Smart cities have a unique characteristic – the integration and deployment of Information and Communication Technology (ICT) services and innovations to handle complex data in storage devices and during city-wide transmission. Technologies adopted in smart cities are mostly state-of-the-art and may not be found outside these cities. Smart cities today have been used as testbeds or showcases for new technologies (e.g., 5G, 6G, Terahertz) for which security and privacy are still uncertain. Valuable data underpinned by those technologies can be at risk of various attacks. Security with privacy is an essential key to drive a smart city. Security and privacy issues do not only affect a smart city as a whole, but also its smart elements including buildings, factories, healthcare systems, education, transportation, etc.

Particularly in smart factories, Internet of Things (IoT), Industrial IoT (IIoT), and Cyber-Physical Systems currently lack adequate access control and anti-malware and operate 24/7. They are vulnerable to attacks such as distributed denial-of-service (DDoS) attacks. Regarding a virtualization environment for an internet operator, Network Functions Virtualization (NFV), along with Software-Defined Networking (SDN), also encounter attacks and the solution to this is still unclear. In smart buildings, new usable factors of authentication and types of biometric methods are needed to speed up the authentication process. In smart health, data confidentiality is vital for privacy law compliance such as General Data Protection Regulation (GDPR) in the EU and personal data protection acts in many countries. Cryptography and new security architecture for specific contexts can support privacy and law compliance. Technologies for data integrity, such as blockchain, maintain the accuracy and consistency of data, but the actual implementation (e.g., e-voting in a smart government) cannot confirm data availability and confidentiality due to lack of secure design on the front end and other non-blockchain-related parts. Consequently, security with privacy is an essential topic to ICT audiences with an emphasis on smart cities.

The aim of this Special Issue is to collate original research and review articles emphasizing security and privacy in smart cities. Case studies and best practices are also welcome.

Potential topics include but are not limited to the following:

• Security in IoT, IIoT, and Cyber-Physical Systems in smart cities and industry 4.0
• Security in NFV, SDN, and other virtualization environments in smart cities
• New methods of user identification including new factors of authentication, new types of biometric authentication, and new digital identification applied to smart cities
• Security in online working spaces including meetings and online learning in smart environments
• Information-hiding techniques for data confidentiality in smart cities
• Fault-tolerant design techniques for data availability and data integrity in smart cities
• Security in testbed technology including 5G, 6G, and Terahertz
• Security solutions to support security and privacy law compliance
• Security and privacy standardization in smart cities
• Case studies and best practices of successful implementation in a unique smart city domain