Research On Data Access Control And Sharing Scheme Based On Consortium Blockchain

Data sharing is a powerful way to solve the problem of "data island" and tap the potential value of data.The premise of realizing full data sharing is to ensure the data security and credibility.The traditional way of data storage often adopts centralized architecture,which is prone to trust and security problems.Blockchain is a decentralized,tamper proof,traceable and multi-party distributed database,provides a reliable solution for data security sharing.However,with the passage of time,the storage space required by blockchain system will be larger and larger,so storage optimization is an important challenge for blockchain technology.On the other-hand,the centralized storage architecture leads to the data producers have no control over the data.For instance,large websites not only collect personal information such as users' hobbies and browsing habits,but also collect personal privacy data,which brings potential threats to personal privacy security.Therefore,it is necessary to strengthen the data owner's control over the data and decide whether other users have the right to access the data.In order to solve the above problems,the following three aspects of research work have been carried out:(1)A fine-grained access control mechanism based on symmetric encryption algorithm and attribute-based encryption algorithm is proposed.This mechanism encrypts the data with symmetric encryption algorithm,and then encrypts the key of symmetric encryption algorithm with attribute-based encryption algorithm.Different access policies are set to realize the fine-grained access control of data owner and protect the privacy of data owner.The experimental results show that this mechanism has better time efficiency than the access control mechanism only using attribute-based encryption algorithm in the case of storing small files.(2)This paper presents a decentralized "off chain" storage scheme based on inter planetary file system(IPFS).This scheme stores the encrypted data on the IPFS network,and stores the content hash value generated by IPFS on the blockchain,which is convenient for data consumers to access the encrypted data,alleviates the storage pressure of the blockchain,and effectively improves the scalability of the blockchain.(3)A data access control and sharing scheme based on consortium blockchain is proposed.The scheme stores the hash value of data,location information of data ciphertext and access control strategy on the blockchain to ensure the safe sharing of data,provide fine-grained access to data,and enhance the scalability of blockchain system storage.Based on this scheme,a prototype system based on Hyperledger Fabric consortium blockchain is developed by using smart contract technology.