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
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
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.
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.
Quantum Key Distribution (QKD) provides physical-layer security based on quantum state disturbance rather than computational complexity. However, operational viability depends heavily on physical channel parameters, optical loss, finite-key statistical bounds, and network key-sharing constraints. This paper presents a multi-metric, quantitative evaluation of a three-intensity decoy-state BB84 QKD link and its application within a time-shared star network. Using a Monte Carlo sampling framework (n=60 replications per configuration), we evaluate link distance (0–200 km), attenuation (0.18-0.30 dB/km), detector efficiency (10-40%), dark count probability (10-8-10-5 per gate), eavesdropping intensity (0-50%), privacy-amplification block size (106-109 pulses), and simultaneous user pair load (1-20 pairs). Under baseline settings (0.20 dB/km, 25% detector efficiency, 500 MHz pulse rate, signal intensity μ=0.50, 1.5% misalignment, block size N=5×107), the secure key rate (SKR) drops from 12.83 Mbit/s at 0 km to 295.63 kbit/s at 80 km, reaching non-positive values at 200 km due to finite statistical penalties. Intercept-resend attacks degrade secrecy, suppressing output to zero at ∼20% interception intensity (QBER=6.51%). In the shared network, a target demand of 20 kbit/s per user pair experiences depletion when active pairs exceed 12, despite a positive aggregate link generation rate. The findings demonstrate that QKD viability requires joint evaluation of SKR, QBER, finite-key confidence, latency, and multi-user key supply dynamics.
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) represents a paradigm shift in cryptographic security, offering information-theoretic confidentiality based on fundamental principles of quantum mechanics rather than computational hardness assumptions. The emergence of advanced quantum processors with ever-increasing qubit counts has accelerated the timeline for cryptographically-relevant quantum computers, necessitating immediate migration to quantum-safe communication protocols. This paper introduces a comprehensive QKD-based network integrity mechanism implemented as a Flask-based web chatting application that provides end-to-end security with real-time attack detection and automated mitigation. The system integrates a complete BB84 protocol simulation with polarized photon transmission modeling, incorporating realistic quantum channel parameters including attenuation (0.2 dB/km), dark count probability (10⁻⁶), and detector efficiency (30%). The architecture comprises four integrated modules: Quantum Key Distribution Engine implementing the full BB84 protocol stack with adaptive basis selection and error reconciliation; Secure Chat Interface supporting multi-user rooms, private messaging, and file sharing with one-time pad encryption using quantum-generated keys refreshed at optimal intervals; Network Integrity Monitor employing statistical analysis and machine learning techniques to detect eavesdropping attempts through quantum bit error rate (QBER) analysis, timing anomalies, and photon statistics; Automated Mitigation System that quarantines detected attackers through session termination, IP blacklisting, key revocation, and emergency key regeneration. Experimental evaluation demonstrates detection rates of 99.7% for intercept-resend attacks at 24.8% QBER, 98.2% for photon number splitting attacks at 15.3% QBER, and 99.1% for man-in-the-middle attacks at 18.7% QBER. The system achieves key generation rates of 1.82 kbps over 10 km simulated fiber, with 1.8-second quarantine response time meeting stringent incident response requirements. Scalability testing confirms support for 5,000+ concurrent users with 320 ms response time, making the solution suitable for production deployment. This work represents the first production-ready integration of quantum key distribution with a complete web chat application featuring automated attack detection and mitigation, bridging the gap between theoretical quantum cryptography and practical secure communication tools.
Quantum Key Distribution (QKD) which is the name of cryptography in quantum environment act as the highest developed area in quantum communication and computing technology (QCIT). \n \nQKD is inventive technology which utilize the laws of quantum to create a cryptographic share key to make the communication system secure. The unique feature of QKD assures eavesdropping detectable during quantum communications which is fascinating for a high-level secure environment.Most of the traditional cryptographic methods which we use currently are based on mathematical scheme or Computational complexity theory which are not completely safe. Using quantum cryptography has been achieved extensive steps in communication security establishment. As the information Unit has been changed from “bit” to Quantum bit (Qubit), a new element has been offered that can guarantee the shared information confidentiality between parties. The confidentiality of system is established via exchanging a secret key through a channel of quantum, the key which we use for encrypting the shared data. This structure has quantum integration which has been developed by physics law and techniques of cryptography. \n \nThis thesis has proposed a modified version of QKD protocol, this new protocol will generate a cryptographic share key for a more efficient, lower cost and secure communication between two parties (sender and Receiver). This new protocol principal is similar to BBM92, but the source of photon moved to sender instead of third-party photon generator, following steps will be executed in this Experiment: \n \n•\tObserve different categories protocols of QKD in details \n•\tThe Quantum Mechanics Visualisation Project (QuVis) is the simulation software that has been used for implementing the proposed protocol [BB84 with spin] among the other three (BBM92, B92 and BB84). \n•\tProbability ratio of error will be tested and compared for all protocols, for this experiment 100 to 5000 photons will be sent. \n \nBy Analysing collected data in this experiment, it will be determined which one of this four protocols lead the detecting of eavesdropping. Simulation software accomplishes the value of error key probability which receiver can use and should not pass over the range limit of 0.25 & 0.5.