The Research On Third Party Auditing Schemes For Data Update And Recoverable In Cloud Storage

With the rapid development of cloud computing,cloud storage is used by more people because of its benefits: relief of user's storage pressure and management burden,universal data access with location independence,and avoidance of capital expenditure on hardware,software and personal maintenance.Although cloud storage has a lot of advantages,people are more concerned about their security problems.Once the users outsource the data to the cloud,they lost the physical control of their files.Because cloud servers suffered from many threats such as hardware failures and external attacks,the outsourced data is at risk of being tampered or deleted,therefore,verifying data integrity is essential.In order to ensure the integrity,the cryptographers proposed auditing schemes to help users audit their data rely on a trusted public third party auditor(TPA),users can verify the data integrity with the help of TPA,which reduces the burden of users.Design a secure and efficient third-party audit scheme is an important research issue to improve the quality of cloud services,in practice,users often required to update their remote data;for each important document,it is not enough to execute the auditing tasks,while the data is detected corruption.In this case,users want to recover the original document.So,our purpose is to design third-party auditing schemes that support data update and recovery.According to the purpose of this thesis,we study a large number of third-party audit schemes,then we demonstrate that the PPASGD scheme proposed by Wang et al.can not resist the replace attack and data tampering attack,the SDIVIP scheme proposed by Yu et al.can not resist data tampering attack and has the danger of revealing data privacy.We give our improvements to overcome these security weaknesses,and demonstrate the security of our improved solution.In order to let the users update the cloud data,we propose a third-party auditing scheme which support data update.To improve the audit efficiency,the scheme provides users to dynamically update data and can protects users' data privacy.Then,we give the detailed proof of security and conduct a performance analysis through experiments.Under the same security parameters,our proposed first scheme reduces the average communication cost 50% and reduces the average computation cost 7% compared with other similar audit schemes.On the other hand,in order to recover the corrupted data in cloud server,we propose a third-party audit scheme which support data recovery.By using regenerating code,the scheme can reduces the repair bandwidth when restore the original data file,the scheme also provides privacyprotection.Similarly,we also give the detailed proof of security and conduct a performance analysis through experiments.Under the same security parameters,our proposed second scheme reduces the average computation cost 10% compared with other similar audit schemes.