The smart city is now connected to the Internet of Things (IoT), actuators, sensors, and advanced communication smart technologies, such as 6G and Information Communication Technologies (ICT). It collects real-time informative data to enhance the efficiency of human services in various innovative city applications, including smart homes, smart transportation, smart farming, and others. These applications utilize emerging technologies like Blockchain, Artificial Intelligence (AI), and Federated Machine Learning (FML). However, smart city applications have challenges such as big data, communication latency, data authentication, centralization, computational bandwidth, security, and privacy. In this paper, we develop a smart city infrastructure based on Distributed Secure Communications and mitigate the above issues by decentralizing communication networks. Moreover, we provide service scenarios for developing a smart city infrastructure based on a cryptographic algorithm, Blockchain, and AI. The secret sharing algorithm is used at the edge layer for data encryption and decryption at various base stations. Blockchain technology offers a distributed data validation environment with verification nodes. Artificial Intelligence provides instant fog services, including self-management and dynamic fog services at the third layer. Finally, data is stored in the fourth layer in the different data centers.