Zero Trust Security in Modern Networks: A Survey of Applications, Challenges, and Future Directions

The zero trust paradigm experiences widespread adoption in leading domains such as cloud computing, Internet of Things, and blockchain. Nonetheless, actual deployment faces substantial technical and managerial challenges. A comparative analysis of the traditional perimeter-defense security model and the zero trust model explores their distinctions in identity management, fine-grained authorization, and dynamic access control. The analysis emphasizes the technical solutions and empirical outcomes of implementing zero trust security mechanisms in multi-cloud environments, smart device networks, and decentralized systems. The study demonstrates that zero trust, through continuous authentication, the principle of least privilege, and multilayered dynamic security policies, effectively mitigates internal threats and lateral movements, yet it still encounters significant challenges related to performance overhead, deployment complexity, and standardization. Finally, the paper outlines future optimization directions and research hotspots, thereby providing theoretical reference and practical guidance for further exploration in related fields.