The Internet of Medical Things represents a pivotal application of Internet of Things technology in Healthcare 4.0, offering substantial practical benefits in enhancing medical quality, reducing costs, and minimizing errors. In history, researchers have proposed numerous privacy-preserving authentication schemes to safeguard Internet of Medical Things applications. Nevertheless, due to design shortcomings, existing solutions still encounter significant security and performance challenges, rendering them impractical for real-world use. To resolve the issue, this work introduces a novel practical Internet of Medical Things-based smart healthcare system, leveraging a pairing-free certificateless signature scheme and hash-based message authentication code. Through formal security proofs under standard cryptographic assumptions, and performance analysis, our scheme demonstrates enhanced security while maintaining desirable computational and communication efficiency.

The large-scale deployment of Internet of Things (IoT) technology across various aspects of daily life has significantly propelled the intelligent development of society. Among them, the integration of IoT and named data networks (NDNs) reduces network complexity and provides practical directions for content-oriented network design. However, ensuring data integrity in NDN-IoT applications remains a challenging issue. Very recently, Wang et al. (Entropy, 27(5), 471(2025)) designed a certificateless aggregate signature (CLAS) scheme for NDN-IoT environments. Wang et al. stated that their construction was provably secure under various types of security attacks. Using theoretical analysis methods, in this work, we reveal that their CLAS design fails to meet unforgeability, a core security requirement for CLAS schemes. In particular, we demonstrate that their scheme is vulnerable to a malicious public-key replacement attack, enabling an adversary to produce authentic signatures for arbitrary fraudulent messages. Therefore, Wang et al.’s design cannot achieve its goal. To address the issue, we systematically examine the root causes behind the vulnerability and propose a security-enhanced CLAS construction for NDN-IoT environments. We prove the security of our improved design under the standard security assumption and also analyze its practical performance by comparing the computational and communication costs with several related works. The comparison results show the practicality of our design.