Efficient Attribute-Based Searchable Encryption With Policy Hiding Over Personal Health Records

Due to the introduction of cloud computing in healthcare services, personal health records (PHRs) have being uploaded to cloud servers in increasing numbers. Since data confidentiality requirements exist, data owners should encrypt their PHRs in advance of transmitting them to a cloud server. Attribute-based encryption with keyword search (ABKS) technique ensures that the encrypted PHRs are able to retrieved by other data users whose attributes match access polices granted by data owners. However, access polices are public in most existing ABKS schemes, which can reveal sensitive information contained in PHRs. In this article, we provide an efficient ABKS scheme with policy hiding for PHRs that implements the following features. (1) The fine-grained access control is achieved where data owners can authorize which data users can retrieve encrypted PHRs. (2) The access policy is hidden to safeguard sensitive information from being leaked. (3) The costs of storage and computation do not grow linearly as the number of attributes increases. The security of the presented ABKS scheme is reduced to the truncated q-DABDHE assumption and the DDH assumption. Its performance is also demonstrated by our extensive simulation experiments.