Research On Cloud Storage Integrity Audit Mechanism Based On Alliance Chain

With the advent of the data era,the advantages of convenient and efficient cloud storage have become more apparent.However,cloud storage separates the ownership of data from the right to use,so that cloud storage users cannot ensure the integrity of cloud data.The so-called data integrity refers to the characteristics that the cloud data and the local data before migration are consistent.Faced with the problem of cloud storage integrity,auditing cloud data is not only to protect user data security,but also to authenticate cloud reputation.Therefore,it becomes particularly important for the research of credible cloud storage integrity audit.In recent years,researchers at home and abroad have made many achievements in cloud storage integrity audits,but there are still two deficiencies.On the one hand,in the cloud storage integrity audit that supports dynamic operations,the Merkle tree used in the dynamic audit data structure has become a bottleneck to further improve audit efficiency,and there are hidden security risks in the audit process.On the other hand,most of the current cloud storage integrity audits use third-party audits.Since thirdparty auditors are not absolutely credible,cloud storage users face the risk of being deceived by collusion,that is,the audit results are not reliable and fair.Faced with the above two deficiencies,the thesis reconstructs the Merkle tree of dynamic audit data structure and builds a reliable audit alliance based on the highly trusted alliance blockchain architecture.The research content includes three levels,namely cloud storage integrity audit method,consensus algorithm and audit model.They are Multi-copy Dynamic Cloud Storage Auditing Method Based on IMB Tree(MCAM),CAPBFT Consensus Algorithm Based on Cloud Storage Audit Alliance(CAPBFT)and Cloud Storage Integrity Auditing Model Based on Consortium Blockchains(CSACB),as follows:(1)The Multi-copy Dynamic Cloud Storage Auditing Method Based on IMB Tree is proposed to provide safe and efficient audit calculation for the audit model.Firstly,construct an efficient IMB tree suitable for dynamic data,and use it as the dynamic audit data structure.Secondly,the masking rate is introduced to control the masking extent of the duplicate data blocks,and then the similar characteristics of the adjacent copies are used to reduce the amount of data transferred for migration.Finally,the logical characteristics and physical content of the data block are aggregated to generate challenge evidence,and unified verification in bilinear mapping that avoids the transmission of the logical evidence of the data block and the related hash calculation.Theoretical analysis and experiments show that this method has advantages in safety and performance.(2)The CAPBFT Consensus Algorithm Based on Cloud Storage Audit Alliance is proposed to provide a highly credible,highly secure,and efficient consensus capability for the audit model.For the cloud storage audit alliance scenario,CAPBFT gives consensus nodes different organization identities on the basis of PBFT,and provides an identity basis for tripartite consensus.Then,from two angles of the cloud storage user and cloud service provider,the consensus process is divided into two stages of consensus,namely the alliance request consensus and the alliance audit consensus,to ensure the auditability of the request and the fairness of the audit results.Secondly,client ordering mechanism and organization threshold signature mechanism is introduced,which can not only reduce the communication and calculation pressure of a single node,but also enhance the trust of various organizations in the consensus results.Theoretical analysis and experiment show that in the scenario of cloud storage audit alliance,CAPBFT has a certain improvement in security and performance compared to PBFT consensus algorithm.(3)The Cloud Storage Integrity Auditing Model Based on Consortium Blockchains is proposed.Firstly,the layer certificate chain is used to perform dual identity management for alliance chain members.Secondly,it is based on the CAPBFT consensus mechanism to ensure the consistency of consensus results.The dual-chain,basic audit chain and meta-information chain,are adopted to support cloud storage dynamic integrity audit.Then,a reputation mechanism is introduced to evaluate the results of request review and integrity audit.Audit smart contract based on the reputation mechanism and MCAM is constructed to ensure the reliability of the audit process.In addition,a data block label index mechanism is established to assist the audit contracts in operating efficiently.