Toshiba Warns of Quantum Threats to Telecom Networks

Telecommunications networks support modern society. They carry everything from consumer identities and enterprise transactions to critical-infrastructure telemetry and control planes for national services. Securing these networks is essential not only for the trust of customers but also to safeguard the immense volumes of data transmitted daily.

Yet an urgent vulnerability is emerging. As 2025 marks the International Year of Quantum and the centenary of quantum mechanics, quantum technology is poised to disrupt the foundations of digital security.

Quantum computing is no longer confined to research laboratories – powerful machines are on the horizon that could break the encryption methods protecting today’s networks.

Andrew Shields, Vice President and General Manager of Quantum Technology at Toshiba Europe, warns: “Telecoms providers face a critical choice: to lead the quantum transition now or risk being left behind.”

Q-Day is not the deadline

Speculation abounds over when “Q-Day” – the moment a quantum computer can effectively break conventional security – will arrive. Andrew explains:

“When Q-Day comes, a 2048-bit RSA key that would take today’s most powerful classical supercomputer over 100 million years to crack could be decoded by a large quantum computer in mere hours," says Andrew. 

But Andrew stresses that waiting until that point is a dangerous strategy. He notes that adversaries already harvest encrypted traffic through 'store-now-decrypt-later' attacks, planning to decrypt it once quantum computers become readily available.

Financial transactions, government communications, healthcare records and critical infrastructure remain particularly exposed because of their long shelf lives. Andrew argues that delaying until Q-Day compresses necessary changes into a rushed rollout, at which point it will be too late.

Defence-in-depth for the Quantum Era

The key to a successful transition is adopting a hybrid defence-in-depth strategy. Quantum-safe networks are already commercially deployable and provide an immediate opportunity for operators.

Andrew notes: “The strongest defence in the quantum era comes from a hybrid approach, pairing both Quantum Key Distribution (QKD), a physics-based method for distributing encryption keys that can detect when data has been intercepted with Post-Quantum Cryptography (PQC), a new software-based algorithm standardised by NIST that resists quantum attacks through mathematical complexity.”

Andrew explains the benefits: “For an attacker to gain access to these systems they would simultaneously need to break both QKD and PQC, so combining them creates defence-in-depth.”

The technologies operate today. For example, Orange Business and Toshiba recently launched Orange Quantum Defender, France’s first commercial quantum-safe network service.

The deployment combines QKD and PQC on Orange’s metro fibre infrastructure with a leading French financial services firm already connecting multiple sites. Similar networks operate in London, Tokyo, Singapore and North America.

Scaling Quantum Networks

Operators further benefit from the scalability of quantum networks. Initial deployments allow operators to test use cases and develop internal expertise, which can then expand as Q-Day approaches.

Andrew observes: “Quantum optics are not inherently more expensive than classical systems and the potential cost of not deploying them far outweighs initial investments, especially as the global average cost of a data breach stands at US$4.4 million in 2025.”

Failure to act can erode customer trust, jeopardise enterprise contracts that require quantum-safe roadmaps and disrupt 5G core network operations. Conversely, demonstrating defence-in-depth and crypto-agility strengthens customer confidence and provides a competitive advantage.

Metro-scale deployments of Twin-Field QKD already support links up to 150 kilometres with potential to extend to 250 kilometres using advanced detectors.

Over time, quantum repeaters will enable transoceanic links while satellite-based QKD will offer global coverage, including remote areas where fibre is unavailable.

Andrew highlights that operators can act now and enable their quantum-safe networks to grow with them in distance, scale and sophistication.

The Quantum era starts now

Telecom providers are uniquely positioned to lead in the post-quantum era.

Andrew highlights the immediate task: “Protecting today’s traffic against tomorrow’s adversaries through defence-in-depth, combining QKD’s physics-based, eavesdropping-detectable keying with PQC’s software-based, standardised cryptography.”

Early adopters who deploy metro networks, implement crypto-agility and run pragmatic pilots will influence standards, shape ecosystems and capture revenue in the quantum era.

Andrew warns that doing nothing ensures the costs arrive anyway through trust erosion, lost contracts and compressed, high-risk migrations. “The window for leadership is open – the time for action is now.”