Research And Implementation Of Blockchain Data Sharing System Based On Attribute-based Encryption

With the rapid development of Internet information technology,cloud storage services are more and more widely used.However,cloud storage services as a non-completely trusted third party,which save unencrypted user data to the cloud will seriously threaten the absolute control and privacy of user data.Therefore,the data encryption and access control mechanism of attribute-based encryption algorithm has attracted the attention of researchers.However,the attribute-based encryption algorithm has the problem of privacy security that cannot protect user attributes in the encryption policy and the single point of failure problem of the attribute authorization center,which become obstacles to its application in cloud storage services.This paper researches the attribute-based encryption algorithm and the blockchain data sharing system,aiming to improve the privacy security and high availability of the attribute-based encryption algorithm,and solve the problem of secure storage of user data in the blockchain data sharing system,which is of great research significance to improve the privacy security and data storage security of users in cloud storage services.Aiming at the problem that the access structure in the attribute-based encryption algorithm cannot protect user attributes and the single point of failure of the attribute authorization center,this paper proposes an attribute-based encryption scheme SPABE that supports policy protection.In this scheme,the protection of user attributes in the encryption policy is realized by obfuscating the user attributes by converting the encryption policy into a multivariate polynomial.Meanwhile,the SPABE scheme adopts the idea of one master and multiple slaves locally and distributed election globally to improve the high availability of the attribute authorization center and solve the single point of failure problem of the attribute authorization center.The security of SPABE scheme is verified by security analysis.The performance analysis and experimental comparison results show that this scheme reduces the storage overhead of ciphertext,and reduces the computational complexity in the encryption and decryption stages.Therefore,the SPABE scheme not only improves the security and high availability,but also improves the computational efficiency in the encryption and decryption stages.Aiming at the problems of user data control,user privacy security and data storage security in current cloud storage services,this paper designs and implements the blockchain data sharing system BCDS.In this system,the SPABE scheme is used to directly encrypt user data to prevent the system from directly contacting user data,to ensure absolute control and privacy of user data,and through the access control mechanism of the SPABE scheme,the secure sharing of data between users is realized.In the meantime,the Ethereum smart contract for users and files is designed in the system to replace the traditional database,and the traceability of the blockchain is used to protect the files uploaded by users.Combined with the IPFS distributed storage system to store user-encrypted files,it ensures the safe storage of user data and solves the problem of file damage caused by force majeure factors.