Why quantum computing changes the cybersecurity baseline
Quantum computers exploit superposition and entanglement to solve problems, including integer factorization, far faster than classical machines. Those are exactly the problems RSA, Diffie–Hellman and elliptic-curve cryptography rely on. A sufficiently large quantum computer would break the public-key cryptography protecting most of today’s internet traffic.
“Harvest now, decrypt later” means the risk window has already opened: intercepted ciphertext can be decrypted retroactively once hardware matures.
Two responses, one strategy
| Post-Quantum Cryptography (PQC) | Classical algorithms resistant to quantum attack. Standardized by NIST in 2024. |
| Quantum Key Distribution (QKD) | Physics-based key exchange, secured by quantum mechanics rather than computational hardness. |
QKD via Fibre
QKD encodes cryptographic key material onto individual photons; any interception disturbs their quantum state, revealing an eavesdropper, a guarantee rooted in physics.
Design considerations
| Coexistence | Quantum and classical channels on shared fibre via wavelength multiplexing |
| Range class | Metro fibre, up to 120 km |
| Deployment | Point-to-point or trusted-node mesh for national backbones |