THEOREM ABOUT KEY CAPACITY OF A COMMUNICATION NETWORK

Abstract

Introduction : An important aspect of cryptographic telecommunication systems is the encryption key control problem. The most complicated stages in its solution are the safe generation of the keys, their distribution, and their delivery to legitimate subscribers via protected communication channels, which is fairly expensive, sometimes slow and not always possible. As an alternative, the keys can be generated by transferring information via telecommunication channels, being possibly exposed to a violator. The known estimations of information efficiency look like a solution of sophisticated information theory problems for certain ways of open key coordination between two legitimate subscribers. Efficiency estimations for the conditions of network key generation are not known. Purpose : A s trictly conclus ive search for potential estimates of information efficiency of open network key gener ation. Results : Within the formulated statement of the problem, we have proposed a violator model and a network channel connectivity model which is a combination of a broadcast channel connecting three legitimate subscribers and an intercept channel at the output of which the violator controls the transferred information. The information exchange is based on the proposed models of a random coder and deterministic decoder with a specially developed asymptotic method of key generation. In order to assess the process, we introduce a system of quality indicators and requirements which differs from the known ones by its definition of “information” speed of network key generation. We also introduce a term of key network capacity which determines the asymptotic information efficiency of the key generation. We have formulated and rigorously proved a theorem about key capacity. The boundary values have been substantiated . Practical relevance : The obtained results develop the known scientific achievements in the field of open key coordination theory and can be used by specialists in the design and development of key control subsystems in modern cryptographic information security systems which provide closed network information exchange.