Blind decryption for cloud computing

Cloud computing is a tremendous opportunity for both enterprises and end users. Cloud users can benefit from the possibility of remote processing in order to outsource their data and infrastructure; that is why many companies have chosen to adopt cloud-deployed solutions such as remote databases, mail servers, and connected applications. However, the cloud fails to provide sufficient security measure to preserve the privacy of the data even from the service providers. Therefore, the research community has assigned to this topic the utmost attention by proposing several solutions like blind processing. This latter is based on homomorphic encryption schemes and allows performing operations on encrypted data without decryption. This way it is possible to protect users' privacy even from the cloud provider since we only publish an encrypted form of the sensitive data. But, most of the proposed solutions only deal with the case of a mono-setting environment where one user collaborates with one server, whereby the multi-user topology reveals another kind of issues such as key sharing and concurrent access. In this paper, we propose a blind decryption technique based on homomorphic encryption that allows not only a user but multiple users to manage the same encrypted data without sharing the secret key. The proposed protocol could be utilized to build various kinds of cloud applications which require the collaboration of several users like remote databases, files sharing, and video-on-demand services.