Driven by fifth-generation technology (5G), the future Internet of Things (IoT) will need to support the interconnection between smart devices and systems. It will provide access to users everywhere at any time. Massive connectivity is one of the most important factors affecting the success of various IoT domains. For example, to apply future driverless cars in Internet of Vehicles (IoV), we need to ensure secure and robust connectivity between a large number of in-motion vehicles in a high-speed dynamic environment. How to design ultra-reliable and secure connectivity mechanisms/protocols in massive connected IoT has become a research hotspot.

Even so, large-scale interconnection and the broadcast nature of wireless communications make massive IoT applications vulnerable to internal threats and external attacks. Due to essential differences in scale and requirements, most standard security solutions designed for conventional wireless communication systems are not applicable to 5G-IoT applications. As a result, there are some IoT-specific security and protection challenges in massive connected IoT. Therefore, it is essential to pursue research on new security theories, architectures, and technologies in massive connected IoT. We can then build a more secure and robust IoT-connectivity system.

The aim of this Special Issue is to attract original research articles and review articles highlighting current and advanced security and privacy approaches in massive IoT. Both theoretical and practical perspectives are welcome.

Potential topics include but are not limited to the following:

• Dynamic vulnerability analysis and recovery for massive IoT
• High fault-tolerance connectivity mechanism in massive IoT
• Flexible and lightweight security mechanisms for massive IoT applications
• Mobile edge/fog computing advantages for secure interconnection in massive IoT
• Artificial intelligence (AI) and deep learning approaches for enhancing security in massive IoT
• IoT cooperation strategies for resisting attacks and preventing privacy leaks in massive IoT
• Blockchain technology for security in massive IoT
• Trust model and management in massive IoT
• Incentive mechanism for enhancing security in massive IoT
• Privacy protection for multi-entity and large-scale interconnection in massive IoT
• Intrusion detection and prevention for massive IoT
• Physical-layer security in massive IoT
• Optical wireless enhanced security in massive IoT (e.g., Li-Fi and infrared wireless)