Research On A Secure Cloud Storage Scheme With Access Control Baed On Blockchain

With the rapid development of cloud computing,a growing number of companies and individuals are choosing to outsource data to cloud services.To protect the security and privacy of data,the data typically needs to be encrypted before it is stored to the cloud server.In cloud storage systems,secure access control of data is an important research field.Attribute-based access control can effectively ensure the security of data information.Since the data on the cloud server is stored in the form of ciphertext,the retrieval of these encrypted data is also a challenge.While ensuring information security,the attribute-based searchable encryption scheme not only achieves keyword retrieval of ciphertext,but also implements fine-grained access control.However,in traditional access control schemes and searchable encryption schemes,keys are distributed by trusted third parties,the center authority.If these third-party organizations are dishonest or attacked,the security of the entire system will be threatened.This dissertation focuses on the decentralization of secure cloud storage scheme based on blockchain.The main work is as follows:1)Aiming at the problem of center authority in the existing attribute-based encryption access control scheme,a secure cloud storage access control framework blockchain-based is proposed.Based on the existing ciphertext policy attribute-based encryption algorithm,this framework introduce the Ethereum blockchain technology,which solves the problem of single point failure of center authority in traditional schemes to a certain extent,and achieves the decentralization of cloud storage access control schemes.The data owner,in this scheme,can assign an access validity period to the data user while assigning a property set to the user.The data user can correctly execute the data decryption algorithm if and only if it is within the valid access period and the data user’s attributes satisfy the access control policy.At the same time,the introduction of the blockchain is equivalent to adding a log system to the access control scheme,and all access operation records have the advantages of being non-tamperable and non-repudiation.2)For the existing searchable encryption scheme,the center authority may have a single point of failure problem,a keyword searchable encryption scheme based on blockchain is constructed.Based on the existing attribute-based searchable encryption scheme,by introducing the Ethereum blockchain technology,the decentralization of the cloud storage searchable encryption scheme is realized.The data owner and the data user interact through the smart contract so that each search and access record of the user can be saved in the blockchain network.Therefore,the cloud server forges false search results can be prevented,and the integrity verification function for the search results is realized.Finally,the security analysis and experimental results show that the scheme has more advantages than the original scheme.