A provably secure free-pairing certificateless searchable encryption scheme

The protection of user data and privacy is becoming more critical because they mainly come from different sources, such as the Internet of Things. The searchable encryption (SE) primitive is a potential candidate who can guarantee data privacy while maintaining the search capability. The majority of known SE methods rely on the bilinear pairing operation, which is an expensive operation compared to other cryptographic operations. Therefore, bilinear-based SE may not be suitable for deployment on constraint devices with limited processing power. In addition, most of the schemes presented in the literature were vulnerable to different types of attacks, such as keyword guessing attacks. We tackle these issues by presenting a pairing-free public key encryption with keyword search and does not require a secure channel. The proposed scheme is proven in the random oracle model to be secure against various keyword guessing attacks, based on the hardness of solving the discrete logarithm and the computational Diffie–Hellman problems. These results are concluded by thoroughly analyzing the proposed scheme and five other state-of-the-art schemes recently presented in the literature. Finally, based of the performance analysis, where the experiments are conducted using three different sets of parameters for the elliptic curve, combined with three hash functions that were advised by NIST to satisfy the different security requirements, we observe that the proposed scheme does not require much communication costs and is somewhat fast in executing the different algorithms. Moreover, the proposed scheme guarantees the security requirements and makes it semantically ciphertext-indistinguishability, trapdoor-indistinguishability secure, and resilient to online and offline keyword guessing attacks.