A key-revocable attribute-based encryption for mobile cloud environments

In this paper, we propose a new Attribute-Based Encryption (ABE) scheme applicable to mobile cloud environments. A key issue in mobile cloud environments is how to reduce the computational cost on mobile devices and delegate the remaining computation to cloud environments. We also consider two additional issues: an efficient key revocation mechanism for ABE based on a concept of token-controlled public key encryption, and attribute hiding encryption from a cloud server. To reduce the computational cost on the client side, we propose an efficient ABE scheme jointly with secure computing on the server side. We analyze the security of our ABE scheme and evaluate the transaction time of primitive functions implemented on an Android mobile device and a PC. The transaction time of our encryption algorithm is within 150 msec for 89-bit security and about 600 msec for 128-bit security on the mobile device. Similarly, the transaction time of the decryption algorithm is within 50 msec for 89-bit security and 200 msec for 128-bit security.