the article considers the development trends of the high-tech industry of quantum communications. The most popular topologies of quantum communication networks are described, including those with trusted intermediate nodes. The methods of interaction between nodes of the backbone quantum-cryptographic network are given and the main methods of ensuring secure transmission in such networks are presented. A simplified scheme for distributing a quantum secret key between the end segments of the backbone telecommunication network using trusted intermediate nodes is considered. Possible data leakage channels in the general structure of quantum-cryptographic networks are described.

Keywords: quantum communications, quantum key, network topologies, trusted nodes

The article reports about approximation algorithm for Integer Factoriation Problem (IFP) using reduction to optimizing case of SAT problem with 3 literals per clause (MAX-3SAT). A continuous functional that equivivalent MAX-3SAT is builded and solved by simple iteration method with variable neighboordood search and Bayesian rounding. It shown that global minimum of the functional cannot be reached in almost samples because local extremums but arguments of ones can be compared with the exact solution. The experiments show that the developed gybrid algorithm improves earlier version developed by authors. Also this method is analyzed by quantum channels defense In systems of quantum key distribution. A typical structure of one is described.

Keywords: Integer Factorization Problem, an optimzed version of SAT problem (MAX-3SAT), various neighboorhood search, continuous functional of MAX-3SAT representation, quantum key distribution

The article considers the description of the design and construction of the Ultra high frequency mixer on a combination and slotted a microstrip transmission line. Presents the methodology and results of the experiment by analysis the amplitude characteristic. It is shown that the conversion loss equal to 9 dB, the dynamic range of not less than 60 dB, the upper limit of the linearity of the amplitude characteristic is 1mW.

Keywords: mixer, Schottky barrier diodes, microstrip line, slotline, decimeter range, amplitude response, Ultra high frequency.

The article considers the problem of secrecy in the distribution of the encryption key. The structure of the stand quantum cryptographic network based on commercial autocompensation quantum key distribution system with phase coding states of photons was proposed. The process of integration a quantum key in encryption protocols telecommunications network are described. The results of experimental studies on the use of quantum keys in a data network.

Keywords: Quantum key, cryptography, protocol, telecommunications network, encryption.