Study Of Database Watermarking Scheme In Order-preserving Encrypted Domain

As cloud computing develops rapidly,massive sensitive information have been stored and issued over the network in the form of database.Since the security threats exist,it's not obviously wise to directly deliver the database to a third party,such as database as a service(Daa S).Information hiding technology in encrypted domain,which well combines the advantages of encryption and information hiding,can carry out information hiding processing for integrity authentication or copyright protection.Order-preserving encryption(OPE)as an encryption scheme for database(which allows comparison operations on encrypted data without decryption),is more suitable for cloud computing.In this paper,innovatively combining the advantages of database encryption and database watermarking,two database watermarking scheme in order-preserving encrypted domain is presented to against the trouble in plaintext domain.1)A database authentication watermarking algorithm in order-preserving encrypted domain is proposed.Firstly,a certain attribute column is encrypted with a secure OPE scheme.Then the encrypted data are divided into groups for DCT operations.The AC coefficients are selected to generate authentication watermark bits by means of hash algorithm.The watermark bits are embedded into the DC coefficients by using QIM algorithm.After that,the encrypted and watermarked database can be obtained after executing inverse DCT operations.By matching the hash value of the AC coefficients and the extracted watermark bits from the DC coefficients,database integrity authentication can be achieved.This algorithm has solved the trouble of exploring massive redundancy in plaintext domain.Moreover,the watermark embedding will not affect the use of database,and the original database can be restored faultlessly after decryption.Experimental results show that this algorithm can effectively detect different tampering operations to achieve the purpose of integrity authentication.2)A database robust watermarking algorithm in order-preserving encrypted domain is proposed.Firstly,a certain attribute column is encrypted with a secure OPE scheme,and divided into groups by using hash function.Then in circular histogram model,the histogram center of mass of each group and its mean direction ?i are computed.Similarly,the histogram center of mass and mean direction ? are calculated over all the tuples.According to ?,the model is divided into two codebooks(C0 and C1).So in order to encode 0 or 1,?i will be rotated to the left(?-?)or to the right(? +?)of this frontier,by modifying the cipher values.The algorithm combines the feature of OPES,which ensure that the invariant ciphertext order as well as the strong robustness.Moreover,the original database can be restored faultlessly after decryption.Experimental results show that this algorithm has strong robustness to against most common attacks(i.e.,tuple insertion and deletion),and achieves the purpose of copyright protection.