With the rapid advancement of quantum technologies, quantum key distribution (QKD) has become a key approach to secure communication. This study presents a software-only implementation of the BB84 QKD protocol developed in Python using IBM’s Qiskit Aer simulator. The proposed framework is designed for educational and prototyping purposes rather than for hardware-level security evaluation. The simulator models the core stages of BB84: random bit/basis generation, state preparation, basis-dependent measurement, sifting, and parameter estimation via QBER, followed by conceptual post-processing. Evaluation reports (i) the expected sifted-key ratio under random basis selection, (ii) the ideal-channel QBER behavior under noise-free Aer execution, and (iii) the theoretical intercept–resend detection probability derived from standard BB84 analysis. For sequences of ≥100 bits, the implementation matches standard BB84 expectations under ideal Aer execution: an expected sifted-key ratio of ≈50%, QBER → 0 in the absence of adversarial interference, and an intercept–resend detection probability above 99.9% for m = 100 disclosed verification bits. These results demonstrate that an idealized virtual environment can reproduce the BB84 measurement–disturbance trade-off in the information-theoretic sense, without claiming physical decoherence modeling unless an explicit Aer noise model is enabled. The analysis focuses on idealized BB84 behavior, where disturbance arises solely from basis mismatch and intercept– resend measurements rather than from physical decoherence or hardware noise models. The framework provides a reproducible platform for teaching and early-stage experimentation, with future work targeting realistic noise models and advanced post-processing.
With the rapid advancement of quantum technologies, quantum key distribution (QKD) has become a key approach to secure communication. This study presents a software-only implementation of the BB84 QKD protocol developed in Python using IBM’s Qiskit Aer simulator. The proposed framework is designed for educational and prototyping purposes rather than for hardware-level security evaluation. The simulator models the core stages of BB84: random bit/basis generation, state preparation, basis-dependent measurement, sifting, and parameter estimation via QBER, followed by conceptual post-processing. Evaluation reports (i) the expected sifted-key ratio under random basis selection, (ii) the ideal-channel QBER behavior under noise-free Aer execution, and (iii) the theoretical intercept–resend detection probability derived from standard BB84 analysis. For sequences of ≥100 bits, the implementation matches standard BB84 expectations under ideal Aer execution: an expected sifted-key ratio of ≈50%, QBER → 0 in the absence of adversarial interference, and an intercept–resend detection probability above 99.9% for m = 100 disclosed verification bits. These results demonstrate that an idealized virtual environment can reproduce the BB84 measurement–disturbance trade-off in the information-theoretic sense, without claiming physical decoherence modeling unless an explicit Aer noise model is enabled. The analysis focuses on idealized BB84 behavior, where disturbance arises solely from basis mismatch and intercept– resend measurements rather than from physical decoherence or hardware noise models. The framework provides a reproducible platform for teaching and early-stage experimentation, with future work targeting realistic noise models and advanced post-processing.
The rapid progress of quantum computing demands secure communication protocols which are beyond classical cryptographic techniques. This necessity of Quantum Key Distribution (QKD) is met by providing security relying on the fundamental laws of quantum mechanics. In the work presented, the BB84 protocol is implemented using Qiskit platform provided by IBM. The performance is analyzed for both the ideal channel conditions and an intercept–resend eavesdropping scenario studying its security behavior and performance. 100% key agreement is observed with a QBER of 0% for the BB84 protocol executed under the ideal condition. When an eavesdropper is introduced, the QBER increases significantly, ranging from 16% to 38%, exceeding the acceptable security threshold of 11% and resulting in complete rejection of the generated key. Performance analysis carried out for key sizes between 100 and 1000 qubits shows that the execution time follows O(n) trend growing linearly. This simulation validates the correct operation of the BB84 protocol and demonstrates a detailed performance and security analysis of a QKD system using IBM Qiskit.
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.
The rapid advancement of quantum computing poses a significant threat to classical cryptographic systems that form the backbone of modern digital security.Algorithms such as RSA and ECC, which rely on the computational difficulty of integer factorization and discrete logarithm problems, become vulnerable to quantum attacks, particularly Shor's algorithm.This project presents a comprehensive Quantum Key Distribution (QKD) Simulator that implements the BB84 and E91 protocols using IBM's Qiskit quantum computing framework, providing an interactive platform for understanding, simulating, and analyzing quantum-safe key exchange mechanisms.The simulator features a full-stack architecture with a FastAPI backend powered by Python and Qiskit for quantum circuit execution, and a React 19 frontend with TypeScript for interactive visualization.The BB84 protocol implementation supports configurable qubit counts, multiple measurement bases (Z, X, and Diagonal), Eve's intercept-resend attack simulation with adjustable interception rates, and Quantum Bit Error Rate (QBER) calculation with a security threshold of 8.5%.The E91 protocol implementation uses entangled Bell state pairs with configurable measurement angles, CHSH inequality violation testing for quantum security verification, and reverse gate anti-eavesdropping mechanisms.Additionally, the system includes an AES encryption module that uses quantum-generated keys from BB84 and E91 simulations to perform AES-128, AES-192, and AES-256 encryption, with privacy amplification for keys shorter than the required length.A simulation history system with SQLite and PostgreSQL support enables experiment tracking, comparison, and analysis.The project demonstrates the practical application of quantum mechanics principles to cryptographic security and serves as an educational tool for understanding the transition from classical to quantum-safe cryptography.
Quantum Key Distribution (QKD) provides a novel alternative to Classical Key Distribution in protecting secure communications, but poses challenges in terms of research and widespread adoption. While the resource-intensive nature of QKD setups limit 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 is 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. Our model incorporates customizable noise, such as multi-photon emissions and channel disturbances, directly into the key exchange process, allowing for an approach that utilizes simulated fiber optics and theoretical noise models to replicate physical conditions. Our findings support the development of QKD as a scalable solution for securing the quantum internet and future communication networks.
Quantum Key Distribution (QKD) offers information- theoretically secure key establishment grounded in the laws of quantum physics, yet its practical reach is limited by the prohibitive cost of photonic hardware and the fragmented nature of existing simulation tools. Most simulators support only a single protocol and report results from individual stochastic runs, making systematic protocol comparison and reproducible statistical inference difficult. This paper presents a unified QKD simulation platform that implements four foundational protocols BB84, B92, E91, and BBM92 within a single Python/Qiskit engine. A shared impairment model covers fiber attenuation, source and detector losses, po- larization drift, and configurable intercept-resend eavesdropping. The platform is accessible through two independent interfaces that share the same backend: a desktop application (Tkinter, Matplotlib) for local experimentation and a browser-based web client (React, Node.js/Express) for zero-install remote access. All reported results are drawn from repeated-run studies (20 independent runs, 10000 qubits each), with mean, standard deviation, and 95% confidence intervals stated throughout. At a 25 km fiber link, BB84 achieves the highest mean key-rate of 160,045 Hz, followed by BBM92 (80023 Hz), E91 (52815 Hz), and B92 (40011 Hz) ordering that tracks simulation-derived sifting efficiencies precisely. Under the E91 protocol, the CHSH S-statistic averages 2.12 at baseline and falls to 1.58 when an eavesdropper is activated, demonstrating Bell-inequality-based intrusion detection independent of QBER