Machinery & Energetics

Quantum cryptography: Theoretical foundations and practical implementations for the protection of critical infrastructure

Ihor Limar, Yevhen Sevastieiev
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Abstract

The purpose of the article was to theoretically determine harmonised criteria for the applicability of quantum key distribution for the protection of critical infrastructure, taking into account the long-term risk of decryption by adversaries possessing quantum computational resources and traffic archiving capabilities. The methodology relied on a theoretical systems analysis of three Quantum Key Distribution subsystems – sources, detectors, and channels (fibre/free space) – complemented by simplified models of the link budget and bit error probability. A concise scenario analysis was conducted for banking networks, energy systems, and government communications, taking into account scalability, compatibility, and cost. The main results showed that laser intensity stability of 1-2% and higher detector efficiencies – 60-70% for Avalanche Photodiodes and 80-90% for Superconducting Nanowire Single-Photon Detectors – extended practical distances and reduced errors. Without trusted nodes in fibre, 150-200 km was achievable; for urban Free-Space Optics lines, 5-20 km was optimal, while longer distances required network segmentation or satellite segments. Architecturally, it was justified that: for banks – rings with trusted nodes and Free-Space Optics reserve; for energy systems – dual fibre channels “control centre-substation” with a local key cache; for government communications – segmented domains with interagency gateways and satellite redundancy. In all scenarios, a Quantum Key Distribution + Post-Quantum Cryptography hybrid with short key rotation and operational countermeasures against attacks on detectors and channels was appropriate, confirming practical suitability for urban and regional networks. The practical significance lay in providing engineering teams in banking, energy, and government communications with ready-made architectural profiles – from rings and dual fibre channels to segmented domains – with Key Management System/Hardware Security Module integration, definition of Service Level Objective/Service Level Agreement, and phased roadmaps. For regulators and operators, this formed a basis for updating requirements and audits, as well as for planning redundancy (Free-Space Optics/satellite) and Total Cost of Ownership categories

Keywords

key distribution, laser sources, photonic detectors, optical fibre, free-space communication, trusted nodes, banking networks

Suggested citation
Limar, I. , & Sevastieiev, Ye. (2025). Quantum cryptography: Theoretical foundations and practical implementations for the protection of critical infrastructure. Machinery & Energetics, 16(4), 9-20. https://doi.org/10.31548/machinery/4.2025.09
References
  1. Akter, S. (2023). Quantum cryptography for enhanced network security: A comprehensive survey of research, developments, and future directions. Arxiv. doi: 10.48550/arxiv.2306.09248.
  2. Al Hasani, M.H., & Al Naimee, K.A. (2019). Impact security enhancement in chaotic quantum cryptography. Optics & Laser Technology, 119, article number 105575. doi: 10.1016/j.optlastec.2019.105575.
  3. Anilkumar, C., Lenka, S., Neelima, N., & Sathishkumar, V.E. (2024). A secure method of communication through BB84 protocol in quantum key distribution. Scalable Computing Practice and Experience, 25(1), 21-33. doi: 10.12694/scpe.v25i1.2152.
  4. Bavdekar, R., Chopde, E.J., Agrawal, A., Bhatia, A., & Tiwari, K. (2023). Post quantum cryptography: A review of techniques, challenges and standardizations. In 2023 international conference on information networking (pp. 146-151). Bangkok: IEEE. doi: 10.1109/ICOIN56518.2023.10048976.
  5. Berthet, P.-A. (2024). Ciphertext malleability in lattice-based KEMs as a countermeasure to side channel analysis. Arxiv. doi: 10.48550/arXiv.2409.16107.
  6. Brightwood, S., Jarry, H., Frank, E., & Olusegun, J. (2024). Network security and Quantum cryptography: Challenges and opportunities. Retrieved from https://www.researchgate.net/publication/384885336_Network_Security_and_Quantum_Cryptography_Challenges_and_Opportunities.
  7. Chen, C.-L., Zeng, K.-W., Li, W.-Y., Lee, C.-F., Liu, L.-C., & Deng, Y.-Y. (2025). Lightweight post-quantum cryptography: Applications and countermeasures in internet of things, blockchain, and E-learning. Engineering Proceedings, 103(1), article number 14. doi: 10.3390/engproc2025103014.
  8. Dadheech, A. (2021). Post-quantum lattice-based cryptography: A quantum-resistant cryptosystem. In N. Kumar, A. Agrawal, B.K. Chaurasia & R.A. Khan (Eds.), Limitations and future applications of quantum cryptography (pp. 102-123). Hershey: IGI Global Scientific Publishing. doi: 10.4018/978-1-7998-6677-0.ch006.
  9. del Moral, J.O., iOlius, A.D., Vidal, G., Crespo, P.M., & Martinez, J.E. (2024). Cybersecurity in critical infrastructures: A post-quantum cryptography perspective. IEEE Internet of Things Journal, 11(18), 30217-30244. doi: 10.1109/JIOT.2024.3410702.
  10. Dharanish, P., Kokila, S., Mythily, M., & Balachandran, A. (2024). FPGA implementation of post quantum cryptography for high performance. In V. Sharmila, S. Kannadhasan, A.R. Kannan, P. Sivakumar & V. Vennila (Eds.), Challenges in information, communication and computing technology: Proceedings of the 2nd international conference on challenges in information, communication, and computing technology (pp. 209-213). London: CRC Press. doi: 10.1201/9781003559092.
  11. Djordjevic, I.B. (2022). Physical-layer security, quantum key distribution, and post-quantum cryptography. Entropy, 24(7), article number 935. doi: 10.3390/e24070935.
  12. Durr-E-Shahwar, Imran, M., Altamimi, A.B., Khan, W., Hussain, S., & Alsaffar, M. (2024). Quantum cryptography for future networks security: A systematic review. IEEE Access, 12, 180048-180078. doi: 10.1109/ACCESS.2024.3504815.
  13. Faba, J., Brito, J.P., Cresta, J., Pastor, A., López, D., Brito, R., Buruaga, J.S., & Martin, V. (2025). A hybrid approach to address the transition to quantum-resistant cryptography in telecommunication environments. In 2025 international conference on quantum communications, networking, and computing (pp. 122-126). Nara: IEEE. doi: 10.1109/QCNC64685.2025.00027.
  14. Geremew, A., & Mohammad, A. (2024). Preparing Critical infrastructure for post-quantum cryptography: Strategies for transitioning ahead of cryptanalytically relevant quantum computing. International Journal on Engineering Science and Technology, 6(4), 338-365. doi: 10.46328/ijonest.240.
  15. Ghalaii, M., et al. (2023). Satellite-based quantum key distribution in the presence of bypass channels. PRX Quantum, 4, article number 040320. doi: 10.1103/PRXQuantum.4.040320.
  16. Gyongyosi, L., Bacsardi, L., & Imre, S. (2019). A survey on quantum key distribution. Infocommunications Journal, 11(2), 14-21. doi: 10.36244/ICJ.2019.2.2.
  17. Hoschek, M. (2021). Quantum security and 6G critical infrastructure. Serbian Journal of Engineering Management, 6(1), 1-8. doi: 10.5937/SJEM2101001H.
  18. Jude, Q. (2024). Quantum entanglement and the future of secure quantum computing. Retrieved from https://www.researchgate.net/publication/383988027_Quantum_Entanglement_and_the_Future_of_Secure_Quantum_Computing.
  19. Kumar, M., & Mondal, B. (2025). A brief review on quantum key distribution protocols. Multimedia Tools and Applications, 84(27), 33267-33306. doi: 10.1007/s11042-024-20535-x.
  20. Kundu, S., Gupta, T., Sardar, A., Bandyopadhyay, A., Swain, S., & Mallik, S. (2025). A survey on quantum computing: Transforming cryptography, AI/ML, blockchain, and network communication. Franklin Open, 12, article number 100371. doi: 10.1016/j.fraope.2025.100371.
  21. Laule, M.S.C., Silva, J.E.O., & Hanco, H.N. (2024). Lattice-based cryptography: Development and analysis of a new variant of the crystals-kyber algorithm. Interfaces, 20, 165-184. doi: 10.26439/interfases2024.n020.7383.
  22. Li, S., Chen, Y., Chen, L., Liao, J., Kuang, C., Li, K., Liang, W., & Xiong, N. (2023). Post-quantum security: Opportunities and challenges. Sensors, 23(21), article number 8744. doi: 10.3390/s23218744.
  23. Lingaraju, M.P., Kumar, B.T., & Jayachandra, C. (2019). Quantum entanglement and its implications for secure communication. World Journal of Advanced Research and Reviews, 1(1), 82-88. doi: 10.30574/wjarr.2019.1.1.0003.
  24. Liu, Y.-K., & Moody, D. (2024). Post-quantum cryptography and the quantum future of cybersecurity. Physical Review Applied, 21, article number 040501. doi: 10.1103/PhysRevApplied.21.040501.
  25. Nguyen, T.-T., Khac, T.-V., & Quynh, L.-N. (2023). Simulation of the BB84 quantum key exchange protocol. In 2023 15th international conference on knowledge and systems engineering (pp. 1-4). Hanoi: IEEE. doi: 10.1109/KSE59128.2023.10299471.
  26. Pillai, S.V.S., & Polimetla, K. (2024). Analyzing the impact of quantum cryptography on network security. In 2024 international conference on integrated circuits and communication systems (pp. 1-6). Raichur: IEEE. doi: 10.1109/ICICACS60521.2024.10498417.
  27. Pradeep, G., & Nandhini, M.D.S. (2024). Towards efficient quantum cryptography: Enhancing QOTP with entanglement based techniques. Journal of Dynamics and Control, 8(11), 166-183. doi: 10.71058/jodac.v8i11017.
  28. Rahmayanti, D. (2025). Quantum key distribution (QKD) as a wireless telecommunications security solution. Journal of Informatics and Computer Technology, 5(1), 10-26. doi: 10.55606/jitek.v5i1.5765.
  29. Rajpoot, S., Singh, K., Singh, C.P., & Sharma, B.K. (2023). Security challenges and future research in quantum key distribution networks. In 2023 10th IEEE uttar pradesh section international conference on electrical, electronics and computer engineering (pp. 95-100). Gautam Buddha Nagar: IEEE. doi: 10.1109/UPCON59197.2023.10434510.
  30. Rayhan, A., Bushra, Z.I., Chowdhury, S., Faruqui, N., & Barua, B. (2025). Performance analysis of free space optical communication in urban rain environment. In 2025 international conference on electrical, computer and communication engineering (pp. 1-6). Chittagong: IEEE. doi: 10.1109/ECCE64574.2025.11013976.
  31. Reddy, D.V., Nerem, R.R., Nam, S.W., Mirin, R.P., & Verma, V.B. (2020). Superconducting nanowire single-photon detectors with 98% system detection efficiency at 1550 nm. Optica, 7(12), 1649-1653. doi: 10.1364/OPTICA.400751.
  32. Shao, Y., Wang, H., Pi, Y., Huang, W., Li, Y., Liu, J., Yang, J., Zhang, Y., & Xu, B. (2021). Phase noise model for continuous-variable quantum key distribution using a local local localoscillator. Physical Review A, 104, article number 032608. doi: 10.1103/PhysRevA.104.032608.
  33. Shunza, J. (2019). Lattice-based cryptosystems and post-quantum cryptography. Kigali: African Institute for Mathematical Sciences. doi: 10.13140/RG.2.2.18756.50563.
  34. Singh, S., Jha, C.K., Bende, A., Rana, V., Patkar, S., Drechsler, R., & Merchant, F. (2024). MemSPICE: Automated simulation and energy estimation framework for MAGIC-based logic-in-memory. In Proceedings of the 29th Asia and south pacific design automation conference (pp. 282-287). Incheon: IEEE. doi: 10.1109/ASP-DAC58780.2024.10473924.
  35. Sreerangapuri, A. (2024). Post-quantum cryptography for ai-driven cloud security solutions. International Journal for Multidisciplinary Research, 6(5). doi: 10.36948/ijfmr.2024.v06i05.29032.
  36. Stanley, M., Gui, Y., Unnikrishnan, D., Hall, S.R.G., & Fatadin, I. (2022). Recent progress in quantum key distribution network deployments and standards. Journal of Physics Conference Series, 2416, article number 012001. doi: 10.1088/1742-6596/2416/1/012001.
  37. Stelzer, T., Oberhansl, F., Schupp, J., Karl, P., & Turcuman, H. (2025). Extended version: Enabling lattice-based post-quantum cryptography on the opentitan platform. Journal of Cryptographic Engineering, 15, article number 11. doi: 10.1007/s13389-025-00369-5.
  38. Ukwuoma, H.C., Arome, G., Thompson, A., & Alese, B.K. (2022). Post-quantum cryptography-driven security framework for cloud computing. Open Computer Science, 12(1), 142-153. doi: 10.1515/comp-2022-0235.
  39. Yu, C., Xu, Q., & Zhang, J. (2024). Recent advances in InGaAs/InP single-photon detectors. Measurement Science and Technology, 35(12), article number 122003. doi: 10.1088/1361-6501/ad76ca.