Abstract
A remarkable aspect of quantum theory is that certain measurement outcomes are entirely unpredictable to all possible observers. Such quantum events can be harnessed to generate numbers whose randomness is asserted based upon the underlying physical processes. We formally introduce, design, and experimentally demonstrate an ultrafast optical quantum random number generator that uses a totally untrusted photonic source. While considering completely general quantum attacks, we certify and generate in real time random numbers at a rate of with a composable security parameter of . Composable security is the most stringent and useful security paradigm because any given protocol remains secure even if arbitrarily combined with other instances of the same, or other, protocols, thereby allowing the generated randomness to be utilized for arbitrary applications in cryptography and beyond. This work achieves the fastest generation of composably secure quantum random numbers ever reported.
- Received 21 June 2019
- Revised 27 August 2020
- Accepted 21 September 2020
DOI:https://doi.org/10.1103/PhysRevX.10.041048
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Random numbers are a key element in science and engineering with applications such as cryptography, numerical simulations, lotteries, and gaming. Quantum mechanics—because of its inherent randomness—prevails as a means to generate genuinely random numbers. Methods used to leverage quantum randomness must balance speed, trust in the inner workings of the apparatus, and security against attacks. Using commercially available components, we experimentally demonstrate an ultrafast optical quantum random number generator for which we certify, in real time, random numbers at a rate of , totally independent of the optical source and with rigorous composable security (the most stringent security definition for which any given protocol remains secure even if arbitrarily combined with other instances of the same, or other, protocols). This work achieves the fastest generation of composably secure quantum random numbers ever reported.
While assuming our setup’s light source to be controlled by an eavesdropper, we carefully model our measurement apparatus and derive the optimal strategy for the eavesdropper to cheat our protocol. Our resulting certified estimate of the randomness is thus totally independent of the input light and hence safe from the myriad of associated attacks. Additionally, we provide a composable security parameter that is tunable according to one’s desired application. Finally, we perform state-of-the-art real-time postprocessing with dedicated programmable electronics.
Our protocol allows the randomness to be utilized in arbitrary applications. We expect this powerful combination of speed, practicality, and security to have a significant impact throughout cryptography and computer science.
