Cloud computing means entrusting data to information systems that are managed by external parties on remote servers, in the "cloud", raising new privacy and confidentiality concerns. We propose a general technique for designing cloud services that allows the cloud to see only encrypted data, while still facilitating some data-dependent computations. The technique is based on key translations and mixes in web browsers. We focus on a particular kind of software-as-a-service, namely, services that support applications, evaluations, and decisions. Such services include job application management, public tender management (e.g., for civil construction), and conference management. We identify the specific security and privacy risks that existing systems pose. We propose a protocol that addresses them, and forms the basis of a system that offers strong security and privacy guarantees. We express the protocol and its properties in the language of ProVerif, and prove that it does provide the intended properties. We describe an implementation of a particular instance of the protocol called ConfiChair, which is geared to the evaluation of papers submitted to conferences. 2. We propose a general protocol that provides secrecy and unlinkability properties for cloudbased competition management, relying on a trusted competition manager and in-browser key translation (section 3) 3. We show how the desired privacy properties can be formally expressed and automatically verified with ProVerif (section 4) 4. We present the implementation of a privacy-supporting system for conference management (ConfiChair), which is based on our general protocol (section 5). Contributions 1-3 are a generalization of a specific protocol for conference management and of its verification, that we have proposed in [9] .
Arapinis et al. REF propose and formally analyse ConfiChair, a cryptographic protocol that addresses secrecy and privacy risks coming from a malicious cloud.
Privacy-supporting cloud computing by in-browser key translation
Journal of Computer Security
Journal of Computer Security
Computer Science