The Research And Implementation Of Public Key Encryption With Equality Test In Cloud Environment

With the popularity of the cloud computation,people would store the data in the cloud servers rather than store in the localhost for reducing the local storing expense and facilitate the sharing of data.However,saving in the cloud servers,the data would bring the owner the uncontrollability.If storing in the cloud servers after encrypting,it is not easy to retrieve the data.With the searchable encryption proposed,the users can enjoy the convenience of the cloud storage and promise the data safety.Public key encryption with equality test,supporting check whether two cipertexts using different public keys are encryptions from the same message,is an embranchment of searchable encrypiton.But aim to public key encryption with equality test,offline message recovery attack brings a higher requirement of the development of the searchable encryption.In the meanwhile,among the scheme of public key encryption with equality test,the authorization mechanism just suuports two levels of authorization and six types of authorization.Two levels of authorization contain user-level authorization which can not control the range of the ciphertext for the tester and cipertext-level authorization which is too cumbersome to operation.This paper mainly discusses about the the research and implement of public key encryption with equality test.Based on the traditional schemes of public key encryption with equality test,proposing the schemes make the improvement in some aspects and implement.The first scheme is that improvement dual server public key encryption with equality test,unlike the schemes of the past which are two-server public key schemes against offline message recovery attack using the smooth projective hash function and lacking the decryptionmechanism.This scheme also resist the offline message recovery attack by using dual server,and fulfill the decryption mechanism,proved the scheme satisfies CCA security for the ciphertext security,which can extend the more scenarios.The second scheme is that tag-based public key encryption with equality test,analysed the merits and demerits of the two levels of authorization.Combining their advantages and the concept of the tag,it can decrease the operation cumbersome as well as can control the range of the ciphertext for the tester with user-level authorization.The third part is the implements of public key encryption with equality test.The first system is the identification system for protecting the usename security,using two-server in parallel to protect the moblie number as the usename and implement the identity authentication,in the meanwhile,resisiting the offline message recovery attack.The second system is the ciphertext retrieval system supporting the linear relation query,setting two-server in series to against the offline message recovery attack,can check whether the cipertexts exist the linear relation without the decryption.The third system is the ciphertext retrieval system supporting the cipertext-level authorization,each ciphertext has one and only trapdoor.Without the trapdoor,tester hardly test the ciphertext successful.Therefore,it can limit the tester to excute the equality test between the ciphertexts with the trapdoors.