Research On Searchable Encryption Key Technique In Cloud Environment

With the rapid development of cloud computing technology,more and more enterprises or individuals move their data into the cloud to reduce local management and maintenance burden.Despite the benefits of the cloud data service outsourcing model,confidentiality of remotely stored data on cloud sever is still a big concern.The most direct and simplest way is to encrypt the sensitive data by data user before it is outsourced to the cloud sever.However,the ciphertext encrypted by traditional encryption algorithm will lose some plaintext characteristics.For example,encrypted data make the traditional search methods based on plaintext keyword search useless.When the data users want to get interested ciphertext from the cloud,it is unrealistic to download the whole massive data,decrypt it locally,and then search for the desired results in the plaintext data.It is not only a way of wasting a lot of bandwidth resources,but also causes a huge local computing storage overhead.Therefore,searchable encryption technology that allows data users to securely search over encrypted data has attracted much attention.Aiming at the various practical settings and functional requirements,we have proposed the following searchable encryption schemes with different advantages.Firstly,the existing searchable encryption schemes cannot support ciphertext retrieval and fine-grained access control in sharing multi-owner setting at the same time.Therefore,we design an efficient cryptographic primitive called as multi-owner accredited keyword search over encrypted data scheme by combining linear secret-sharing technique with searchable encryption schemes,only the data users authorized by multi-owner could decrypt the search returned results.The scheme can protect the data security and privacy,and the experimental results show that the scheme has lower computational overhead and storage overhead.Secondly,as existing searchable encryption schemes in the multi-owner multi-user settings cannot achieve file-level access authorization and user revocation,and single keyword search has the defects of low efficiency.We propose a multi-keyword search over encrypted data with data user revocation scheme by combining ciphertext-policy attribute-based encryption technique with searchable encryption schemes.Authorized data users can obtain ciphertext encrypted by different data owners using different keys.Moreover,when the data user's attribute set is changed,the third party audit could achieve data user revocation by updating version information.The proposed scheme can resist the chosen keyword attack in random oracle.Moreover,the analysis of the experimental results demonstrates its high efficiency and feasiblility in practical application.Finally,the certificate-based searchable encryption schemes have large certificate management overhead,and the identity-based searchable encryption schemes inevitably incur the key escrow problem,and single keyword search will return a considerable number of irrelevant ciphertext.Therefore,we present a certificateless conjunctive keyword search over encrypted data scheme in the data exclusive scenario by combining certificateless encryption technology with searchable encryption schemes.The key generation center is responsible for generating the partial private key,and then the data user could generate the complete private key in the local by the partial private key and a secret value.Therefore,the key generation center cannot get the complete private key of data user.The scheme can tackle the key escrow problem,avoid using public key certificates and save bandwidth and computation resources.This scheme is secure against off-line keyword guessing attack in the standard model.Moreover,the analysis of the performance results shows that the scheme is highly efficient.