RPC-MPKET: Location-based revocable encryption with ciphertext equality test for multi-user Internet of Vehicles

Internet of Vehicles (IoV) systems can improve urban traffic efficiency. However, cloud-based IoV systems also introduce numerous security challenges. In particular, securely searching IoV’s encrypted sensor data (e.g., traffic flows, GPS coordinates) demands specialized Searchable Encryption (SE) schemes to balance retrievability and security. Therefore, SE has become an important research area. Public Key Encryption with Equality Test (PKEET) offers a simple yet useful mechanism that not only encrypts data, but also allows equality tests on ciphertexts. However, existing multi-user PKEET techniques cannot achieve authorization revocation. Once a cloud server obtains the authorization trapdoor, it can permanently test ciphertext without permission at any time. In this paper, we introduce a new concept of Multi-User Public Key Encryption with Equality Test supporting Revocation in Public Channel (RPC-MPKET) to adapt to cloud-based multi-vehicle IoV environments. The revocation mechanism from identity-based encryption is introduced into our scheme. The time-based private key is updated periodically and supports public channel transmission, reducing the establishment cost while ensuring privacy and security. Our scheme satisfies ciphertext one-wayness under chosen ciphertext attack (OW-CCA) and ciphertext indistinguishability (IND-CCA) against different adversaries in the random oracle model. In terms of efficiency, our scheme achieves encryption, decryption, and testing through the root-finding method of Vandermonde matrices without bilinear pairing operations, enhancing computational efficiency. Finally, we demonstrate its practicality in a cloud-based vehicular network environment through a series of experiments conducted on cloud servers.