Quantifying entropy is important for cryptography. Statistical testing can only give estimation, not certainty, and is flawed in the sense that good pseudorandomness can pass statistical tests, whilst perfect randomness will sometimes fail. One approach to entropy estimation is to thoroughly model the stochastic process of the underlying noise source. However, this requires assumptions that this theoretical model perfectly matches the real world implementation, which is highly unlikely in practice.
In this talk we describe device independence, an alternative approach to measuring entropy that uses quantum physics to give a concrete lower bound on the entropy produced by a source, as part of real-time real-life entropy generation. We will then discuss practical barriers to implementing this approach today, and a halfway house where the entropy measurement is conditioned on the assumption that specific active attacks have not taken place.
Matty Hoban is a Senior Research Scientist in Quantum Cryptography at Quantinuum. He obtained his PhD in Quantum Physics from UCL where he worked on quantum computing. Prior to his current role, he has held postdoctoral research positions in physics and computing departments at the University of Oxford, the University of Edinburgh and ICFO-Institute of Photonic Sciences, and was a lecturer at Goldsmiths, University of London.