Privacy of Outsourced Data

The amount of information held by organizations’ databases is increasing rapidly. To respond to this demand, organizations can either add data storage and skilled administrative personnel (at a high rate) or, a solution becoming increasingly popular, delegate database management to an external service provider (database outsourcing). In database outsourcing, usually referred to as Database As a Service (DAS), an external service provider provides mechanisms for clients to access the outsourced databases. A major advantage of database outsourcing is related to the high costs of in-house versus outsourced hosting. Outsourcing provides significant cost savings and promises higher availability and more effective disaster protection than in-house operations. On the other hand, database outsourcing poses a major security problem, due to the fact that the external service provider, who is relied upon for ensuring high availability of the outsourced database, cannot always be trusted with the confidentiality of database content.