Certificateless searchable public key encryption scheme secure against keyword guessing attacks for smart healthcare

The smart healthcare system (SHS) provides a new information service mode. It greatly improves the diagnostic efficiency by monitoring patients' signs information via various wearable devices. To ensure the confidentiality of sensitive information, the security and privacy issues have drawn wide attention. The searchable encryption technology is suitable for addressing these issues, because it supports search over encrypted data and provides data privacy protection. Recently, many searchable public-key encryption (SPE) schemes have been designed to balance security and efficiency. However, these SPE schemes face the challenge of certificate management or key escrow. This is because they are constructed based on public key infrastructure (PKI) or identity (ID) cryptosystem. Meanwhile, most of SPE schemes are subject to great security threats, such as keyword guessing attacks (KGA). To resolve the above problems, this paper designs a secure certificateless SPE scheme for SHS, and this scheme does not require the use of secure channels, i.e., a SCF-CLSPE scheme. We prove that this SCF-CLSPE scheme can resist KGA and chosen keyword attacks (CKA) under standard model. In addition, the results of performance analysis indicate that this SCF-CLSPE scheme can achieve better efficiency.