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Cloud Spreadsheets Supporting Data Processing in the Encrypted Domain

Security has become one of the main barriers for the adoption of cloud services. A range of legal initiatives that require support mechanisms such as access control and data encryption have been proposed to ensure privacy for data moved to the cloud. Although these mechanisms are currently feasible in situations in which the cloud acts as a mere data storage system, they are insufficient in more complex scenarios requiring processing in external cloud servers. Several new schemes have been proposed to overcome these shortcomings. Data Processing in the Encrypted Domain (DPED) permits arithmetic operations over ciphered data and the generation of encrypted results, without exposure of clear data. In such a set-up, the servers have no access to the information at any point of the process. In this paper we describe, as a case study of secure cloud data processing, a cloud spreadsheet that relies on DPED libraries to perform operations in the encrypted domain. Tests performed on local servers and in the Google cloud through the Google App Engine platform show that representative real applications can benefit from this technology. Because the proposed solution is PaaS-oriented, developers can apply the libraries to other applications.