Forward Secure Online/Offline Key Policy Attribute-Based Encryption with Keyword Search

Industrial Internet of Things (IIoT) is a cloud-based system that collects data from devices, and key policy attribute-based keyword search (KP-ABKS) scheme enables fine-grained keyword search over the encrypted data obtained from IIoT devices. However, in existing KP-ABKS schemes, the trapdoor’s lifetime is generally infinite, meaning that the trapdoor can be used for searching at any time. This poses a risk to the disclosure of the keyword in the trapdoor. Additionally, the inherent computational and storage requirements of KP-ABKS impose a significant burden on IIoT terminal devices. In this paper, we propose a new cryptographic primitive called forward secure online/offline key policy attribute-based keyword search (FS-OO-KPABKS), which supports both forward security and online/offline secret key generation and encryption. We provide a rigorous security model that the FS-OO-KPABKS scheme achieves selective security against chosen keyword attacks (SCKA) in the standard model. Furthermore, theoretical analysis demonstrates that our scheme exhibits remarkable efficiency in online secret key generation and, online encryption and search execution, and hence shows good adaptability in the IIoT thanks to its unbounded attribute universe.