education,medical and other scenarios.For example,effective medical data sharing is crucial to the research of new technologies and therapies for treating diseases,improving the ability of human beings to identify public health risks and the level of public medical services.However,the traditional blockchain-based data sharing mechanism enables each blockchain node to have a complete account book,which means that all nodes on the chain can know the data information and identity information.Once used by criminals,It is easy to cause medical privacy data leakage.With the rapid growth of data,how to achieve efficient data sharing under the premise of ensuring data privacy and security on the blockchain has become an urgent problem to be solved.Therefore,this paper studies the privacy protection based on blockchain shared data,and proposes the following two schemes.(1)Aiming at solving the problem of privacy data leakage in the public ledger of the node due to data sharing on the blockchain,a blockchain privacy data management scheme based on zero-knowledge proof is proposed.Under this scheme,a data security sharing mechanism based on smart contracts and a blockchain data privacy protection mechanism based on zeroknowledge proof are designed respectively.Among them,the smart contract-based data security sharing mechanism introduces key homomorphic encryption technology,which can not only ensure that the private data being shared in the public ledger of the node on the chain is hidden,but also ensure that other data information in the public ledger of the node is hidden.All the data in the public ledger of the nodes on the chain can be saved on the blockchain in the form of cipher text,and the automatic and safe sharing of data on the chain can be realized.The blockchain data privacy protection mechanism based on zero-knowledge proof ensures the validity of data sharing behavior and data privacy on the blockchain.Under this mechanism,the dynamic group signature mechanism of anonymity is introduced,which makes the scheme more secure and efficient in terms of computing overhead and communication overhead.Finally,the paper analyzes the performance of the proposed scheme from both asymptotic and practical aspects.The results show that the proposed scheme is efficient and feasible compared with other typical schemes.(2)In the previous chapter,although the designed privacy data management scheme can effectively solve the problem of data privacy protection.However,zero-knowledge proofs can only alleviate but not resolve the contradiction between data availability and privacy protection.Therefore,on the basis of the above research,aiming at solving the problem of how to realize the data availability of consistent supply and demand without revealing any medical privacy data on the blockchain,a blockchain medical privacy data management scheme based on signcryption is proposed.Under this scheme,a signcryption-based medical data storage mechanism and a smart contract-based medical data security sharing and privacy protection mechanism are designed.Among them,the medical data storage mechanism based on signcryption ensures the security of the medical data storage process.Under this mechanism,the introduction of identity-based key publishing technology ensures the security of public and private keys of medical data.Under the smart contract-based medical data security sharing and privacy protection mechanism,the ZK-SNARK-based smart contract is used to meet the requirements of data availability and privacy protection,and the smart contract based on ciphertext policy attribute encryption is used to realize the security sharing of medical data.needs,thus achieving a balance between data availability and privacy protection.At the same time,since this program adopts the consensus mechanism,all medical data sharing processes will be published on the blockchain.Finally,from the analysis of theory and actual performance,the efficiency and feasibility of the scheme are demonstrated.