Quantum cryptography is different from traditional cryptography, which relies on physics rather than mathematics as the key aspect of security mode. In essence, quantum cryptography is an unbreakable cryptographic system based on the application of a single photon and its inherent quantum properties, because the quantum state of the system cannot be determined without disturbing the system. Theoretically, other particles can also be used, but photons have all the required mass and their behavior is relatively easy to understand. At the same time, they are also the most promising information carriers in high-bandwidth communication media optical cables. Nowadays, quantum cryptography refers to the use of the "mysterious" association between a pair of entangled particles in a quantum entangled state to generate a key. If a third party intervenes, this association will be destroyed and discovered, and then the generated key will be invalid and start over. Only when both parties participate can the key be generated smoothly, that is, the generation of this key will never be known to the third party, thus achieving the purpose of confidentiality. With the intervention of a third party, the key cannot be generated-this is the core of quantum cryptography.