Data Encryption And Cipher Index Technology Supporting Accurate Query In The Das Model

Query percessing over the encrypted relation is the main challenge in the DAS model. Nowadays, the existing encryption schemes and cipher index schemes have defect in the lowness of query hit rate which leads to the crowdedness in network transmission. It is the key for this problem to reduce the redundant data in query results. A synthetical encryption scheme on attribute-grain and a synthetical cipher index technology in the DAS model to eliminate redundant data are presented through considering numeric data and character data respectively. The details are as follows.Firstly, through analyzing and comparing database encryption schemes, cipher index schemes and query technologies over cipher-text in being, conclude their advantages and disadvantages.Secondly, the classification of the DAS model is studied. The confidence relation, among the data owner, the database service provider and the querier, is analyzed, then the new classification on the DAS model is given. Furthermore, the divisions of every entity in all classifications are discussed in details.Thirdly, the encryption method on the encrypted relation in the DAS model is studied. According to the query requirement, the data of owner's is concluded into two classifications, that is, the data of various fuzzy querying and that of numeric comparison. Next, encrypt the two-type data respectively. For the former, k-mapping encryption scheme for character data is proposed, which determine k mapping values for each character composed the domain of attribute through the mapping function. For the later, an order preserving encryption scheme is used in the encrypted relation. Based on above, a synthetical encryption scheme on the attribute-grain is presented. Meanwhile, the effectiveness and security are analyzed. At last, the cryptogram query strategy as well as experiment verification is presented.Finally, the cipher index on the encrypted database in the DAS model is studied through analyzing the defect in the existing bucket partition cipher index schemes. A synthetical cipher index applying to the DAS model is presented. Moreover, the effectiveness and security are analyzed. At last, its cryptogram query strategy of the synthetical cipher index scheme in the DAS model as well as experiment verification is given.