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

TL;DR

This paper evaluates a hybrid key exchange protocol combining public-key cryptography with physical-layer security to counteract quantum threats, aiming to provide short-term secrecy and delay quantum attacks.

Contribution

It introduces a novel hybrid protocol that leverages physical-layer security alongside public-key schemes to enhance security against quantum adversaries.

Findings

The protocol can delay quantum attacks, providing a window for secure communication.

Physical-layer jamming enhances the security of key exchange.

The paper discusses security challenges and future research directions.

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, evaluate a key exchange protocol based on combining public-key schemes with physical-layer security, anticipating the prospect of quantum attacks. If powerful quantum attackers cannot immediately obtain private keys, 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.