Remember the Nokia N9? Probably not — but geek points if you do — because it was a smartphone that was DOA and used by pretty much no one. But even a three-year-old smartphone is pretty sophisticated piece of machinery. Using just an N9 and light, physicists have found a way to generate the random numbers algorithms used to encrypt data.
Modern cryptology algorithms rely on inputs of random numbers — if the numbers aren't truly random, the encryption get easier to crack. And computers, which are exquisitely good at following directions, are not good at being random.
One way to get random numbers is taking advantage of variations in the world of quantum mechanics, which usually requires bulky lab equipment. Light has inherent randomness. "According to quantum mechanics," writes William Herkewitz in Popular Mechanics, "it's impossible to predict exactly when an atom will emit a particle of light. And over a given amount of time, the exact number of light particles any light source will produce is also inherently random."
The Nokia N9 with its 8-megapixel camera is sensitive enough to detect this quantum variation. Each pixel of the camera detects a slightly different number of photons, a variation that gets translated into a stream of random numbers. The proof of concept suggests that equipment for quantum random generation can be radically shrunk down.
"If everybody on earth used such a device constantly at 1 Gbps," the authors write in their paper," it would take 1060times the age of the universe for one to notice a deviation from a perfectly random bit string."
A physicist not involved in the study told Popular Mechanics that there's no way to verify the randomness comes from quantum behaviour rather than other physical properties. But it does seem like viable way to generate random (or very very very close to random) numbers with some pretty unremarkable technology. [Popular Mechanics, ArXiv]