Supporting Complex Queries and Access Policies for Multi-user Encrypted Databases

Cloud computing is an emerging paradigm offering companies (virtually) unlimited data storage and computation at attractive costs. It is a cost-effective model because it does not require deployment and maintenance of any dedicated IT infrastructure. Despite its benefits, it introduces new challenges for protecting the confidentiality of the data. Sensitive data like medical records, business or governmental data cannot be stored unencrypted on the cloud. Companies need new mechanisms to control access to the outsourced data and allow users to query the encrypted data without revealing sensitive information to the cloud provider. State-of-the-art schemes do not allow complex encrypted queries over encrypted data in a multi-user setting. Instead, those are limited to keyword searches or conjunctions of keywords. This paper extends work on multi-user encrypted search schemes by supporting SQL-like encrypted queries on encrypted databases. Furthermore, we introduce access control on the data stored in the cloud, where any administrative actions (such as updating access rights or adding/deleting users) do not require re-distributing keys or re-encryption of data. Finally, we implemented our scheme and presented its performance, thus showing feasibility of our approach.