‘Pushing’ keys through quantum networks and the complexity of search of the true key

Abstract

The question of the transfer of an external independent key through trusted nodes, between which the keys obtained during the quantum key distribution are located, is investigated. It is shown that when pushing external ɛ K -secret key through a chain of trusted nodes connecting separate segments with ɛ i -secret keys obtained by quantum key distribution, the final matched key between the extreme nodes of the network turns out to be -secret (where i is the number of the network segment, N s is the number of network segments connecting the extreme nodes), provided that the external key is encrypted on the ɛ i –secret keys in the one-time pad mode. It is also shown that for any measurements of an eavesdropper providing him with additional information about the keys, the complexity of partial/complete search for an matched key is determined by the secrecy parameter ɛ.