The study is devoted to the development and formalization of integrated approaches to building a secure and efficient information infrastructure of a smart city, with an emphasis on threat modeling, implementation of cryptographic methods of identity management and assessment of the sustainability of human capital as a key resource. A conceptual model of a smart city architecture based on fundamental elements of the infrastructure is presented. Mathematical models for analyzing the impact of information threats on the system dynamics are developed. An innovative technology of end-to-end identification based on multi-level hashing and set theory is proposed and formalized in detail to ensure the security of personal data in distributed registries. In addition, an analysis of the methodology for a comprehensive assessment of the sustainability of human capital development in the context of smart city digitalization at the global, macro and micro levels is carried out. The results of the study demonstrate potential ways to improve the security, reliability and socio-economic sustainability of smart city ecosystems.