Research On Blockchain Data Privacy Access Control And Sharing Mechanism

Blockchain adopts asymmetric encryption,distributed computing,hash pointer,Merkle tree,digital signature and other technologies.Due to its open and transparent,autonomous,tamper-proof,decentralized and traceable characteristics,it is widely used in various industries.The security problems are also frequent,seriously affecting the application of blockchain.Data on the traditional blockchain is open to the whole network nodes,and the update operation of data records is also transparent,which will accompany the occurrence of user information leakage.Although blockchain itself has the characteristics of anonymity and privacy,with the development of blockchain,it has been unable to meet the needs of users.How to effectively protect the data privacy and user privacy on the blockchain and ensure the security of data integrity,transmission efficiency,storage efficiency and application is very important to break the bottleneck of the blockchain technology development and promote the application.The main research work of this thesis is as follows:Firstly,starting from the basic structure of blockchain,this thesis analyzes the privacy issues at all levels of blockchain,and analyzes the advantages and disadvantages of the existing blockchain privacy protection scheme,the disadvantages and advantages of the data privacy access control scheme based on blockchain,and the application and development of the data sharing scheme based on blockchain.Secondly,in terms of the transaction privacy and identity privacy problems existing in the blockchain privacy protection scheme,the transaction on the blockchain,searchable public key encryption and attribute encryption are combined to construct the blockchain transaction privacy protection access control scheme based on searchable attribute encryption.The access control of data users on blockchain is realized by introducing attribute encryption based on ciphertext policy.Searchable encryption is introduced to encrypt the plaintext and keywords of the transaction information,and the ciphertext and keywords of the transaction information are stored on the blockchain,which solves a series of problems such as non-tampering and supervision of transaction privacy.Then we present the scheme model and prove the security of the scheme based on the random model and the bilinear problem.Finally,in view of the privacy leakage risk and data sharing of blockchain data,this thesis proposes a blockchain data sharing privacy protection scheme based on inverted index of searchable symmetric encryption and proxy re-encryption.The scheme uses the proxy re-encryption technology to encrypt the data and store it to the external database.Only the user with the corresponding proxy re-encryption key can view the detailed information of the data,which protects the data privacy.In order to further improve the query efficiency of data on the blockchain,the inverted index structure with high query efficiency is used,the query is executed by executing the binary search algorithm.