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arXiv:2412.13352 · Conference on Information Sciences and Systems

Key Exchange in the Quantum Era: Evaluating a Hybrid System of Public-Key Cryptography and Physical-Layer Security

Paul Staat, Meik Dörpinghaus, Azadeh Sheikholeslami, Christof Paar, Gerhard Fcllwcis, Dennis Goeckel

Published Mar 19, 2025• 1 citation
arXivHTMLPDF

Abstract

Today's information society relies on cryptography to achieve security goals such as confidentiality, integrity, authentication, and non-repudiation for digital communications. Here, public-key cryptosystems play a pivotal role to share encryption keys and create digital signatures. However, quantum computers threaten the security of traditional public-key cryptosystems as they can tame computational problems underlying the schemes, i.e., discrete logarithm and integer factorization. The prospective arrival of capable-enough quantum computers already threatens today's secret communication in terms of their long-term secrecy when stored to be later decrypted. Therefore, researchers strive to develop and deploy alternative schemes.In this work, we evaluate a key exchange protocol based on combining public-key schemes with physical-layer security, anticipating the prospect of quantum attacks: If a powerful quantum attacker cannot immediately obtain a private key, legitimate parties have a window of short-term secrecy to perform a physical-layer jamming key exchange (JKE) to establish a long-term shared secret. Thereby, the protocol constraints the computation time available to the attacker to break the employed public-key cryptography. In this paper, we outline the protocol, discuss its security, and point out challenges to be resolved.

DOI
10.1109/ciss64860.2025.10944740

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Quantum computing poses a growing challenge to conventional public-key cryptographic systems, particularly those relying on integer factorization and discrete logarithm problems. Widely deployed schemes such as RSA and elliptic curve cryptography are expected to become vulnerable as large-scale quantum computing capabilities emerge. This concern has intensified the demand for communication frameworks capable of maintaining long-term confidentiality in the presence of both classical and quantum-enabled adversaries. This paper presents a Hybrid Quantum-Resilient Key Exchange Algorithm (HKEA) that combines classical cryptographic mechanisms with lattice-based post-quantum cryptographic techniques to establish secure session keys. The proposed framework employs a dual-layer key establishment process in which classical and post-quantum shared secrets are integrated to generate a strengthened hybrid session key. The design aims to preserve compatibility with existing communication infrastructures while improving resistance to future quantum attacks and mitigating risks associated with Harvest-Now-Decrypt-Later (HNDL) threats. A prototype implementation was developed using Python-based cryptographic and post-quantum security libraries. The framework was evaluated using key generation time, latency, throughput, computational overhead, and security strength as performance indicators. Comparative analysis against conventional cryptographic approaches indicates that the proposed HKEA provides enhanced quantum resilience with only a modest increase in computational cost. The proposed approach offers a practical pathway toward secure and scalable communication systems for next-generation quantum-era network environments.
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