Quantum key distribution (QKD) relies on the laws of physics to establish a symmetric binary key between remote parties. A QKD link involves the realization of a quantum channel for the transmission of quantum key material encoded in certain photon properties, as well as a public channel for verification of the exchanged key material. This paper deals with the mutual dependence of these channels and analyzes the impact of performance of both channels on the overall key material establishment process. This paper presents measurement data obtained under laboratory conditions as well as the results obtained by establishing a virtual QKD link. Despite the common beliefs that increased quantum bit error rate implies a larger amount of traffic on the public channel, our measurements prove the opposite. The obtained data clearly show that the public channel has a major impact on the overall performance of the QKD link.
Quantum key distribution (QKD) relies on the laws of physics to establish a symmetric binary key between remote parties. A QKD link involves the realization of a quantum channel for the transmission of quantum key material encoded in certain photon properties, as well as a public channel for verification of the exchanged key material. This paper deals with the mutual dependence of these channels and analyzes the impact of performance of both channels on the overall key material establishment process. This paper presents measurement data obtained under laboratory conditions as well as the results obtained by establishing a virtual QKD link. Despite the common beliefs that increased quantum bit error rate implies a larger amount of traffic on the public channel, our measurements prove the opposite. The obtained data clearly show that the public channel has a major impact on the overall performance of the QKD link.
Quantum Key Distribution (QKD), based on the laws of physics rather than the computational complexity of mathematical problems, provides an information-theoretically secure way of establishing symmetrical binary keys between two geographically distant users. This paper is oriented to the practical realization of QKD public channels which are usually implemented as overlay point-to-point connections. We address the problem of minimizing the key material consumption by changing packet overhead. Our results show that the efficiency of communication in overlay QKD networks may increase when packets of larger sizes are used. However, this tuning directly affects the performance of overall communication. We evaluated this approach using an overlay network module which was implemented in the NS-3 simulator. The obtained results can be used for other overlay networks as well.
Objective of this paper is the study of Quantum Key Distribution (QKD) protocols based on classical error-correcting codes. The Quantum Key Distribution (QKD) systems and related protocols, in particular conditions, can use the classic channel coding techniques, instead of quantum error-correcting codes, both for correcting errors that occurred during the exchange of a cryptographic key between two authorized users, and to allow privacy amplification, in order to make completely vain a possible intruder attempt. The secret key is transmitted over a quantum, and thus safe, channel, characterized by very low transmission rates and high error rates. This channel is safe for the properties of a quantum system, where each measurement on the system perturbs the system itself, allowing the authorized users to “feel” if there is any intruder listening. Moreover, as shown by accurate experimental studies, the communication channel used for quantum key exchange is not able to reach high levels of reliability (the Quantum Bit Error Rate (QBER) takes values between 0.05 and 0.11), both because of the inherent characteristics of the system, and of the presence of a possible attacker. Thus, in order to obtain acceptable residual error rates, it is necessary to use a parallel classical and public channel, conversely characterized by high transmission rates and low error rates, on which to transmit only the redundancy bits of systematic channel codes with performance possibly close to the capacity limit.
Abstract Quantum key distribution (QKD) is a method for securely exchanging keys based on quantum mechanics. QKD has been thoroughly examined for terrestrial and near-Earth satellite applications; however, forthcoming deep-space links are anticipated to experience considerable relativistic effects. Quantum states can be altered in these circumstances by relative motion between terminals and by gravitational effects, which may affect entan-glement, measurement outcomes, and overall security. The effectiveness of entanglement-based quantum key distribution (QKD) in relativistic motion is investigated in this work, with particular attention to deep-space optical communication. The quantum channel model includes Wigner rotations due to Lorentz transformations, polarization mixing due to Doppler shift, and redshift due to gravity. This method gives us new ways to analyze the quantum bit error rate (QBER), quantum entanglement fidelity, Bell inequality violation , and secret key rate. Our numerical simulations show that when the relative velocity becomes high enough, the polarization correlations start to break down significantly. This leads to more errors in the quantum bits, making it harder to generate a secure secret key. Even though quantum nonlocality persists at these speeds, relativistic effects make it much harder to actually extract a secure key.
A quantum key distribution protocol(QKD), known as BB84, was developed in 1984 by Charles Bennett and Gilles Brassard. The protocol works in two phases which are quantum state transmission and conventional post processing. In the first phase of BB84, raw key elements are distributed between two legitimate users by sending encoded photons through quantum channel whilst in the second phase, a common secret-key is obtained from correlated raw key elements by exchanging messages through a public channel e.g.; network or internet. The secret-key so obtained is used for cryptography purpose. Reconciliation is a compulsory part of post processing and hence of quantum key distribution protocol. The performance of a reconciliation protocol depends on the generation rate of common secret-key, number of bits disclosed and the error probability in common secrete-key. These characteristics of a protocol can be achieved by using a less interactive reconciliation protocol which can handle a higher initial quantum bit error rate (QBER). In this paper, we use a simple Bose, Chaudhuri, Hocquenghem (BCH) error correction algorithm with simplified syndrome table to achieve an efficient reconciliation protocol which can handle a higher quantum bit error rate and outputs a common key with zero error probability. The proposed protocol efficient in removing errors such that it can remove all errors even if QBER is 60%. Assuming the post processing channel is an authenticated binary symmetric channel (BSC).
Quantum Key Distribution (QKD) offers secure communication by leveraging core principles of quantum mechanics.Characterization of QKD system is fundamental for comparing the experimental results provided by researchers.Unfortunately, there is no standardized or unified approach; therefore, different researchers present results that provide heterogeneous information, making comparisons difficult.A systematic analysis of the literature is necessary to identify common approaches from a metrological perspective.This paper provides an overview of measurements used to characterize quantum channels, with a focus on parameters such as attenuation, polarization effects, and timing stability.To support this analysis, real-world case studies are examined.
The ever-increasing quantum computational power may pose a serious threat to classical Public Key Exchange (PKE) algorithms in the next few years. The need for quantum resilient key exchange schemes is becoming more topical as quantum computers become more powerful. Quantum Key Distribution (QKD) promises unconditionally secure key distribution between two remote parties. The distilled keys of a QKD link can be used by classical symmetric algorithms such as the Advanced Encryption Standard (AES). Unfortunately, QKD has come across some major limitations in distance reach and Secure Key Rates (SKR)s that make the idea of a global quantum secured network debatable. In this work, we propose a satellite assisted Key Encapsulation Mechanism (KEM) that takes advantage of the high security of a quantum AES-256-bit key encrypted link, to deliver secret keys through classical communication layer in high rates, using QKD only for link establishment. In this way, the keys produced by the QKD do not directly encrypt the data traffic, allowing therefore longer lifespans. This scheme would be able to support up to thousands terminal nodes with a total average SKR as low as 4.23 bps.