Physicists Turn 8MP Smartphone Camera Into a Quantum Random Number Generator

KentuckyFC writes: "Random numbers are the lifeblood of many cryptographic systems and demand for them will only increase in the coming years as techniques such as quantum cryptography become mainstream. But generating genuinely random numbers is a tricky business, not least because it cannot be done with a deterministic process such as a computer program. Now physicists have worked out how to use a smartphone camera to generate random numbers using quantum uncertainties. The approach is based on the fact that the emission of a photon is a quantum process that is always random. So in a given unit of time, a light emitter will produce a number of photons that varies by a random amount. Counting the number of photons gives a straightforward way of generating random numbers. The team points out that the pixels in smartphone cameras are now so sensitive that they can pick up this kind of quantum variation. And since a camera has many pixels working in parallel, a single image can generate large quantities of random digits. The team demonstrates the technique in a proof-of principle experiment using the 8-megapixel camera on a Nokia N9 smartphone while taking images of a green LED. The result is a quantum random number generator capable of producing digits at the rate of 1 megabit per second. That's more than enough for most applications and raises the prospect of credit card transactions and encrypted voice calls from an ordinary smartphone that are secured by the laws of quantum physics."

Re:Always?

[Anonymous Coward]

You've got that a bit backwards. The underlying quantum physics concludes that everything is a random possibility in a range of probabilities, but that in a macroscopic scale the random fluctuations usually cancel out and the net result generally behaves as a deterministic process.

As related to this, if you power up a LED just enough for it to emit a single photon, you are pretty sure roughly what direction it went, but the exact path is unknown until it interacts with something. However if you juice up that LED to full power, you know that (aside from a few oddities every couple of years) every photon is travelling in the same illumination cone and the entire cone can be reliably modeled.

Re:This story is a dup

[timeOday]

I am not so sure the randomness from that project actually came from the quantum properties of the photons themselves. A saturated CCD may be a chaotic physical process, but (I think) the dynamics of that chaotic process are properties of that CCD, not directly from the actions of individual photons which are known to be "quantum" and truly random.

Be careful

[mbone]

The question is not really whether some physical process is random, the question is whether someone could predict some of the bits, say if you immersed the camera in a light field pulsed at the ccd refresh rate. Or an electromagnetic field that saturates the A/D converters wiring. Or...

The thing is that such a design has to be fixed, and then released in the field, and then be subjected to attacks tailored to its individual design and implementation, and there really is no magic bullet. So, "Counting the number of photons gives a straightforward way of generating random numbers" : maybe, but we won't know for sure if they are really and always random until it's been attacked for a few years.