Secure cipher index over encrypted character data in database

With the development of the information technology, database security draws more and more attention than before. It is desirable to store data in encrypted form to protect the sensitive data from various attacks. But the efficiency of DBMS will fall as the SQL clauses can not execute over the encrypted data directly. In this paper we propose a secure cipher index with great efficiency over the encrypted character data to improve the performance of the encrypted database. The radical idea is to map the character data in the database into its index value, and translate the SQL clauses into a usable form to execute over the index attribute. Hash key and confuse number are introduced to make the cipher index in security in our scheme. In this schema, the same character data in different rows has different index value and the index value has no statistical characteristic, so it can alleviate the problem of statistical attack and plain attack. When there is a query over the encrypted character attribute, we filter out the majority of useless tulpes through the index and only decrypt the remainder, which could reduce the decryption cost greatly and prevent the information leaking.