A Comprehensive Analysis of Privacy-Preserving Solutions Developed for IoT-Based Systems and Applications

In recent years, a large number of Internet of Things (IoT)-based products, solutions, and services have emerged from the industry to enter the marketplace, improving the quality of service. With the wide adoption of IoT-based systems/applications in real scenarios, the privacy preservation (PP) topic has garnered significant attention from both academia and industry; as a result, many PP solutions have been developed, tailored to IoT-based systems/applications. This paper provides an in-depth analysis of state-of-the-art (SOTA) PP solutions recently developed for IoT-based systems and applications. We delve into SOTA PP methods that preserve IoT data privacy and categorize them into two scenarios: on-device and cloud computing. We categorize the existing PP solutions into privacy-by-design (PbD), such as federated learning (FL) and split learning (SL), and privacy engineering solutions (PESs), such as differential privacy (DP) and anonymization, and we map them to IoT-driven applications/systems. We further summarize the latest SOTA methods that employ multiple PP techniques like & varepsilon;-DP + anonymization or & varepsilon;-DP + blockchain + FL (rather than employing just one) to preserve IoT data privacy in both PES and PbD categories. Lastly, we highlight quantum-based methods devised to enhance the security and/or privacy of IoT data in real-world scenarios. We discuss the status of current research in PP techniques for IoT data within the scope established for this paper, along with opportunities for further research and development. To the best of our knowledge, this is the first work that provides comprehensive knowledge about PP topics centered on the IoT, and which can provide a solid foundation for future research.