We consider a multi-user quantum key distribution (QKD) system based on free-space optics (FSO) in terrestrial environment. Due to obstacles the signal path, FSO-QKD is heavily affected by decoherence and other harmful effects. In order avoid performance degradation, trusted nodes (TNs) are introduced QKD network. However, absence of alternative routes, classical data relayed same TN, which mak...

Steganography is the study of concealing and sending a secret message by making eavesdropper unaware its presence. First ever attempt to propose steganography via quantum key distribution (QKD) was made Martin in his paper where BB84 QKD used for communicating steganographic messages. The protocol have recently been found be insecure against detection based steganalysis attack which uses ambigu...

In recent years, determining the common information privately and efficiently between two mutually mistrusting parties have become an important issue in social networks. Many Private set intersection (PSI) protocols have been introduced to address this issue. By applying these protocols, two parties can compute the intersection between their sets without disclosing any information about compone...

Abstract Coherent-one-way (COW) quantum key distribution (QKD) held the promise of distributing secret keys over long distances with a simple experimental setup. Indeed, this scheme is currently used in commercial applications. Surprisingly, however, it has been recently shown that its rate scales at most quadratically system’s transmittance and, thus, not appropriate for distance QKD transmiss...

In this paper, we put forward a novel single-state three-party semiquantum key agreement (SQKA) protocol with three-particle GHZ entangled states first. Different previous quantum (QKA) protocols, the proposed SQKA can realize goal that party and two classical parties who only possess limited capabilities equally contribute to generation of shared private over channels. Detailed security analys...

In this paper, we propose a polar coding scheme for secure communication over the multiple-input, single-output, single-antenna eavesdropper (MISOSE) fading channel. We consider the case of block fading channels with known eavesdropper channel state information (CSI) and the case of fading channels with known eavesdropper channel distribution information (CDI). We use the artificial noise assis...

This paper studies remote state estimation in the presence of an eavesdropper. A sensor transmits local state estimates over a packet dropping link to a remote estimator, while an eavesdropper can successfully overhear each sensor transmission with a certain probability. The objective is to determine when the sensor should transmit, in order to minimize the estimation error covariance at the re...

A quantum key distribution (QKD) system may be probed by an eavesdropper Eve by sending in bright light from the quantum channel and analyzing the backreflections. We propose and experimentally demonstrate a setup for mounting such a Trojan-horse attack. We show it in operation against the quantum cryptosystem Clavis2 from ID Quantique, as a proof-of-principle. With just a few back-reflected ph...

Fuchs et al. (Phys Rev A 56:1163, 1997, https://doi.org/10.1103/PhysRevA.56.1163 ) suggested an optimal attack on the BB84 protocol, where necessary and sufficient condition for optimality involves joint Hilbert space of sender attacker. In this work, we propose a refined criteria involving attacker only. It reveals that (non-zero) overlaps between attackers post-interactions states must be equ...

Website fingerprinting attacks allow a local, passive eavesdropper to identify a user’s web activity by leveraging packet sequence information. These attacks break the privacy expected by users of privacy technologies, including low-latency anonymity networks such as Tor. In this paper, we show a new attack that achieves significantly higher accuracy than previous attacks in the same field, fur...