Critical information infrastructures of countries and they unions means information systems, telecommunication network, automated control systems operating in the spheres of health care, science, transport, telecommunications, energy, industry, financial market, of state and municipal administration, state security, the country's defense capacity, justice, law and order and other sensitive areas for the public. Therefore, the elements of critical information infrastructures and their information should be reliably protected, taking into account the requirements of national and / or union documents. Platforms on which elements of critical information infrastructures are created and will function must also meet these requirements. Mistakes in the creation of platforms for critical information infrastructures create threats of irreparable damage to countries and their unions. The article describes the methodological foundations for the creation of national protected hardware and software platforms for critical information infrastructures that meet the regulatory requirements for information security, the general and functional requirements of the owners of elements of critical information infrastructures. The principles were formulated, compliance with which ensures the creation of platforms with specified special properties. Generalized the experience of creating a Russian protected hardware and software platform "Sintez-HSP", certified for information security requirements, with high functionality, providing technological and import independence of the critical information infrastructure of the Russian Federation, which can be applied by other countries.