Abstract: Ciphertext-policy attribute-based encryption provides one-to-many access control for IoT systems based on cloud storage. However, there are some problems such as high cost and coarse granularity in the existing scheme. Therefore, a compact attribute-based encryption scheme supporting computing outsourcing with fog computing technology is proposed. It shortens the length of the keys and ciphertexts to reduce the storage cost of the client, transfers part of the computing to fog nodes to improve encryption and decryption efficiency, has more abundant policy expression ability, and can quickly verify the correctness of outsourcing decryption. The scheme is proved secure against indistinguishably chosen-ciphertext attack. Furthermore, performance analysis shows that our proposal can provide efficient access control for data storage when terminal device is limited in fog computing.

Key words: fog computing, CP-ABE, constant-size keys and ciphertext, computing outsourcing