The Research Of Searchable Public Key Encryption Against Offline Message Recovery Attack

With the rapid development of cloud storage technology and Internet,an increasing number of individuals or groups move their huge data to the cloud servers in order to avoid the management and maintenance of complicated local data and access or share data from anywhere at any time.However,the date face serious security issues due to it loses the control of the data owners.It is a good way for users to encrypt their date to ensure the data security.For encrypted data,the data in storage and transmission process is secure as long as date owners protect their keys,and only the data owners and authorized users can access plaintext.This way can eliminate the all possibility of data leakage theoretically.Unfortunately,traditional encryption technology cannot provide some common functions,for instance,search on ciphertexts.To solve this issue,searchable encryption is proposed.It is a basic technology for owners to guarantee their data security and support computing on ciphertext.Public key encryption with equality test(PKEET)is a type of searchable encryption of multi-user environment,which allows a tester to check whether two ciphertexts encrypted under different public keys as well as the same public key contain the same message via test algorithm.However,PKEET is vulnerable to offline message recovery attack(OMRA)due to the desired this functionality.Note that this type of attack is inherent in searchable encryption and is an open problem until now.In this paper,we discuss the method of resisting OMRA and propose three schemes to withstand OMRA.The first scheme uses front server and back server sitting and can support checking two types of equation on the ciphertexts of Mi and M2:aM1 + bM2 + c = 0 or M1a×M2b×c =1,where a and b are integers.The second scheme uses left server and right server and can support both three types of authorization and checking two types of equation on the ciphertexts of Mi and Mj under different public keys:aMi = bMj or Mia =Mjb,where a and b are integers.The third scheme uses traditional single server sitting,introduces the concept of group into PKEET firstly to against OMRA and supports authorization without trapdoor,and gives new security models.In fact,the group idea in the third scheme can be used to construct other sercure searchable encryption schemes when consider multi-user environments.