Hierarchical and non-monotonic key-policy attribute-based encryption and its application

Hierarchical-authority attribute-based encryption (HABE) can resolve the performance bottleneck of the key generation center in the traditional attribute-based encryption (ABE) system. HABE has numerous applications, such as cloud computing and smart grid systems. Nevertheless, almost all of the existing HABE schemes are in the ciphertext-policy setting and do not support non-monotonic access structures. In this work, we propose the first key-policy hierarchical-authority ABE with non-monotonic access structures, dubbed KP-HABE-NMaCS, which supports the authority key delegation, constant size ciphertexts and the large universe simultaneously. We further define the security model of KP-HABE-NMaCS and prove the selective security of it in the standard model. Then we optimize our scheme to realize the outsourced decryption. Subsequently, we present the detailed theoretical analysis of our constructions and the existing HABE constructions in computation and storage costs, and meanwhile implement ours and conduct a series of experiments. Both results indicate that our KP-HABE-NMaCS construction makes improvements in expressiveness and features, and achieves efficiency comparable to the previous HABE constructions. Furthermore, they also show that our extension construction is suitable for resource-limited applications. Eventually, we explore how to apply our KP-HABE-NMaCS to build an ABE with equality test and time-based authorization.