The global transition to quantum-safe cryptography is underway. The real challenge is not choosing between physics and mathematics, but rebuilding the systems of trust on which the digital world depends.
By Dr Najwa Aaraj, Chief Executive Officer, Technology Innovation Institute, and Chief Executive Officer, QuantumGate
Last week, the Nobel Symposium in Physics convened in Stellenbosch to examine the state of quantum computing. Nobel laureate Alain Aspect discussed the two quantum revolutions: the first gave us the transistor and the digital economy; the second, built on superposition and entanglement, is still unfolding. One of its most consequential implications is not what quantum computers will let us calculate, but what they may render insecure.
Much of today’s digital trust rests on public-key cryptography, which protects communication, authenticates identities and validates software updates. A sufficiently powerful quantum computer could break widely deployed algorithms such as RSA. The threat is not immediate, but neither is it hypothetical: encrypted information can be intercepted today and decrypted later. For anyone protecting information over decades, this is already a present-day concern.
Two approaches attract particular attention. Post-quantum cryptography uses mathematical algorithms designed to resist quantum attack. Quantum key distribution uses quantum physics to establish shared secret keys. They are often presented as competing paths. In reality they can address different parts of the problem, and the real question is how they coexist.
A global transition is already underway
The most significant development in quantum security is not a new processor but an international effort to replace cryptographic foundations before they become vulnerable. In 2024 the US National Institute of Standards and Technology finalized its first three post-quantum standards. The UK is targeting completed migration by 2035, the European Union is investing in quantum communication infrastructure, and China in quantum networks. Quantum security is becoming a matter of national infrastructure and sovereignty.
The real challenge lies in the infrastructure of trust
Yet standardizing algorithms is one challenge; integrating them into the infrastructure of digital trust is another. Hardware security modules, or HSMs, protect the most sensitive keys, and certificate authorities issue the certificates that let systems establish identity. Both must evolve. The new algorithms bring different key sizes and processing demands, and long-lived embedded systems will be especially hard to migrate. A quantum-resistant algorithm is not, by itself, a quantum-secure infrastructure.
Why hybrid cryptography matters
Post-quantum algorithms have been extensively evaluated, but their operational history is short. Hybrid key establishment combines a conventional mechanism with a post-quantum one, such as ML-KEM, so that confidentiality survives even if one is later found vulnerable. Two algorithms are not automatically better than one; the point is reducing dependence on a single set of assumptions. Signatures and certificates present different problems, easier for software based communications, but harder when used for hardware root of trust. Across all use cases, what matters most is cryptographic agility: being able to replace algorithms without redesigning a system, which may prove as important as the choice of algorithm itself.
Where quantum key distribution fits
QKD uses quantum states sent over an optical channel to establish shared keys, with security grounded in physics rather than computational difficulty. But it does not encrypt information by itself, nor replace authentication or signatures. It needs dedicated optical infrastructure, has distance limits, and long-distance deployments often rely on trusted intermediate nodes. That makes it most relevant for selected high-value links between government facilities or critical data centers.
Combining physics, mathematics and secure hardware
The next stage may be defined less by competition between QKD and PQC than by their integration. Between two highly sensitive facilities, one layer might establish secrets through hybrid cryptography and another add key material through QKD, with HSMs protecting the keys and post-quantum signatures authenticating the systems. Each addresses a different risk. For everyday enterprise and internet services, standardized PQC is the practical route, and the Internet Engineering Task Force’s formalization of hybrid key agreement for TLS 1.3 in August 2026 is a significant step.
The quantum threat is advancing on two fronts
Physical qubit counts are a poor measure of a machine’s ability to threaten cryptography; what matters is reliable computation on error-corrected logical qubits. In 2019, one influential estimate put factoring a 2048-bit RSA key at about twenty million noisy qubits. By 2025, improved methods had brought comparable estimates below one million, albeit with different assumptions and longer run times. Theory can move the threat without new hardware. For information that must stay confidential for decades, waiting for certainty is not a defensible strategy.
Building the next generation of digital trust
At the Technology Innovation Institute, our work spans these dimensions. Our Quantum Research Centre designs and fabricates superconducting quantum processors. Our cryptographers helped advance two digital signature schemes into the third round of NIST’s additional signature process. And with our partners at VentureOne we are taking entanglement-based quantum key distribution toward commercial deployment. These are not interchangeable solutions, and the next challenge is connecting them to the infrastructure organizations depend on.
For most digital systems, post-quantum cryptography will be the foundation, with hybrid approaches as the migration path and QKD protecting selected critical links. The goal is not to make every system quantum-based, but to secure the systems society depends on. The first quantum revolution transformed computing. The second will test the foundations of digital trust. Our success will be measured not only by the quantum computers we build, but by whether we can secure the digital world before those computers can break it.
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