Research On The Technology Of Data Exchange And Sharing Based On Blockchain

Cloud computing is the development and application of the concepts of distributed computing,parallel computing,and grid computing.In the cloud computing paradigm,cloud service providers can process tens of millions or even billions of information within seconds,and thus providing users with computing and storage resources in the form of services through Internet.However,the mutual distrust between cloud service providers and users makes it difficult to realize data exchange and security sharing.Therefore,users inevitably face some security problems when enjoying these services.In commercial environments.Firstly,cloud service providers need to be paid after completing the task,and the users need to confirm the quality of task completion while making payment.How to solve the trust problem and realize the fair exchange of the computing results and the payment token has become one of the challenges.Secondly,the cloud service provider and the user should sign a service contract when the service agreement is reached.How to exchange the digital signature in the cloud environment is also one of the problems in front of us.In addition,when users exchange and share the data through the storage services provided by untrustworthy cloud,how to ensure the security of data is the last challenge.Blockchain,as an emerging technology in the field of information,is the foundation of constructing value Internet.As we know,blockchain is a technology that consists of distributed data storage technology,point-to-point network communication technology and modern cryptographical technology.It has the characteristics of decentralization,openness,autonomy and tamper-resistant.Therefore,the decentralization of blockchain provides a viable solution for us to build security protocols without the trusted third party.Meanwhile,blockchain is also very suitable for designing data sharing schemes.In this dissertation,we focus on the key issues of data fair exchange and secure sharing based on blockchain.The major research contents includes: how to realize the fair exchange of the computing results and the payment token constructing fair payment,how to realize the fair exchange of digital signature data in the cloud environment,how to realize multiple groups data security sharing in cloud environment.The main contributions are summarized as follows:1.We propose a new fair payment scheme for outsourcing computations based on blockchain,which solve the problem of fair exchange of the computing results and the payment token.Due to the advantages of transaction syntax,we adopt Blockchain-basedcrypto-currency to design the payment protocol.Therefore,the fairness of our protocol can be guaranteed.Moreover,we use commitment-based sampling scheme instead of “ringer” to realize the verification of computing results.Taking the advantages of commitment-based sampling scheme,the proposed protocol is also practical and efficient.2.We propose a fair three-party contract signing protocol based on the primitive of blockchain and solve the problem of fair exchange digital signature.Using the decentralization property of blockchain,our proposed construction allows the participants to exchange signature in a fair way without the involvement of an arbitrator.Besides,we adopt the threshold cryptography and verifiable encrypted signature to guarantee the fairness even when two parties are malicious and collusion.Moreover,the parties only publish the decryption shares to the blockchain.Therefore,the nodes never get the contact and the privacy of the contract content can be preserved on the public chain.At last,3.We propose a data sharing scheme for multiple groups based on consortium blockchain.In our construction,the verification information for auditing is recorded in a tamperresistant database.The database is maintained by all participants by using consortium blockchain technology.Therefore,the auditing process does not require the help of a third-party auditor.We also use the primitive of group signature to achieve anonymous information exchange in the public blockchain.Thus,the privacy of user identities is protected.In our scheme,the manager of the group can trace the actual identity of malicious users.Moreover,the fairness can be guaranteed in the process of solving the dispute,that is,honest users cannot be framed and dishonest users cannot be shielded.