Research On Privacy-preserving Audit Mechanism For Cloud Storage

Cloud storage service brings many convenience to user data storage.To save local storage overhead,users store data to the cloud server and delete local copies.Data outsourcing storage to cloud server is convenient for users,but also faces many security risks.The cloud server will lose the data stored by the user due to the hardware and software failure.In order to save storage space,the data that users do not often access is intentionally deleted.Therefore,the data integrity stored in the cloud server is challenged severely.As an important technology to detect data integrity,cloud storage data integrity audit protocol has been widely concerned.This thesis focuses on the data integrity audit of privacy protection in cloud storage,and proposes a secure remote data integrity audit scheme to protect privacy.Due to the huge amount of data stored in the cloud and the limited resources of users,it is almost impossible for users to detect the integrity of data by themselves.In order to solve the problem of limited user resources,users will entrust a professional third party auditor(TPA)to complete the data integrity test instead of themselves.However,the third-party auditor is not completely credible.In the process of data integrity audit,the third-party auditor will be curious about the data information stored by users,when the protocol of data integrity challenge response with cloud server is implemented,the third party auditor will analyze the user's data information from the data integrity proof sent by the cloud server.And the identity of the users who upload data will be exposed to the cloud server because of the audit tag.Based on the unconditional anonymity of ring signature,this thesis proposes an integrity audit scheme to protect the identity privacy and data privacy of users who upload data.In some scenarios,users need to share data with other users through cloud storage services.In this case,in addition to protecting the identity of users who upload data,cloud storage services should also need to increase incentive mechanisms to stimulate users to share data and punishment mechanisms to track down malicious uploaders.This thesis proposes a data integrity audit scheme that supports incentive and punishment to protect the identity privacy of data uploaders.The scheme combines provable data ownership(provable data)Possession(PDP)and conditional anonymous ring signature which can not only protect the identity privacy of the uploader,but also reward the real data uploader and punish the malicious uploader without the need of a trusted third party.