Managing and Querying Encrypted Data

Encryption is a popular technique for ensuring confidentiality of sensitive data. While data encryption is able to enhance security greatly, it can impose substantial overhead on the performance of a system in terms of data management. Management of encrypted data needs to address several new issues like choice of the appropriate encryption algorithms, deciding the key management architecture and key distribution protocols, enabling e?cient encrypted data storage and retrieval, developing techniques for querying and searching encrypted data, ensuring integrity of data etc. In this chapter, we give an overview of the state-of-the-art in some of these areas using the “Database As a Service” (DAS) as the prototype application. We especially concentrate on techniques for querying encrypted data and summarize the basic techniques proposed for SQL queries over encrypted relational data, keyword search over encrypted text data and XPath queries over encrypted XML data. We also provide brief summaries of works relating to other issues mentioned above and provide further references to the related literature.