Kingston University: The Impact of Quantum Computing on Cyber Security - Online

An Online Frontier Technologies Awareness Event

Much of our information security depends on the fact that it is difficult even for the most powerful classical computers to factorise large semiprime numbers. However, a quantum computer could perform such factorisation quickly using a method known as Shor’s Algorithm.

This presentation, delivered by Dr Martin Tunnicliffe of Kingston University, examines the potential threat that quantum computing poses to current cryptographic systems, with a particular focus on RSA public key encryption. It explains how RSA security relies on the practical impossibility of factorising large numbers using classical computers, before exploring how quantum computers, through the use of qubits and superposition, could run Shor's Algorithm to perform this task with far greater efficiency. The session also covers the underlying mechanics of quantum logic, including Hadamard gates, CNOT gates, and quantum entanglement, to provide the technical grounding needed to understand how these systems operate.

The session will explore where quantum computing currently stands in practice, noting that the largest number factorised by a quantum computer to date is 48 bits, well short of the 2048-bit keys typical in RSA. Challenges such as decoherence, which limits how long qubits can maintain a superposed state, mean that RSA remains secure for now. The session concludes by introducing post-quantum cryptography, specifically lattice-based ciphers, as a likely direction for future-proofing encryption against advances in quantum technology.