Simultaneously, in the next decade or so, the massive processing power of quantum computers will render much of the current encryption unsafe – and specifically the public key cryptography used for key exchange. The threat today is that hackers, ranging from powerful states to criminals, can already download data in transit, and then decrypt it offline – either by brute force attacks today, or by using known algorithms on a quantum computer tomorrow. This means that governments or enterprises, which must protect some classifications of data for over five or even ten years, have a limited time frame to move to quantum-safe crypto solutions. In order to ensure continued confidentiality, they need to deploy such quantum-safe solutions already today.

QKD and quantum computing

Quantum Key Distribution (QKD) is a technology that exploits a principle of quantum physics – observation causes perturbation – to exchange cryptographic keys over optical fibre networks with provable security.

The principle of QKD is quite straightforward. According to quantum physics, the mere fact of observing a quantum object perturbs it in an irreparable way. Therefore, if one encodes the value of a digital bit on a single quantum object, a qubit, its interception will necessarily translate into a perturbation. This perturbation causes errors in the sequence of bits exchanged by the sender and recipient. By checking for the presence of such errors, the two parties can verify whether an eavesdropper was able to gain information on their key. QKD is used to generate two identical secure keys on the two ends of the channel. A Quantum Random Number Generator (QRNG) embedded in the QKD system guarantees that keys are produced in an absolute random way. Once the key exchange is validated, the keys can be used to encrypt data.