Certificateless Encryption Supporting Equality Test with Cryptographic Reverse Firewalls in Smart City

In the context of smart cities, sensors are pivotal for the collection and analysis of health data within smart healthcare systems. Despite their importance, securing this data for cloud storage poses significant challenges, particularly in terms of data searchability and encryption. Our paper introduces a novel solution, namely certificateless encryption supporting equality test with cryptographic reverse firewalls (CLE-ET-CRF). This protocol allows cloud servers to perform equality tests on encrypted data without compromising its confidentiality, effectively mitigating risks like offline message recovery attacks (OMRA) and algorithm substitution attacks (ASAs). By eliminating the need for traditional certificate management and addressing key escrow concerns, CLE-ET-CRF provides a secure, efficient, and privacy-preserving mechanism for managing healthcare data in smart city ecosystems. Our evaluation confirms that the protocol meets the high standards required for privacy and efficiency in smart healthcare applications.