Assurance of Quantum Random Number Generators Data is one of the world’s most valuable commodities, it affects every person, company and government, everywhere. Most of the world’s cybersecurity infrastructure is based on the exchange and use of digital cryptographic keys; random number generators (RNGs) are essential to this infrastructure and newer technologies such as quantum key distribution. Current tests for random number generators can give information about the statistical properties of their output but cannot assure that the output is unknown to others. There is currently no process that can assure that the numbers generated are unique and hence unpredictable, which potentially compromises security. Quantum random number generators (QRNGs) utilise the inherent randomness of natural physical processes to create their output, assured unique to each device if the process is quantum. They are thus superior to RNGs as they produce truly random numbers, with no risk of the same random sequence being produced by identically manufactured and prepared QRNGs. A method for providing authoritative certification of the unique randomness produced by QRNGs does not currently exist. Modelling and experimentally testing the physical process used to create a QRNG’s output can be used to evidence its quantum nature, and hence its randomness and uniqueness. This project will address this need for certification to accelerate the commercial and industrial exploitation of QRNGs; it has received £2.8m of Innovate UK ISCF funding, an additional £1.6m of co-funding from the industrial partners and complementary research in the EPSRC Quantum Communication Hub. The project consortium is led by the National Physical Laboratory (NPL), the UK’s National Metrology Institute. Key partners are the UK’s leading developers of optical quantum random number generators (QRNGs) – Cambridge Quantum, Crypta Labs, KETS Quantum Security Limited, Nu Quantum, Quantum Dice, Toshiba Europe Limited – and Swiss market-leader ID Quantique. Academic expertise is provided by University of York and University of Kent. The National Cyber Security Centre is a collaborator. The Quantum Communications Hub, through its partnership resource, previously helped to fund a feasibility study on QRNG assurance, which served as the model underpinning this new programme of work.