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Sensors

Scenarios for Optical Encryption Using Quantum Keys

Luis Velasco, Morteza Ahmadian, Laura Ortíz, Juan P. Brito, Antonio Pastor, Jose M. Rivas, Sima Barzegar, Jaume Comellas, Vicente Martín, Marc Ruiz

Published Oct 15, 2024• 4 citations
Publisher

Abstract

Optical communications providing huge capacity and low latency remain vulnerable to a range of attacks. In consequence, encryption at the optical layer is needed to ensure secure data transmission. In our previous work, we proposed LightPath SECurity (LPSec), a secure cryptographic solution for optical transmission that leverages stream ciphers and Diffie-Hellman (DH) key exchange for high-speed optical encryption. Still, LPSec faces limitations related to key generation and key distribution. To address these limitations, in this paper, we rely on Quantum Random Number Generators (QRNG) and Quantum Key Distribution (QKD) networks. Specifically, we focus on three meaningful scenarios: In Scenario A, the two optical transponders (Tp) involved in the optical transmission are within the security perimeter of the QKD network. In Scenario B, only one Tp is within the QKD network, so keys are retrieved from a QRNG and distributed using LPSec. Finally, Scenario C extends Scenario B by employing Post-Quantum Cryptography (PQC) by implementing a Key Encapsulation Mechanism (KEM) to secure key exchanges. The scenarios are analyzed based on their security, efficiency, and applicability, demonstrating the potential of quantum-enhanced LPSec to provide secure, low-latency encryption for current optical communications. The experimental assessment, conducted on the Madrid Quantum Infrastructure, validates the feasibility of the proposed solutions.

DOI
10.3390/s24206631

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Optical communications providing huge capacity and low latency remain vulnerable to a range of attacks. In consequence, encryption at the optical layer is needed to ensure secure data transmission. In our previous work, we proposed LightPath SECurity (LPSec), a secure cryptographic solution for optical transmission that leverages stream ciphers and Diffie-Hellman (DH) key exchange for high-speed optical encryption. Still, LPSec faces limitations related to key generation and key distribution. To address these limitations, in this paper, we rely on Quantum Random Number Generators (QRNG) and Quantum Key Distribution (QKD) networks. Specifically, we focus on three meaningful scenarios: In Scenario A, the two optical transponders (Tp) involved in the optical transmission are within the security perimeter of the QKD network. In Scenario B, only one Tp is within the QKD network, so keys are retrieved from a QRNG and distributed using LPSec. Finally, Scenario C extends Scenario B by employing Post-Quantum Cryptography (PQC) by implementing a Key Encapsulation Mechanism (KEM) to secure key exchanges. The scenarios are analyzed based on their security, efficiency, and applicability, demonstrating the potential of quantum-enhanced LPSec to provide secure, low-latency encryption for current optical communications. The experimental assessment, conducted on the Madrid Quantum Infrastructure, validates the feasibility of the proposed solutions.
Optical communications have enabled high-speed data transmission over long distances. However, data are transmitted plain unless are encrypted on higher layers, e.g., IP and TCP, precisely because of: i) the high data rates; and ii) the need of secure key exchange between the end-points of the optical connection. Meanwhile, quantum enabled cryptography has emerged as a promising solution for securing communications by leveraging the principles of quantum mechanics which provides unlimited and unconditional security. Although Quantum Key Distribution (QKD) protocols can deliver quantum keys to distant end-points, there are scenarios where one of them is not within the security perimeter of the quantum network. This demonstration focuses on the intersection of optical communication and quantum security, highlighting the synergies between these two domains and their potential to ensure secure communication networks. We explore the integration of optical communication with quantum technologies and showcase how optical encryption using quantum keys retrieved from QKD and Quantum Random Number Generator (QRNG) systems is performed. Retrieved keys are expanded to the required rate and then used to encrypt the input data at line speed.
Securing optical communication networks against evolving cyber threats necessitates advanced cryptographic techniques. Quantum cryptography offers an unbreakable security framework, leveraging the principles of quantum mechanics. However, integrating quantum cryptography with lightweight and efficient stream ciphers remains a challenge in high-speed optical networks. Traditional encryption methods, such as AES and RSA, struggle to meet the real-time demands of optical communication due to computational overhead and vulnerability to quantum attacks. This study introduces a hybrid security framework incorporating Quantum Key Distribution (QKD) with Espresso ciphers and the Grain stream cipher to enhance security and efficiency in optical networks. The Espresso cipher, known for its ultra-lightweight design and energy efficiency, ensures minimal computational complexity, while the Grain stream cipher provides robust resistance against differential and linear cryptanalysis. The integration with QKD ensures unconditional security through quantum properties such as no-cloning and Heisenberg’s uncertainty principle. Performance evaluation was conducted using a 100 Gbps optical network, demonstrating a significant reduction in encryption latency by 37% compared to conventional AES-based encryption. The proposed framework also achieved an 89.6% improvement in key generation efficiency and reduced computational overhead by 41.3%. Furthermore, resistance against brute-force and side-channel attacks was significantly enhanced, providing a secure and efficient cryptographic solution for high-speed optical networks.
The increasing reliance on optical communication networks for high-speed data transmission has amplified concerns regarding secure information exchange in the era of quantum computing. Classical cryptographic protocols such as RSA and ECC, though widely deployed, are vulnerable to attacks from large-scale quantum computers executing Shor’s algorithm. Quantum Key Distribution (QKD) has emerged as a revolutionary cryptographic paradigm that leverages the principles of quantum mechanics to enable theoretically unbreakable key exchange. This paper investigates the integration of QKD into optical communication networks, focusing on protocol design, implementation challenges, and potential scalability. Through scenario-based evaluation, the study highlights the trade-offs between quantum security and practical deployment constraints such as channel loss, photon detector efficiency, and key generation rates. Results from simulated models demonstrate that while QKD can achieve provable security in metropolitan-area networks, long-distance transmission requires advanced techniques such as quantum repeaters and trusted nodes. This work concludes that QKD offers a promising pathway toward quantum-safe communication but necessitates
Quantum Noise Stream Cipher (QNSC) has emerged as a physical-layer encryption technique that exploits quantum noise and non-orthogonal coherent-state modulation to secure optical communication. However, the security of QNSC relies exceedingly on the secrecy and freshness of its seed key. Quantum Key Distribution (QKD), on the other hand, provides information-theoretically secure key exchange rooted in the laws of quantum mechanics. The convergence of these two paradigms, i.e., integrated QKD-QNSC architectures, offers a compelling solution to each of their limitations. In such integrated systems, QKD continuously supplies and refreshes the secret seed key that governs QNSC modulation. Thus, governing a unified security framework that couples provably secure key establishment with high-speed quantum-enhanced physical-layer encryption. This work presents a comprehensive review of QNSC systems, examining their operating principles, security models under various attacks, and their integration with QKD systems. We analyze the security interplay between the key generation and encryption layers and survey experimental demonstrations and architectural progress toward practical deployment. Furthermore, we identify the open challenges and future research directions that must be addressed to realize fully integrated, quantum-secured optical communication networks at a practical scale.
The increasing reliance on optical communication networks for high-speed data transmission has amplified concerns regarding secure information exchange in the era of quantum computing. Classical cryptographic protocols such as RSA and ECC, though widely deployed, are vulnerable to attacks from large-scale quantum computers executing Shor�s algorithm. Quantum Key Distribution (QKD) has emerged as a revolutionary cryptographic paradigm that leverages the principles of quantum mechanics to enable theoretically unbreakable key exchange. This paper investigates the integration of QKD into optical communication networks, focusing on protocol design, implementation challenges, and potential scalability. Through scenario-based evaluation, the study highlights the trade-offs between quantum security and practical deployment constraints such as channel loss, photon detector efficiency, and key generation rates. Results from simulated models demonstrate that while QKD can achieve provable security in metropolitan-area networks, long-distance transmission requires advanced techniques such as quantum repeaters and trusted nodes. This work concludes that QKD offers a promising pathway toward quantum-safe communication but necessitates advancements in hardware, standardization, and hybrid cryptographic strategies for widespread adoption.
Quantum Key Distribution (QKD) provides information-theoretic security based on quantum mechanics, but its practical deployment is limited by its reliance on classical infrastructure and inability to operate as a standalone solution.Recent research emphasizes hybrid approaches that combine QKD with post-quantum cryptography (PQC) to achieve practical and robust security.This paper presents a hybrid key distribution model integrating QKD with the postquantum key encapsulation mechanism.The two independently generated keys are combined to derive a unified shared secret, enhancing resilience against both classical and quantum adversaries.The system is implemented using a simulated quantum environment, enabling the emulation of quantum communication over classical networks.The proposed approach is validated through a secure image transmission use case, demonstrating the correctness of the hybrid key exchange.The results highlight the feasibility of hybrid classical-quantum cryptographic systems as a practical step toward secure communication in emerging quantum network infrastructures.