A secure method against frequency attack for pattern query on encrypted string data

Abstract

Using database encryption to protect data in somesituations where access control is not solely enough isinevitable. Database encryption provides an additional layer of protection to conventional access control techniques. Itprevents unauthorized users, including intruders breaking intoa network, from viewing the sensitive data. As a result dataremains protected even in the event that database issuccessfully attacked or stolen. However, encryption anddecryption of data result in database performancedegradation. In the situation where all the information isstored in encrypted form, one cannot make the selection on thedatabase content any more. Data should be decrypted first, soan unwilling tradeoff between the security and theperformance is normally forced. The appropriate approachesto increase the performance are methods to deal directly withthe encrypted data without firstly decrypting them. This paperintroduces a secure scheme against frequency attack forpattern query on encrypted string data. Proposed schemeprovides searching of arbitrary patterns in the fields' contentand supposes that the database management server isuntrusted and must be prevented from viewing the sensitivedata.