A Survey on Querying Encrypted Data for Database as a Service

Using database encryption to protect data in some situations where access control is not solely enough is inevitable. Database encryption provides an additional layer of protection to conventional access control techniques. It prevents unauthorized users, including intruders breaking into a network, from viewing the sensitive data. As a result data keeps protected even in the incident that database is successfully attacked or stolen. However, data encryption and decryption process result in database performance degradation. In the situation where all the information is stored in encrypted form, one cannot make the selection on the database content any more. Data should be decrypted first, so an unwilling tradeoff between the security and the performance is normally forced. The appropriate approaches to increase the performance are methods to deal directly with the encrypted data without firstly decrypting them. This paper while introduce some methods for searching on encrypted data, provides a comparison study between current methods in terms of performance and security.