Research On Secure Deduplication Method Of Encrypted Data In Cloud Storage Environment

With the rapid development of information technology,the amount of data increases exponentially.Since the gradual shortage of local storage resources,many users have to migrate their data to a remote cloud server.Because of this,the same data may be stored into cloud server multiple times by many different users,hence massive storage redundancy gradually formed,which causes a huge storage burden for cloud server.Deduplication therefore receives great attention from both academic and industrial societies.Plaintext data deduplication is a simple problem,but users tend to encrypt their data with their own keys before uploading them to the cloud,which makes it difficult to perform deduplication.Under the premise of ensuring security,it is hard to realize the encrypted data deduplication.Therefore,how to design secure encrypted data deduplication schemes has become an urgent problem that cloud service providers need to solve.In this thesis,the following four solutions are proposed to solve some problems in the existing encrypted data deduplication schemes.(1)Based on the password authentication key exchange protocol,bilinear mapping and homomorphic encryption,an encrypted data deduplication scheme without any trusted third party is proposed,which contains only two parties,namely users and cloud server provider.Because of this,the security of scheme significantly improved.(2)An encrypted data deduplication scheme is presented based on an offline key distribution protocol via the bilinear mapping and broadcast encryption.In this scheme,the initial uploader is able to deliver the encryption key to the subsequent uploader via the CSP in an offline manner.(3)Based on ciphertext policy attribute-based encryption and bilinear mapping,an encrypted data deduplication scheme with dynamically updated ownership of data is proposed.This scheme not only realizes the repeated deletion of encrypted data,but also designs a lightweight ownership updating algorithm to ensure the forward security and backward security of the system.