Within the next decade, advances in quantum technology will result in sufficiently powerful machines that could undermine today’s encryption standards.

Experts have warned that the shift to post-quantum cryptography poses real risks to cybersecurity, digital trust and long-term business resilience. This means quantum security is no longer a distant threat but a pressing governance issue. For boards overseeing cybersecurity risk, supply chain exposure and long-lived sensitive information, the question is no longer whether quantum attacks are possible, but whether the organisation is prepared to remediate current encryption vulnerabilities before quantum computing power makes them exploitable at scale.

The message is clear: quantum readiness requires planning now.

What actually changes when quantum computers arrive?

Associate Professor Sushmita Ruj, Faculty of Engineering Lead, UNSW Institute for Cybersecurity, IFCYBER, and Cybersecurity and Trustworthy Systems Theme Co-Lead in the School of Computer Science and Engineering, says that not all quantum machines pose a threat to current encryption methods.

“Cryptographically relevant quantum computers have the power to break currently used public key algorithms like RSA, ECDSA, which are the backbone of many communication protocols and secure applications. Much of the encryption today relies on algorithms like RSA and elliptic curve cryptography. These will no longer remain secure.”

Post-quantum cryptography is essentially a new way of ‘locking’ up information so that even very powerful future computers – quantum computers – won’t be able to break the ‘lock’. The encryption and authentication algorithms used to keep data safe today – the ‘locks’ like RSA and other common public key algorithms – work well against conventional computers, but they could be easily cracked by more advanced quantum computers.

“This has a strong impact on personal data like health data, credentials, as well as sensitive government and corporate information,” says A/Prof. Ruj.

Public key systems such as RSA and ECC underpin secure web browsing, digital signatures, authentication protocols and secure data exchange across supply chains. If broken, the impact would extend across providers, customers and global digital ecosystems.

A/Prof. Ruj says that although the exact timeline for deploying this new technology remains uncertain, the direction is clear. “With the advancement of quantum computing, the risk is pretty high. Though we might not have cryptographically relevant quantum computers for another 5-10 years, the transition process is so slow that if we don't start now, then it will be hard to change to quantum-safe systems overnight,” she says.

Learn more: When AI becomes a weapon in the cybersecurity arms race

“To give some numbers, currently we have quantum computers with a little more than 1000 qubits; a cryptographically relevant quantum computer might potentially need around a million qubits to break RSA-2048 [a very large digital key that’s extremely difficult to crack].”

The implication for risk management is significant. Even if cryptographically relevant quantum computers are years away, sensitive information encrypted under current encryption systems today will be exposed later.

The “harvest now, decrypt later” problem

Öykü Işık, Professor of Digital Strategy and Cybersecurity at IMD, explains that a quantum computer is not just “a faster computer.” It’s a completely different kind of machine.

“For a narrow (at least, currently) set of problems, it can use different physics to explore solution spaces in ways classical computers can’t. The main security issue resulting from this is that, if a sufficiently capable quantum computer becomes publicly accessible/ commercially available, it can undermine the assumptions behind widely used public-key algorithms that power our web security infrastructure, such as data encryption, user authentication, digital signatures, etc.”

Prof. Işık explains that modern digital trust is grounded in the mathematical hardness assumptions behind cryptographic algorithms. In practice, security depends on encryption schemes built on problems that classical computers find computationally infeasible to solve at scale.

“Quantum computers, however, will be able to solve these math problems effortlessly. Even though the transition to quantum computers may be slow, the breakthrough (through wide availability) will be sudden. That is why being ready is so important.”

One of the most concerning quantum threats is known as 'harvest now, decrypt later'. “It means attackers can steal encrypted data today, store it, and decrypt it later when quantum capability makes that feasible,” explains Prof. Işık.

“That turns quantum into a delayed-breach problem: the theft happens now, the damage can arrive years later. Boards should care because it changes the risk profile of long-lived sensitive data (such as IP, strategy, customer records) where confidentiality must hold for a decade or more. Unfortunately, we know that this (stealing encrypted data) has been happening already for several years now.”

For sectors handling long-lived data – including healthcare records, financial services data, and government systems – quantum risk then becomes a strategic governance issue, not just a technical vulnerability.

Why post-quantum cryptography is not a simple upgrade

A/Prof. Ruj says business leaders often assume post-quantum cryptography is a simple swap for existing classical encryption and signature algorithms, but that this is not the case.

“There have been efforts around the world, with some algorithms being standardised by the National Institute of Standards and Technology. It is often easy to think, why don't we replace a classical algorithm with a PQ algorithm? It's not easy to plug and play. Partly because there are performance bottlenecks associated with post-quantum cryptography algorithms, which impact the quality of service.

Learn more: Company directors fall short of cyber security skills mark

“Some like SHL_DSA have large signature sizes, whereas ML-DSA have large public key sizes. Larger keys and signatures increase bandwidth, storage and processing demands. Added to this, there are legacy systems, which are hard to upgrade.”

And where organisations get stuck is often around costs and uncertainty. “Post-quantum cryptography transition is expensive, it’s expensive because it requires upgrading systems and processes and investing in capacity building and training,” says A/Prof. Ruj, who adds that many organisations “are not convinced it's worth the money spent for such upgrades”.

At the same time, while new infrastructure support, products and services are available, choosing a well-tested, stable and reliable one can be hard for organisations. “Many solutions are not standardised and therefore carry some associated risks,” she says.

Unlike AI, whose productivity gains and profit potential are visible even to everyday users, post-quantum cryptography offers no immediate or obvious commercial upside. “In the case of post-quantum cryptography, individual customers cannot see the immediate value. Post-quantum cryptography might not generate immediate revenue for organisations, but what it can do is to save millions of dollars that can otherwise be lost in quantum attacks,” she says.

What boards should be asking now

Prof. Işık warns that waiting only compounds exposure. “Waiting only shrinks your options. You accumulate cryptographic debt as new systems hard-code today’s algorithms, while the eventual migration becomes bigger, costlier, and more rushed. And when the industry flips, everyone will scramble at once – vendors, auditors, certificate authorities, consultancies – exactly when you don’t want to be improvising.”

She urges boards to move beyond abstract monitoring and towards concrete risk assessment:

• What data must remain confidential for 10+ years, and where is it stored?
• Where do we rely on public-key cryptography across critical systems? Do we have an inventory?
• How crypto-agile are we? Can we swap algorithms without redesigning systems?
• Which key vendors/partners have access to our sensitive data, and do they have a post-quantum roadmap?
• Do we have a transition plan with owners, milestones, and a budget?

“If management can’t answer these precisely, the organisation is not ready, only optimistic,” she says.

Subscribe to BusinessThink for the latest research, analysis and insights from UNSW Business School

A/Prof. Ruj adds that technical literacy at the governance level is essential. “My first suggestion to the board is to have well-qualified cybersecurity technical experts. This is a highly technical problem, and failing to understand its magnitude and the proper approaches to address it can lead to improper company policies and decisions.

“They should start preparing now. Their customer data is at risk, which could cost them more than the cost of migration. Delaying the process of migration means that they might later have to make decisions in a hurry and are prone to making mistakes.”

The Australian Signals Directorate has issued migration guidance, and comparable frameworks exist internationally. Organisations should follow the suggested timelines, as transitioning to post-quantum cryptography is a gradual process that cannot be completed quickly.

A/Prof. Ruj says: “It is a very slow process and needs time and effort. So, the earlier they start, the better. The organisation should begin understanding risks and prioritising the post-quantum cryptography migration. This would include building an inventory of crypto assets, finding dependencies between them, evaluating the risk, and taking a phased approach to post-quantum cryptography migration.”

This is also where training and awareness are extremely crucial, where universities, government and industries can play an important role. “There is a need for extensive discussions between technology and policy experts to ensure that the technology implementation is backed by strong policies and regulations,” she says.

Learn more: Data breach reporting crisis: How delays impact cyber insurance risks

The governance test of the quantum era

Prof. Işık says regulators, customers and partners will increasingly expect credible quantum readiness. “I do not believe customers, partners, and regulators would expect perfection, but they will expect credible preparation. ‘We haven’t started’ will increasingly imply weak governance: failing to anticipate a foreseeable, material risk with long lead times.

“In trust-based ecosystems, laggards become the weak link – commercially (partner friction), operationally (interoperability issues), and reputationally (questions about data stewardship).”