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.
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.
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.
Abstract Secure military communications depend on the confidentiality of exchanged cryptographic keys across command centers, satellite links, and classified order transmission. Classical key-distribution protocols rely on computational hardness assumptions that provide no intrinsic mechanism for detecting interception; an adversary who copies transmitted ciphertext leaves no physical trace. Quantum Key Distribution (QKD), and specifically the BB84 protocol, replaces this assumption with a physical guarantee derived from quantum mechanics: any attempt to measure an unknown quantum state necessarily disturbs it, rendering interception statistically detectable. This study implements the BB84 protocol at the circuit level — qubit state preparation, basis selection, interception modeling, and measurement — and validates its central security property, the Quantum Bit Error Rate (QBER) signature of eavesdropping, in two stages: (1) a noiseless statevector simulation using the PKTron quantum computing framework over ten independent trials per condition, and (2) hardware execution on IBM Quantum's ibm_fez superconducting processor. In simulation, the average QBER without an eavesdropper was 0.000, and with a full intercept-resend attack was 0.248, closely matching the theoretical prediction of 0.25. On real hardware, the undisturbed channel returned QBER = 0.000 (19 sifted bits) and the eavesdropped channel returned QBER = 0.261 (23 sifted bits), in close agreement with both theory and the simulated baseline. These results provide a reproducible, two-platform validation of the eavesdropper-detection mechanism that underlies the security claims made for QKD-protected communications. This study validates the cryptographic detection primitive only; it does not constitute a deployed secure communications system, and extending these results to operational command, satellite, or classified-order channels requires physical single-photon transmission hardware, authenticated classical channels, and full key-management infrastructure outside the scope of this work.
The BB84 protocol is fundamental to quantum-secure communications, yet its extension to multi-receiver networks remains underexplored. This study addresses this gap by implementing a dual-receiver BB84 framework in Qiskit to evaluate security against intercept–resend and photon-number-splitting (PNS) attacks. Our methodology incorporates weak coherent pulses and realistic channel imperfections. Key findings show that intercept–resend attacks induce a detectable (~25%) increase in QBER, while PNS attacks allow a 100% gain in eavesdropper information with less than 2.5% QBER—revealing a critical vulnerability, which highlights the importance of a true single-photon source. The findings emphasize the suitability of BB84 for multiparty QKD scenarios, either as a decoy-state mechanism for enhanced eavesdropping detection or as a direct secure communication protocol.
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.
Quantum computing poses significant threats to conventional cryptographic techniques such as RSA and AES, motivating the need for quantum secure communication methods. Quantum Key Distribution (QKD) offers information theoretic security based on fundamental quantum principles. This paper presents a simulation-based analysis of well-known QKD protocols, namely BB84, B92, and E91, using the IBM Qiskit framework. Realistic quantum channel effects, including noise, decoherence, and eavesdropping, are modeled to evaluate protocol performance. Key metrics such as error rate, secret key generation, and security characteristics are analyzed and compared. The study highlights practical challenges in QKD implementation, including hardware limitations and channel losses, and discusses insights toward scalable and robust quantum communication systems. The results support the feasibility of QKD as a promising solution for secure communication in the quantum era.
Quantum communication leverages the principles of quantum mechanics, such as superposition and entanglement, for inherently secure data transmission that can detect any eavesdropping attempt. This research addresses the limitations of classical encryption by proposing a hybrid Quantum Key Distribution (QKD) protocol that integrates the Bennett & Brassard 1984 Protocol(BB84) and Scarani-Acín-Ribordy-Gisin 2004 Protocol(SARG04) protocols. The primary objective is to enhance resilience against advanced threats such as Photon Number Splitting (PNS) and collective attacks, which are significant vulnerabilities in standard QKD implementations. The quantum channel is modeled using Qiskit Aer's noise framework, incorporating fiber attenuation (0.1−0.25dB/km), depolarization (1−5%), and detector dark counts (0.01−0.03probability), varied across 10 rounds. A simulation spanning 10 rounds evaluated key metrics, including Quantum Bit Error Rate (QBER), photon loss, and final key entropy. The results demonstrate the protocol's robustness, achieving a 0 % QBER in 50 % of the trials, representing a significant improvement in secure key generation. The average QBER across all rounds was 12.5 %, which is well below the 11 % theoretical threshold for secure communication. The highest QBER recorded was5 0 %in Round 02, where high depolarization and an eavesdropping attempt were simulated. The work's findings indicate that the hybrid BB84-SARG04 protocol significantly enhances the security and reliability of quantum communication.