Designated server proxy re-encryption with boolean keyword search for E-Health Clouds

E-Health Cloud can provide remote, accurate, real-time, intelligent information services for healthcare. Despite the benefits brought by data outsourcing, it may also cause data breaches and compromise user privacy. Searchable encryption can provide data security and search services in the encrypted data domain. However, in E-Health Cloud, users may have some other special needs, such as sharing their health information with doctors during the treatment period and updating the data access right when they transfer from one hospital to another. Some works introduced the primitive proxy re-encryption with public keyword search (Re-PEKS) to meet the above needs. However, the state-of-the-art solutions cannot support expressive boolean query, and its search cost time increases linearly with total number of outsourced documents, this is very impractical in huge E-Health Cloud system. An efficient Re-PEKS scheme termed PRTDs is proposed in this article to address this problem. PRTDs supports sub-linear boolean query, time controlled data sharing, and re-encryption to change data users simultaneously. To compare PRTDs with the most advanced time-enabled Re-PEKS scheme, we also implement exhaustive comparative experiments on HUAWEI Cloud with the Enron dataset, and the results show that PRTDs has a better performance on encryption and searching.