Encryption and Fragmentation for Data Confidentiality in the Cloud

Cloud computing has emerged as a successful paradigm allowing individual users as well as companies to resort to external providers for storing/processing data or making them available to others. Together with the many benefits, cloud computing introduces however new security and privacy risks. A major issue is that the data owner, storing data at external providers, loses control over them, leaving them potentially exposed to improper access, use, or dissemination. In this chapter, we consider the problem of protecting confidentiality of sensitive information when relying on external cloud providers for storing and processing data. We introduce confidentiality requirements and then illustrate encryption and data fragmentation as possible protection techniques. In particular, we discuss different approaches that have been proposed using encryption (with indexing) and fragmentation, either by themselves or in combination, to satisfy confidentiality requirements.