Abstract: A system and method for secure communications over public networks. The system has a 3-layer hierarchical structure including a system kernel, secure servers and secure clients. Secure clients may communicate via trusted secure servers. Secure servers function according to the system secure operation rules and, in addition, each of them is configured to perform specific activities. System kernel serves the system to support its regular functioning. Any two secure data switching elements, which communicate within the system, have their own ciphering language, periodically substituted by another ciphering language.