To perform Quantum Key Distribution, the mastering of the extremely weak signals carried by the quantum channel is required. Transporting these signals without disturbance is customarily done by isolating the quantum channel from any noise sources using a dedicated physical channel. However, to really profit from this technology, a full integration with conventional network technologies would b...

A simple technique to secure quantum key distribution relay networks is presented here. The paper introduces the concept of logical channels that uses a random dropout scheme. The paper also presents an enhanced protocol for key distribution in the relay networks. Previous techniques relied on creating distinct physical paths to create shares. Hence the compromise of one relay must compromise t...

We present a new protocol for quantum key distribution using discrete phase-shift encoding with continuous variables. The novelty of the protocol is multi letter alphabets represented by coherent states of light with fixed amplitude and variable phase. Information is encoded in the phase of a coherent states which can be chosen from a regular discrete set consisting of an arbitrary number of le...

The Kish Key Distribution (KKD) system has been proposed as a classical alternative to quantum key distribution, making use of temperature-matched thermal noise. Previous analyses assume instant propagation of signals along the cable connecting the two users.We describe a new attack that takes an advantage of propagation delays. At the start of each bit period, the noise temperature will then b...

In previous quantum key distribution (QKD) protocols, information is encoded on either the discrete-variable of single-photon signal or continuous-variables of multi-photon signal. Here, we propose a new QKD protocol by encoding information on continuous-variables of a single photon. In this protocol, Alice randomly encodes her information on either the central frequency of a narrowband single ...

The two-way continuous-variable quantum key distribution (CVQKD) systems allow higher key rates and improved transmission distances over standard telecommunication networks in comparison to the one-way CVQKD protocols. To exploit the real potential of two-way CVQKD systems a robust reconciliation technique is needed. It is currently unavailable, which makes it impossible to reach the real perfo...

Turbo coding is a powerful class of forward error correcting codes, which can achieve performances close to the Shannon limit. The turbo principle can be applied to the problem of side-information source coding, and we investigate here its application to the reconciliation problem occuring in a continuous-variable quantum key distribution protocol.

This paper presents a server-based hybrid cryptographic protocol, using quantum and classical resources, to generate a key for authentication and optionally for encryption in a network. A novel feature of the protocol is that it can detect a compromised server. Additional advantages are that it avoids the requirement for timestamps used in classical protocols, guarantees that the trusted server...