A2 Solutions to counter quantum threat There are two very different classes of solutions, which should be combined to counter the quantum threats of the future. The first class of solutions, which relies on computation, aims to replace existing algorithms that are vulnerable to quantum computers with new ones, known as quantum-resistant algorithms (QRA). These approaches are often referred to as post-quantum cryptography (PQC). These are entirely based on mathematics implemented on classical computers and do not involve quantum technologies. PQC will undoubtedly form the first line of defence and will be exploited in all general-use applications. Several PQC algorithms have now been standardized by the National Institute of Science and Technology (NIST) to replace the quantum-vulnerable ones currently in use.37 Organizations are steadily working out implementation. There must be a period where both current and PQC algorithms work concurrently, making the transition more complex than simply replacing a few algorithms. Telecommunication companies are harnessing cryptographic inventory, analytics and PQC to enhance security for government, customers and society. The second class of solutions is based on quantum technologies. It includes both quantum random number generation (QRNG) for key generation and other cryptographic purposes, and quantum key distribution (QKD) for sharing keys across networks in a secure manner. When implementing QKD, there’s a vital choice between using the earlier and more widely used prepare-measure approach or a newer, more-advanced quantum-entanglement approach.QRNG can be used to generate randomness for most applications. It is the most mature application of the quantum technologies. QRNGs are available in different formats and form factors, for applications ranging from small IoT devices, smart phones, computers and data centres. Some are even space-qualified for use in satellites and some harness 5G smartphone equipped with a QRNG chipset.38 QKD has a more targeted application and is used to enhance security in specific applications. It requires physical infrastructure and hardware components, which must be added to existing network infrastructure. Its initial application was direct data centre to data centre connection, with a limited maximum distance of the order of 100 km. Today, this has expanded to encompass terrestrial fibre networks with longer distances and complex connectivity. Several large networks are now operating or in various stages of completion worldwide, including the QKD networks in China, the Euro-QCI in EU, the Nation-wide Quantum Safe Key Distribution Network in South Korea and the Nation Quantum-Safe Network Plus (NQSN+) in Singapore.39 Since QKD networks require physical infrastructure, they are best designed and operated by telecommunication organizations. The NQSN+ is a good example of a QKD and PQC network operated by a telecommunication organization for various types of customers. These two classes of solutions have very different pros and cons and should therefore be combined if possible to offer the best defence-in-depth security. Quantum Technologies: Key Strategies and Opportunities for ICT Leaders 21

Quantum Technologies Key Strategies and Opportunities for ICT Leaders 2025