Research On Cryptographic Schemes With Equality Test Based On Cipertext

Cryptography is used more and more widely in modern life,especially in online payment system,cipher landing system and information encryption in mobile communication and so on.With the development of social needs,public key cryptography has come to a new challenge.For example,in the outsourced database,the data is stored in the form of encryption.The data should be divided into storage,when the statistics of some data are needed to be extracted.However,the classical schemes can not get corresponding links about plaintexts according to the the ciphertext without knowing the decryption key.In 2010,Yang et al.proposed a new cryptographic primitive-public key encryption with equality test(PKEwET).In the case of no decryption,the scheme can determine whether two different ciphertexts contain the same plaintext.Then,many cryptographers pay attention to it.But at present,most of the PKEwET schemes are based on the bilinear pairing and the computational cost is higher than the model exponents.Therefore,it is very important to study the more efficient PKEwET schemes.This paper focuses on the PKEwET schemes.Try to improve the PKEwET schemes.The aim is to design the more efficient and more practical PKEwET schemes.From the security,storage space and computing cost,we have designed four types of PKEwET schemes.The details and contributions of this paper are described as follows:(1)We have designed a PKEwET scheme based on a straight line.The scheme supports the following four types of flexible authorization:user level authorization,ciphertext level authorization,special user level authorization and ciphertext-user level authorization.In the test algorithms,the scheme is separated from the bilinear pairing,and the equality test of ciphertext is carried out only through a straight line.Therefore,compared to other PKEwET schemes,the scheme has many advantages.For example,the storage space of ciphertext is small and computational complexity is very low.It is more practical than others.(2)We have designed a PKEwET scheme which can resist the quantum attacks.First,we analyze the security of the existing PKEwET schemes,point out that these PKEwET schemes will be broken under the quantum computer.Then,combined the difficult assumptions of the non-commutative cryptography,we design a new PKEwET scheme.It is the first PKEwET scheme which can resist the quantum attack.In addition,the computational complexity is very low.(3)We propose the key-policy attribute-based encryption with equality test.Compared to other schemes,the scheme is more flexible in authorization and there is a better application prospect in cloud computing.In addition,we propose the authorization security model.In order to prove the authorization security of the scheme,a new difficult assumption is put forward:the twin Decisional Bilinear Diffie-Hellman problem.Based the difficult assumption,we prove the security of authorization.Other schemes have no proof about it.Finally,we show the efficiency analysis of the scheme.(4)We present a new PKEwET scheme with validation.The scheme is designed based on ray and has high efficiency.Moreover,in the previous schemes,the authorized party did not verify the validity of the ciphertext before the equality test.It is unsafe.Therefore,on the basis of previous work,we improve the previous schemes.It allows the authorized party to verify the validity of the ciphertext before carrying out the equality test and then does the equivalent test of the ciphertext.