Privacy-Preserving and Pairing-Free Multirecipient Certificateless Encryption With Keyword Search for Cloud-Assisted IIoT

Nowadays, cloud-assisted Industrial Internet of Things (IIoT) has become pervasive in modern enterprises, because it supplies a promising way to transform the operation mode of existing industrial facilities, to enhancing the production efficiency and lowering the manufacturing cost. In order to preserve the privacy of enterprises, sensitive industrial data needs to be encrypted prior to being uploaded to the cloud. Recently, certificateless encryption with keyword search (CLKS) was introduced to resolve the problem of encrypted data retrieval in cloud-assisted IIoT. However, the existing CLKS schemes only support a single-recipient keyword search and need to depend on the costly bilinear pairing that is disliked by the resource-constrained IIoT devices. Moreover, most of the existing CLKS schemes are vulnerable to the keyword guessing attack, and thus fail to protect the privacy of searched data. In this article, we develop a privacy-preserving and pairing-free multirecipient CLKS scheme for cloud-assisted IIoT. The proposed scheme has the following merits: 1) supporting multirecipient keyword search function; 2) requiring no costly bilinear pairing operations; and 3) providing resistance against keyword guessing attacks. The performance comparison and analysis demonstrate that it is more efficient than the existing CLKS schemes and is appropriate for the cloud-assisted IIoT.