A Synthetical Cipher Index Technology and its Cryptogram Query Strategy in Outsourced Databases

Cipher index is a well established technology for improving query efficiency. However, the existing index schemes have defect of lowness in query hit rate which leads to Internet crowdedness. It is the key for this problem to reduce the redundant tuples in query results. A synthetical cipher index technology to eliminate redundant tuples is presented through considering numeric data and character data respectively. Firstly, according to the query requirement, users´ data is concluded into two classifications: the data of various fuzzy querying and that of numeric comparison. Next, cipher indices are established respectively. For the former, a newly cipher index scheme is presented, which determine k character indices for each character composed attribute domain through a mapping function. For the later, an order preserving encryption scheme is used as a cipher index scheme. Meanwhile, the effectiveness and security are analyzed. Finally, the cryptogram query strategy in outsourced databases is presented.