Decoy states have recently been proposed as a useful method for substantially improving the performance of quantum key distribution QKD . Here, we present a general theory of the decoy state protocol based on only two decoy states and one signal state. We perform optimization on the choice of intensities of the two decoy states and the signal state. Our result shows that a decoy state protocol ...

Success of any eavesdropping attack on a quantum cryptographic protocol can be reduced by the legitime users if they partially compare their data. It is important to know for the legitime users what is (necessary and enough) amount of data which should be compared to ensure that (possible) illegitime user has an arbitrary small information about the rest of data. To obtain such amount the legit...

There has been much interest in quantum key distribution. Experimentally, quantum key distribution over 150 km of commercial Telecom fibers has been successfully performed. The crucial issue in quantum key distribution is its security. Unfortunately, all recent experiments are, in principle, insecure due to real-life imperfections. Here, we propose a method that can for the first time make most...

A trusted quantum relay is introduced to enable quantum key distribution links to form the basic legs in a quantum key distribution network. The idea is based on the well-known intercept/resend eavesdropping. The same scheme can be used to make quantum key distribution between several parties. No entanglement is required.

Quantum mechanical properties of communication lines may be lead to new possibilities in the security of key distribution. By taking advantage of basic quantum mechanical principles, it may be possible to create secure systems that rely upon the physics of the system rather than computational or mathematical methods for security. In this paper, three possible protocols for quantum key distribut...

We propose the subcarrier domain of multicarrier continuous-variable (CV) quantum key distribution (QKD). In a multicarrier CVQKD scheme, the information is granulated into Gaussian subcarrier CVs and the physical Gaussian link is divided into Gaussian subchannels. The sub-channels are dedicated for the conveying of the subcarrier CVs. The angular domain utilizes the phase-space angles of the G...

Chi-Hang Fred Fung, ∗ Bing Qi, † Kiyoshi Tamaki, ‡ and Hoi-Kwong Lo § Center for Quantum Information and Quantum Control, Department of Electrical & Computer Engineering and Department of Physics, University of Toronto, Toronto, Ontario, Canada NTT Basic Research Laboratories, NTT corporation, 3-1,Morinosato Wakamiya Atsugi-Shi, Kanagawa, 243-0198; CREST, JST Agency, 4-1-8 Honcho, Kawaguchi, Sa...

We study the practical effectiveness of privacy amplification for classical key-distribution schemes. We find that in contrast to quantum key distribution schemes, the high fidelity of the raw key generated in classical systems allow the users to always sift a secure shorter key if they have an upper bound on the eavesdropper probability to correctly guess the exchanged key-bits. The number of ...

First implementations of Quantum-key Distribution Cryptosystems have shown the need to use a storage device on which to keep a copy of the key that such cryptosystems create and distribute between a pair of users. Such users must be able to access their device to take enough key to code and decode the messages they send each other over a public channel. Because of the importance of the key stor...

Secure key establishment in wireless sensor networks has been shown to be efficient. For sake of computation power, predistribution of symmetric keys is recommended. In such schemes, a set S of keys is used and each deployed node knows a subset of S. However, the capture of nodes can quickly lead to the corruption of a significant part of the network and solutions like multi-deployment have bee...