Answering Aggregation Queries in a Secure System Model
As more sensitive data is captured in electronic form, security becomes more and more important. Data encryption is the main technique for achieving security. While in the past enterprises were hesitant to implement database encryption because of the very high cost, complexity, and performance degradation, they now have to face the ever-growing risk of data theft as well as emerging legislative requirements. Data encryption can be done at multiple tiers within the enterprise. Different choices on where to encrypt the data offer different security features that protect against different attacks. One class of attack that needs to be taken seriously is the compromise of the database server, its software or administrator.