In order to assess the susceptibility of the quantum key distribution (QKD) systems to the hacking attack including simultaneous and frequent system self-decalibrations, we analyze the stability of the QKD transmission organized in two commercially available systems. The first one employs non-entangled photons as flying qubits in the dark quantum channel for communication whereas the second one utilizes the entangled photon pairs to secretly share the cryptographic key. Applying standard methods of the statistical data analysis to the characteristic indicators of the quality of the QKD communication (the raw key exchange rate [RKER] and the quantum bit error rate [QBER]), we have estimated the pace of the self-decalibration of both systems and the repeatability rate in the case of controlled worsening of the dark channel quality.
In order to assess the susceptibility of the quantum key distribution (QKD) systems to the hacking attack including simultaneous and frequent system self-decalibrations, we analyze the stability of the QKD transmission organized in two commercially available systems. The first one employs non-entangled photons as flying qubits in the dark quantum channel for communication whereas the second one utilizes the entangled photon pairs to secretly share the cryptographic key. Applying standard methods of the statistical data analysis to the characteristic indicators of the quality of the QKD communication (the raw key exchange rate [RKER] and the quantum bit error rate [QBER]), we have estimated the pace of the self-decalibration of both systems and the repeatability rate in the case of controlled worsening of the dark channel quality.
We have performed a series of feasibility tests toward deployment of quantum key distribution (QKD) systems in commercial optical fiber TELECOM network. By monitoring of the operation of selected state-of-the-art QKD systems with a typical commercial imperfect communication line in the role of quantum dark channel we have assessed stability and reliability of two quantum cryptography systems, on nonentangled and on entangled photons. The quantum bit error was the main observed parameter which allowed for quantitative assessment of both systems operation efficiency and their resistivity to random perturbations including hacker attacks in noisy environment. The comparison of both systems with respect to their tolerance against noise and technical imperfections of a dark quantum channel has been presented.
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.
The present thesis aimed to evaluate the efficiency and resilience of quantum cryptographic systems against malicious attacks, with emphasis on Quantum Key Distribution (QKD).Initially, fundamental concepts of quantum computing and quantum inform ation were examined, such as qubits, superposition, entanglement, decoherence and quantum gates, in order to establish the necessary theoretical background for the reader.Subsequently, key QKD protocols, such as BB84, E91, B92, BBM92 and Decoy-State techniques, were analyzed and compared in terms of security, practical applicability, and sensitivity to different categories of attacks.The methodology of the thesis was based on bibliographic and comparative analysis, using evaluation metrics such as Quantum Bit Error Rate (QBER), secret key generation rate, throughput, transmission distance, and channel losses.The analysis showed that simple theoretical attacks, such as intercept-resend, are usually more easily detectable due to an increase in QBER, whereas practical implementation attacks, such as detector blinding, time-shift, trojan-horse and photon-number-splitting attacks, can be more dangerous because they exploit device imperfections and do not always cause an obvious increase in errors.In conclusion, the theoretical security of QKD protocols is strong; however, their actual efficiency depends on the quality of implementation, technological limitations and the balance between protection and the final rate of secure key generation.
In the last ten years, quantum computing has made substantial progress, presenting a strong challenge to traditional encryption methods that depend on solving discrete algorithmic problems. With the advent of the quantum era, conventional encryption methods are becoming more susceptible to attacks. This paper investigates possible attacks that exploit vulnerabilities in quantum cryptography, specifically investigating weaknesses in quantum key distribution (QKD) systems. The text thoroughly explores advanced attack strategies of photon number splitting highlight the existing vulnerabilities. The goal is to highlight the need for strong safeguards to protect against these threats, which requires continuous research and development to improve the robustness of quantum cryptography algorithms. The experimental investigation includes analyzing crucial parameters, including quantum channel length, loss, QKD protocol, quantum bit error rate (QBER), signal-to-noise ratio (SNR), as well as attack parameters such as probability of photon number splitting (PNS), eavesdropper distance, and detection efficiency. The evaluation includes performance indicators such as secure key rate, quantum bit error rate (QBER) vs distance, vulnerability to photon number splitting (PNS) attacks, and the influence on the pace of key generation.
The paper addresses the development of quantum networks (QNs) with entanglementbased Quantum Key Distribution (QKD) protocols.The entanglement (the correlation among the quantum states of several particles) is an essential principle of quantum mechanics.This property has a major impact on the fields of application of QKD systems, the secured cryptographic key exchange and passive attack detection, while it can also be applied in quantum teleportation.Starting from the existing achievements in Europe (a QN for connecting several cities in Randstad, one of the main metropolitan regions in the Netherlands), a case study for a simulated entanglement-based QN is presented, including an ideal scenario (with noiseless QKD) and a nonideal one (with noisy QKD).The experimental settings are differentiated through the link and node fidelity.The simulation process produces general statistics, sender statistics, receiver statistics, the QBER (Quantum Bit Error Rate) and also the raw keys as generated by the entanglement-based protocol.No post-processing (non-quantic) phase is considered for the analyzed setting.Such simulations are useful for properly adjusting the design of a QN while taking into account its expected performance with respect to the non-ideal use-cases with errors that could be caused by an imperfect hardware or by potential eavesdropping actions.
The overview of the current status of quantum cryptography is given in regard to quantum key distribution (QKD) protocols, implemented both on nonentangled and entangled flying qubits. Two commercial R&D platforms of QKD systems are described (the Clavis II platform by idQuantique implemented on nonentangled photons and the EPR S405 Quelle platform by AIT based on entangled photons) and tested for feasibility of their usage in commercial TELECOM fiber metropolitan networks. The comparison of systems efficiency, stability and resistivity against noise and hacker attacks is given with some suggestion toward system improvement, along with assessment of two models of QKD.