Quantum computing is expected to revolutionise our approach to many current technological and scientific challenges. Their unprecedented computational power – beyond anything achievable by classical computers – has the potential to make substantial contributions to energy efficiency, drug discovery, logistics and transportation, and machine learning. Their ability to process immense volumes of data will progress foundational scientific problems, for example in space exploration or the origins of the universe. If anything, quantum computing’s full potential is so hard to envisage, it is often difficult for scientists to predict the kind of problems it can offer solutions to. What no one is in any doubt though, is the threat fully developed quantum computers will pose to existing cryptographic systems currently protecting our digital infrastructure – from finance and banking, to e-commerce, private healthcare or employment data, and sensitive government information. A new briefing published by the Parliamentary Office for Science and Technology (POST) provides some useful insights into this problem and considers the UK’s capability to combat this threat.  

POST is an impartial research and knowledge exchange service based in the UK Parliament. Its purpose is to conduct independent review of emerging research into critical and complex scientific and social issues, in consultation with expert stakeholders, and to summarise these findings into clear, brief summaries for members of both houses of parliament.  

POST’s recent briefing into the potential effect of quantum computers onto digital security provides an excellent introduction to this topic. It considers how public key cryptography (PKC) works, discusses Shor’s algorithm (the mathematical proof showing that a powerful enough quantum computer could break existing forms of PKC), introduces the concept of post-quantum cryptography (PQC – the development of quantum resistant mathematical cryptography), and lays out a timeline for the realisation of the quantum computing threat. The briefing concludes by summarising the UK’s response to this challenge: the National Cyber Security Centre’s recommendations for migration of all sensitive systems to PQC, the substantial UK government investment into further development of quantum technologies and skills (including towards quantum secure and quantum safe products and services) and the work of the National Quantum Computing Centre’s into developing the country’s future quantum computing infrastructure.

The POST briefing onto the threat posed by quantum computing to digital security is available to read here.