Abstract: The rapid development of quantum information technology will have a profound impact on information and communication technology and cyber security. Quantum computing poses new challenges to traditional cryptography and also stimulates the development of quantum cryptography based on quantum physics. This paper begins with the historical evolution of cryptography and introduces the basic concepts from classical cryptography to quantum cryptography. Then it analyzes the quantum security problems and its urgency caused by quantum computing, and further explores its countermeasures and solutions.

Key words: quantum security, quantum key distribution, post-quantum cryptography