OOABKS: Online/offline attribute-based encryption for keyword search in mobile cloud

Abstract Mobile cloud computing is a new computing method for mobile applications, which enables storage and computation migration from mobile users to resource-rich and powerful cloud server. More and more mobile phone users share their information through the mobile cloud. As the cloud server is not fully trusted, for security and privacy concerns, data owners usually encrypt their data before outsourcing them to the cloud server. In response to above questions, some attribute-based keyword search (ABKS) schemes have been proposed. However, the key generation, encryption and decryption for ABE take up a lot of computing resources in these schemes. In this paper, we propose an online/offline attribute-based keyword search scheme for mobile cloud (OOABKS). We use online/offline ABE technology and outsource ABE technology to reduce the online calculation cost and the local calculation cost of mobile users. And, we implement the fine-grained access control for the user. Security analysis demonstrates that our scheme can achieve trapdoor unlinkability, keyword security, data privacy security and search controllability. Efficiency analysis shows, in terms of functionalities and the computation overhead, OOABKS is more practical and efficient than existing approaches.