Catch 22 of cryptography -"Before two parties can communicate in secret, they must first communicate in secret". The weakness of classical cryptographic communication systems is that secret communication can only take place after a key is communicated in secret over a totally secure communication channel. Here comes quantum key distribution which takes advantage of certain phenomena that occur ...

This paper compares the popular quantum key distribution (QKD) protocol BB84 with the more recent Kak’s three-stage protocol and the latter is shown to be more secure. A theoretical representation of an authentication-aided version of Kak’s threestage protocol is provided that makes it possible to deal with man-in-the-middle attack.

The progress in silicon planar device technologies has led single-photon avalanche diodes (SPAD) to emerge from the laboratory research phase and be commercially available from various manufactures. QKD systems can already exploit the available planar Si-SPAD devices, but they set strong demand for improved features and performance. A response can be given by new developments in a dedicated sil...

This paper introduces a variation on Kak’s three-stage quanutm key distribution protocol which allows for defence against the man in the middle attack. In addition, we introduce a new protocol, which also offers similar resiliance against such an attack.

Terrestrial QKD channels can connect two links with a maximum distance of few hundred kilometres. In the case of fibre links, this is due to the signal attenuation in the fibre; in the case of free-space link the losses are due to atmospheric turbulence and absorption. Free-space optical terminals exploiting satellite-based relays are the only resource that can enable global scale quantum key d...

Jonathan Barrett, ∗ Roger Colbeck, † and Adrian Kent 4, ‡ Royal Holloway, University of London, Egham Hill, Egham TW20 0EX, U.K. Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland. Centre for Quantum Information and Foundations, DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, U.K. Perimeter Institute for Theoretical Ph...

We discuss a quantum key distribution scheme in which small phase and amplitude modulations of quantum limited, CW light beams carry the key information. We identify universal constraints on the level of shared information between the intended receiver (Bob) and any eavesdropper (Eve) and use this to make a general evaluation of the security and efficiency of the scheme.

We introduce a protocol with a reconfigurable filter system to create non-overlapping single loops in the smart power grid for the realization of the Kirchhoff-Law-Johnson-(like)-Noise secure key distribution system. The protocol is valid for one-dimensional radial networks (chain-like power line) which are typical of the electricity distribution network between the utility and the customer. Th...

We develop the concept of quantum carrier and show that messages can be uploaded and downloaded from this carrier and while in transit, these messages are hidden from external agents. We explain in detail the working of the quantum carrier for different communication tasks, including quantum key distribution, classical secret and quantum state sharing among a set of n players according to gener...

The lists of bits processed in quantum key distribution are necessarily of finite length. The need for finite-key unconditional security bounds was recognized long ago, but the theoretical tools have become available only very recently. We provide finite-key unconditional security bounds for two practical implementations of the Bennett–Brassard 1984 coding: prepareand-measure implementations wi...