FFH-ABE: Fast File-Hierarchy Attribute-Based Encryption Scheme for the Internet of Things

With the rapid deployment of cloud computing and the exponential growth of data, it is a trend for users with limited resources to outsource the tasks of data sharing and platform building to proxy cloud service providers (PSCPs). However, the openness and uncontrollability of the computing environment pose a great threat to users’ sensitive data and personal privacy. The highly functional encryption mechanisms based on ciphertext-policy attribute-based encryption (CP-ABE)  were proposed to address these problems of secure data sharing in the IoT. In this paper, we propose an efficient and flexible file-hierarchy CP-ABE scheme based on the linear secret sharing scheme (LSSS) matrix. First, we design a hierarchical access control matrix using LSSS that can encrypt and decrypt multiple files simultaneously with a single access policy. Second, we employ multiple access control matrices to make access control more flexible. Third, we prove that our scheme is secure against the chosen-plaintext attack (CPA) under the decisional bilinear Diffie-Hellman (DBDH) assumption. Furthermore, we optimize the access control structure, and conduct experimental comparisons with the existing schemes by theoretical analysis and experimental simulation, showing that our scheme achieves significant improvements in both computation and storage costs.