A group of researchers have developed an algorithm designed to prevent threat actors from disrupting quantum communication channels across an entire network.

Researchers from Italy's Politecnico di Milano and the University of Waterloo in Canada teamed up to develop a scalable heuristic algorithm capable of solving the routing and wavelength assignment problem.

In quantum key distribution (QKD) networks, a key challenge is routing traffic and assigning wavelengths to communication channels. Attackers can exploit this by using high-power jamming signals on a single link to disrupt multiple communication paths across the network.

Detailed in a recently published paper, the researchers' algorithm, dubbed Min-maxNAR, prevents attackers from using such jamming signals and subsequently makes what is meant to be ultra-secure communication systems even more secure.

Tests of the algorithm in action reduced the impact of simulated jamming attacks by 27%, with the researchers writing, “simulation results confirm that our method significantly outperforms the baseline in terms of security and scalability.”

The breakthrough addresses a critical vulnerability that has made security agencies like the NSA skeptical about quantum networks' real-world viability.

In guidance published back in 2020, the NSA said QKD systems, which promise unhackable communication using quantum physics principles, “suffer from limitations and implementation challenges that make it impractical for use in National Security System (NSS) operational networks.”

The researchers are seeking to address these concerns and make QKD viable by introducing a new metric called "maximum number of affected requests" (maxNAR) to measure worst-case attack impact, then optimizing how data routes through the network to minimize this vulnerability.

The researchers tested their approach on both small-scale laboratory networks and larger 14-node configurations, consistently showing significant improvements over traditional routing methods.

In their attempt to bolster the technology, the researchers suggested their algorithm marked the first systematic approach to address the "attack radius" problem in quantum networks.

"To our knowledge, this is the first work to model and optimize maxNAR for improving QKD network resilience," the team wrote, suggesting their algorithm could help quantum communication systems overcome a key barrier to widespread adoption in critical infrastructure.

QKD is slowly transitioning from experimental systems to eventual real-world deployments.

Cisco announced back in 2022 that it’s looking into applying QKD to support networks for data centers, IoT, autonomous systems, and 6G. Carriers are also getting involved, with Verizon and SK Telecom having previously tested quantum cryptography communication networks.