Research On Integrity Auditing For Data In Cloud With User Revocation

Cloud storage——an important branch of cloud computing,is a new technology in network storage.Through the cloud storage technology and the shared services provided by the cloud,people can share their data as a group to other users.More specifically,every user in the group can not only acquire and modify data shared by other users,but also share the latest updated version of data to users in the group.However,in the process of data uploading,the data may be intercepted by eavesdroppers because of the transparence of wireless channel transmission;in addition,in the re-signature process,how to avoid the collusion attack between the cloud and revoked users without affecting integrity audit has also become an important research topic.In order to solve these security problems,the works of this article are as follows: 1.The integrity audit based on a threshold hybrid encryption scheme without trusted center.Because of the transparence of wireless channel,data in plaintext form are easily intercepted by eavesdroppers during being uploaded.What's more,the single-manager mode can easily result in the so-called ‘authority deception' because the manager has too much authority.In order to avoid the drawbacks of the above models,our scheme proposes a threshold hybrid encryption which can improve efficiency of encryption and security of system.At the time of decryption,managers have to cooperate so that it can distribute the authority of each manager and improve the robustness of system.2.The integrity audit based on the backup data.In a user group,once a user is revoked,the data signed by the revoked user should be signed by other users.However,there is a collusion attack between the cloud and revoked users in many papers during the stage of data resigning.This scheme uses the backup data to recover data singed by revoked user directly.When a user is revoked,the cloud can delete all data of the revoked user,and then let any legitimate user sign the backup data in order to replace the deleted data.The process can effectively resist the collusion attack between the cloud and the revoked users.This scheme can improve the efficiency of the system,at the same time also improve the security of the system.