A Lightweight Access Control Scheme Supporting Policy Hidden Based on Path Bloom Filter

Traditional CP-ABE (Ciphertext-Policy Attribute-Based Encryption) schemes require the access policy to be uploaded to the cloud along with the ciphertext, but access policies often also involve some private information, which can lead to privacy leakage. Moreover, the decryption cost of the traditional CP-ABE scheme is too high, which is not suitable for source-limited end devices, such as medical monitoring terminals. To achieve policy hiding, decryption lightening, and high expressiveness of access policy all at the same time, we present a new CP-ABE scheme, in which a PBF (Path Bloom Filter) is designed based on ROBDD (Reduced Ordered Binary Decision Diagram). The ROBDD, as the access structure, can provide more vital and more flexible expressiveness. Then the PBF can hide the access policy, reduce the decryption cost, and accelerate the decryption speed. Analysis and simulation study show that our proposed scheme is secure under Decisional q-BDHE assumption and superior to previous schemes concerning computational cost.