This paper presents a detailed theoretical and simulation-based comparison between the BB84 quantum key distribution (QKD) protocol and a proof-of-concept contextuality-based QKD protocol (CTX-QKD) under depolarizing noise. We begin by contrasting classical cryptography’s computational security with quantum cryptography’s information-theoretic guarantees. The physics of quantum cryptography, including superposition, entanglement, and the no-cloning theorem, is explored, followed by a mathematical analysis of BB84 and a proposed CTX-QKD framework. Performance metrics include the quantum bit error rate (QBER) for BB84 and contextuality violation measures for CTX-QKD, with confidence intervals derived from proper statistical bounds. A comprehensive simulation methodology using QuTiP, NumPy, and SciPy is described. Simulation results demonstrate that while BB84 shows expected noise tolerance up to 11% QBER, the CTX-QKD protocol maintains strong contextuality violations of the fundamental security condition under high noise conditions where BB84 fails. This study highlights the potential of contextuality as a resource for quantum cryptography and demonstrates a proof-of-concept for physics-based cryptographic security beyond traditional approaches.
This paper presents a detailed theoretical and simulation-based comparison between the BB84 quantum key distribution (QKD) protocol and a proof-of-concept contextuality-based QKD protocol (CTX-QKD) under depolarizing noise. We begin by contrasting classical cryptography’s computational security with quantum cryptography’s information-theoretic guarantees. The physics of quantum cryptography, including superposition, entanglement, and the no-cloning theorem, is explored, followed by a mathematical analysis of BB84 and a proposed CTX-QKD framework. Performance metrics include the quantum bit error rate (QBER) for BB84 and contextuality violation measures for CTX-QKD, with confidence intervals derived from proper statistical bounds. A comprehensive simulation methodology using QuTiP, NumPy, and SciPy is described. Simulation results demonstrate that while BB84 shows expected noise tolerance up to 11% QBER, the CTX-QKD protocol maintains strong contextuality violations of the fundamental security condition under high noise conditions where BB84 fails. This study highlights the potential of contextuality as a resource for quantum cryptography and demonstrates a proof-of-concept for physics-based cryptographic security beyond traditional approaches.
By utilizing concepts from quantum physics like entanglement and superposition, quantum cryptography is revolutionizing data security. This study focuses on the application of classical computational models for simulation-based analysis of Quantum Key Distribution (QKD) protocols, namely BB84 and E91. By taking use of quantum features, QKD makes secure key exchange possible and guarantees that any effort at eavesdropping may be identified because of the disruption of quantum states. In order to assess how quantum communication channels behave under different noise and attack scenarios, the study models and simulates these channels. The study evaluates the efficacy and robustness of BB84 and E91 protocols in practical network settings by contrasting their performance and error tolerance. In order to determine if integrating quantum-secured systems with current classical infrastructures is feasible, scalability issues are also investigated. These simulations’ outcomes shed light on feasible security levels, resource needs, and workable deployment tactics. In the end, this research highlights how quantum cryptography may advance the basis for next-generation secure information networks by bridging the gap between theoretical quantum security models and real-world communication systems with the use of strong simulation frameworks.
Quantum computing is advancing rapidly and thus is a major challenge to traditional schemes of cryptographies like RSA, and ECC that get their security on computational difficulty. In order to counter this challenge, a paradigm change to be proposed is quantum cryptography which is based on the application of the rules of quantum mechanics to a conditional security. In the paper, a design and implementation of an interactive simulation platform, which models two seminal quantum key distribution (QKD) protocols, namely, BB84 and E91, is proposed. Formulated with a modular architecture in Streamlit, the system allows users to simulate the transmission into qubit, visualize key pre-processing, study the quantum bit error rate (QBER) and detect any eavesdropping through CHSH inequality. The platform will be used to include functionality of real-time graphical dashboards, user authentication, and a comparative analysis segment to systematically review classical and quantum-related cryptographic methods. The effects of noise levels, adversarial interference on the QBER and key generation rates are verified, and this serves to confirm the resilience of quantum systems against eavesdropping. The tool can be used as an educational and a research tool since it offers an intuitive interface to learn the quantum concepts related to superposition or entanglement and simultaneously takes the user through the protocol functionality in different security regimes. The findings attest to the increased security capabilities of quantum cryptographic systems, thus making them a valid option in the future communication network during the post-quantum era.
Quantum Key Distribution (QKD) is increasingly recognized as a robust solution to the vulnerabilities posed by quantum computing to classical encryption systems. This paper presents a comprehensive investigation of the BB84 protocol, the foundational QKD scheme, through simulated quantum communication using IBM’s Qiskit framework. The study models quantum key exchange under both ideal and adversarial conditions, including channel noise and intercept-resend attacks. The Quantum Bit Error Rate (QBER) was measured as a function of noise intensity and eavesdropping, confirming that QBER increases predictably in compromised channels. A threshold of 11% QBER was used to determine the viability of secure key generation. Final key retention rates were analyzed across multiple channel scenarios, revealing BB84’s sensitivity to both photon loss and adversarial interference.\n\nSecurity vulnerabilities such as photon-number-splitting and detector blinding were assessed, and countermeasures including decoy-state protocols and authenticated classical channels were proposed. Four key performance graphs were generated to visualize system behavior under realistic operational conditions. The results support BB84’s theoretical advantage in ensuring information-theoretic security while acknowledging real-world limitations in transmission range and hardware reliability. The paper concludes by addressing future improvements in QKD systems, including satellite-based distribution, quantum repeaters, and device-independent implementations. Through simulation-driven analysis, this study validates BB84 as a practical defense against quantum-enabled attacks and underscores the need for continued development and standardization in post-quantum cryptographic infrastructure.
Abstract As quantum computing continues to demonstrate its potential to break through existing cryptographic systems, quantum key distribution (QKD) provides a novel approach to protect communications in the post-quantum era, but presents complex challenges in terms of research and widespread adoption. Although the resource-intensive nature of QKD setups limits experimental studies to specialized laboratories, we present an end-to-end simulation that models photon generation, transmission, and detection, thereby lowering the barrier to testing hypotheses regarding experimental setups under realistic conditions. In this study, a fiber optic-based simulation was utilized along with a quantum circuit and a detailed noise model within the BB84 protocol to recreate an experimental setup. Our BB84 simulation retained ≈50% of transmitted bits after sifting, matching the experimental expectations, and produced quantum bit error rate (QBER) values that rose with increasing channel length. Our model incorporates customizable noise, such as multi-photon emissions and channel disturbances, directly into the key exchange process, yielding QBER values of ≈4.5% at 20 km and ≈11% at 120 km, consistent with physical systems under the same conditions. Our findings support the development of QKD as a scalable solution for securing the quantum internet and future communication networks.
This study establishes a statistically rigorous and fully reproducible Monte Carlo bench- mark for the BB84 quantum key distribution (QKD) protocol under symmetric depolarizing channel noise. We implement a transparent, parameterized simulator to conduct extensive noise sweeps from p = 0% to p = 26% depolarizing probability. Through large-scale trials, each processing 104 signals with 10 independent repetitions, we generate statistically robust mean Quantum Bit Error Rate (QBER) and Shor-Preskill secure key rates, complete with 95% confidence intervals. Our results validate the fundamental Q p/2 relationship with a maximum deviation from theory of 0.27% and quantify the sharp security threshold collapse. At p = 10% (QBER ≈ 5%), we achieve an ideal asymptotic key rate of RQKD ≈ 0.427 per sifted bit, while the secure fraction becomes negligible beyond p = 22% (QBER ≈ 11%). The empirically determined threshold, where the secure key rate vanishes at pth 0.22, aligns closely with theoretical predictions. This work’s primary contribution is a validated computational framework that serves as an essential benchmark and a computational null hypothesis against which to quantify performance deviations in practical QKD systems aris- ing from reconciliation inefficiency, finite-key effects, and device imperfections, thus bridging a critical gap between asymptotic security theory and the engineering of real-world quantum networks.
As quantum computing threatens classical cryptography like RSA via Shor's algorithm, Quantum Key Distribution (QKD)—especially BB84—offers physics-based security. BB84 leverages quantum principles: Heisenberg Uncertainty, No-Cloning Theorem, and superposition, shifting from math complexity to unbreakable physical laws using polarized photons for key exchange. The protocol detects eavesdropping through Quantum Bit Error Rate (QBER), showing 25% errors in Intercept-Resend attacks. Key challenges like Photon Number Splitting (PNS) attacks are addressed via decoy states. Compared to B92 and E91, BB84 balances feasibility and security best. Despite issues like signal loss, BB84 provides provably secure communication, restoring trust in a post-quantum world.