Research On Keyword Search Encryption Scheme In Cloud Computing

As a new application mode of network,cloud computing can provide users with data storage and transaction access service.It has developed rapidly in recent years.Currently,more and more sensitive information such as personal health record,enterprise data are centrally stored on the cloud servers.In order to ensure that sensitive information of users is not compromised,sensitive data must be encrypted before being uploaded to the cloud server.As a kind of “one to more” encryption method,attribute-based encryption can not only provide the data confidentiality but also realize expressive fine-grained access control.Therefore,it is regarded as one of the most suitable encryption in the cloud computing environment.However,as the files in the cloud server are stored in ciphertext,how to search for files containing specific keywords in a large volume of ciphertext files becomes extremely difficult.In order to solve the problem of ciphertext search in cloud,it is necessary to design an efficient and searchable attribute-based encryption scheme.Nevertheless,it will confront with a series of problems when searchable attribute-based encryption scheme is put into practice: Because the cloud server is untrusted,the cloud server may return incorrect or incomplete files during the search,how to ensure that the cloud server returns the correct search results.In addition,because the cloud environment has the characteristic of openness,any data owner can upload data to the cloud server,how to ensure that the source of the data searched by the user is authentic and reliable.To solve the above problems,the main work of this thesis is:(1)This paper proposed a verifiable attribute-based multi-keyword search encryption scheme.In the new scheme,data owners to set access control for the encrypted data via the ciphertext-policy attribute-based encryption,which can classify the sensitive data and provide search services for users according to the access rights.Meanwhile,by setting an authentication tag with the reciprocal of data owner's secret value for each encrypted data,users can implement a one-time correctness verification of search results,which contain multiple ciphertext,but each ciphertext may come from different data uploader.In the random oracle model,the scheme achieves the unforgeable of the response,the confidentiality of keywords and selectively secure against chosen-keyword attack.(2)Based on attribute-based encryption and keyword search encryption technology,this paper proposed the concept of searchable attribute-based authenticated encryption,and established the corresponding security model.Then,we embed ingeniously search mechanism into attribute-based signcryption,constructed a concrete searchable attributebased authenticated encryption scheme.Finally,under the proposed security model framework,our scheme is proven to achieve ciphertext indistinguishability,ciphertext existential unforgeability,selective security against chosen-keyword attack and keyword secrecy.