The threat

Although quantum computing entails many promising applications, it also poses a significant threat to the encryption schemes used in digital communication infrastructures. Cryptography is a key ingredient of cybersecurity technology and is used for encrypting email and device private messaging, certification of websites, digital signatures, bitcoins/blockchains and much more.

As a consequence, organisations relying on confidential digital communication that are already having to deal with many ‘classical’ cybersecurity threats, are now also having to prepare for the Quantum Threat, which includes taking into account that ‘harvest now, decrypt later’ attacks on confidential are already taking place.

CEO’s, CISO’s and COO’s are expected to protect current infrastructures and at the same time install adaptable safeguards against emerging quantum threats in the future. Introducing ‘crypto agility’, meaning the upgrading of the cryptography landscape to ensure the infrastructure is quantum-safe, is a process that can take 10+ years, especially in environments with legacy challenges.

Modern cryptography relies mostly on a-symmetrical mathematical challenges, such as multiplication and division. In summary, multiplying two large prime numbers is a quick and easy process, whilst decomposition (‘factorisation’) of a product of two unknown primes into their prime factors is a slow and cumbersome process. This disparity in difficulty is fundamental to the effectiveness and technical prowess of ‘public-key’ cryptography, which is widely used for secure online communication.

Historically, the task of factorization of large numbers has indeed been difficult to solve, both by human calculators and by automated approaches using conventional computing technology.

However, in 1994 Peter Shor developed a ‘quantum algorithm’ (now known as Shor’s algorithm) which can be seen as a recipe to simplifiy and significantly accelerate the factorization of large numbers. [REF weblink] Of course, Shor’s algorithm requires a quantum computer to threaten that protection that public key cryptography offers us at the moment.

Shor’s algorithm marked the first time that the remarkable capabilities of quantum computing were convincingly predicted for future practical use. This breakthrough altered our understanding of quantum computers and spurred more efforts and investment towards their physical creation and the development of new algorithms to harness their capabilities. It is projected that medium-sized quantum computers (~4000 logical qubits) combined with quantum algorithms will be able to break into Public Key Infrastructure much quicker than classical supercomputers, and that these medium-sized QC’s will emerge within the next decade (before 2035).”