Securing Smart City Ecosystems: A Taxonomy-Based Review of Emerging Technologies and Frameworks for Scalable Collaborative Services

The smart city concept integrates various collaborative services to enhance urban living. However, these services introduce significant security concerns, especially in authentication, authorisation, and access control (AAA). To address these security challenges, researchers must design and implement frameworks that safeguard data exchange between smart services. This paper offers a taxonomy-based review of current solutions, focusing on how emerging technologies like Blockchain, artificial intelligence (AI), quantum computing, and hybrid approaches address AAA concerns. We evaluate these technologies based on key factors such as confidentiality, integrity, availability (CIA), trust, privacy, and scalability. Through a systematic review of literature from 2017 to 2024, we classify and assess methods that strengthen authentication, optimise access control, and refine authorisation processes to mitigate risks in data sharing. A major contribution of this paper is the integration of case studies, demonstrating real-world applications of these technologies in smart city contexts. Additionally, we explore the applicability of these solutions, highlighting their challenges and future potential. This research also outlines future directions for building secure, efficient, and scalable smart city ecosystems, ultimately facilitating the development of adaptable frameworks for smart city services.