Abstract Basic configuration in quantum cryptography is a point-to-point quantum key distribution. In networks with quantum key distribution, the keys received on different network segments are different. For information encryption between arbitrary network nodes it is necessary to have agreement of the keys distributed in different segments of network through a public classical communication channel. The secrecy criterion for keys independently distributed in different network segments is formulated in terms of the trace distance. These are the so-called ε –secret keys. The paper deals with the issue of the secrecy of the agreed keys. We propose the method of secret keys agreement in which the agreement of two ε 1 , ε 2 –secret keys distributed in different segments leads to a common ( ε 1 + ε 2 ) –secret key. It is shown that in order to agreed common key will be ε –secret, it is sufficient that the keys on the individual segments are ε /2–secret.
Abstract Basic configuration in quantum cryptography is a point-to-point quantum key distribution. In networks with quantum key distribution, the keys received on different network segments are different. For information encryption between arbitrary network nodes it is necessary to have agreement of the keys distributed in different segments of network through a public classical communication channel. The secrecy criterion for keys independently distributed in different network segments is formulated in terms of the trace distance. These are the so-called ε –secret keys. The paper deals with the issue of the secrecy of the agreed keys. We propose the method of secret keys agreement in which the agreement of two ε 1 , ε 2 –secret keys distributed in different segments leads to a common ( ε 1 + ε 2 ) –secret key. It is shown that in order to agreed common key will be ε –secret, it is sufficient that the keys on the individual segments are ε /2–secret.
The quantum cryptography technology allows key distribution in individual segments of a network in a point–point configuration; then, keys in individual segments are used to protect traffic between any nodes of the network, which are not connected directly by a quantum channel. Correspondingly, the problem of negotiation (distribution) of keys between separate segments of the network appears. In this work, the problem of the transmission of an independent key through trusted nodes of the quantum network, between which keys are provided as a result of quantum key distribution, is considered. Quantum keys are used to encrypt the transmitted key. The transmitted key can be encrypted by both the block cipher and the one-time pad. It has been shown that the complexity of search for the key transmitted through the network depends on the imperfection of the external key and quantum keys as well as on the imperfection of the block cipher, i.e., on the average probability of collisions in the block cipher. The complexity in the case of the encryption of the transmitted key by the one-time pad depends only on the imperfection of the transmitted key and encryption keys. Perfect keys keep the perfectness of the transmitted key. In the block cipher, the transmitted key is no longer perfect even with the perfect keys in the measure of difference of the block cipher from the one-time pad. It has also been shown that the larger the number of collisions of the block cipher, i.e., the smaller the number of ciphertexts covered by the block cipher, the smaller the number of search steps required to find the key.
The quantum cryptography technology allows key distribution in individual segments of a network in a point–point configuration; then, keys in individual segments are used to protect traffic between any nodes of the network, which are not connected directly by a quantum channel. Correspondingly, the problem of negotiation (distribution) of keys between separate segments of the network appears. In this work, the problem of the transmission of an independent key through trusted nodes of the quantum network, between which keys are provided as a result of quantum key distribution, is considered. Quantum keys are used to encrypt the transmitted key. The transmitted key can be encrypted by both the block cipher and the one-time pad. It has been shown that the complexity of search for the key transmitted through the network depends on the imperfection of the external key and quantum keys as well as on the imperfection of the block cipher, i.e., on the average probability of collisions in the block cipher. The complexity in the case of the encryption of the transmitted key by the one-time pad depends only on the imperfection of the transmitted key and encryption keys. Perfect keys keep the perfectness of the transmitted key. In the block cipher, the transmitted key is no longer perfect even with the perfect keys in the measure of difference of the block cipher from the one-time pad. It has also been shown that the larger the number of collisions of the block cipher, i.e., the smaller the number of ciphertexts covered by the block cipher, the smaller the number of search steps required to find the key.
Quantum key distribution (QKD) protocols generate a same secret key at two nodes which are at different locations. Such key is used to encrypt and decrypt messages for unconditionally secure communications through a classical channel. Originally, QKD protocols are designed to work between two nodes which are directly connected through a point-to-point quantum channel. Currently, commercial QKD systems have limited range and key rate. To increase key rate and extend range, the key generated by QKD at one end node is relayed hop-by-hop to the other end node through multiple trusted nodes. In a QKD network with multiple pairs of communicating nodes, routing deals with the issue of deciding for each pair, which trusted nodes are used to form a path connecting the end nodes. This paper presents an overview of QKD and highlights the differences between QKD routing as compared to classical routing. The challenges of QKD routing are presented. Existing works dealing with the challenges are surveyed. This paper ends with a discussion on remaining research issues.
This work presents quantum key distribution protocols (QKDPs) to safeguard security in large networks, efficiency is improved as the proposed protocols contain the fewest number of communication rounds and two parties can share and use a long-term secret Key. Quantum cryptography is basically based on a trusted channel in communication between two parties compared to classical channel. Recently, Quantum Key Distribution (QKD) has become more secure transmission method used to transmit secret key between two legitimate parties. This paper discusses the implementation of (QKD) protocol with the existence of an eavesdropper. The implementation simulates the communication of two parties who wish to share a secret key with the existing of eavesdropper. The existing of eavesdropper is simulated with two kinds of attacks, which is used as parameter to measure the length of final key agreed by both authenticated parties at the end of the communication.
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 ε = ε K + ∑ i = 1 N s ε i -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 .
The purpose of quantum key-distribution is for two or more correspondents, who share no secret information initially, to agree on random keys, which remain secret against attacks from more powerful analytic or computational tools. Quantum cryptography protocols can be designed to offer guaranteed security services in optical communication networks. The paper briefly outlines a general procedure for modeling and simulation of quantum key distribution protocols in multiple-access networks. Each communication network model is assumed to be composed of communication nodes (stations) that are connected by links. There are three basic communication node models, which are quantum transmission (QT), quantum reception (QR), and quantum transmission reception (QTR) nodes. In the models, fiber optic channels (links) are assumed to be used for connecting communication nodes.