QUANTUM NETWORKS: KEY DISTRIBUTION VIA UNTRUSTED NODES

The aim of the research is to analyze the secrecy of quantum key distribution through untrusted nodes in quantum networks. Research method: the use of entropy uncertainty relations. Result(s) of the study: the secrecy of quantum key distribution through untrusted nodes in quantum networks is proved. The use of entropy uncertainty relations makes it possible to obtain an accurate solution for the length of the secret key in the single-photon case. A comparison with the exact solution for the BB84 protocol is made and the fundamental difference in the logical structure of proof of the secrecy of keys in these protocols is clearly shown, which, in our opinion, is important for the development of quantum cryptography systems. Scientific novelty: the article proves the secrecy of quantum key distribution through untrusted nodes in quantum networks.