No random number generator you’ve ever used is truly, provably random – but this one is. Researchers have used an experiment developed to test quantum mechanics to generate demonstrably random numbers, which could come in handy for encryption.

“With standard random number generators, there’s no real way to put a certificate of randomness on it,” says Peter Bierhorst at the US National Institute of Standards and Technology in Boulder, Colorado. “With this one, it’s guaranteed to be random by the …