Could Smartphone Cameras Lead Quantum Security?
Smartphone cameras could lead the next generation of security applications. Over at Medium, The Physics arXiv Blog discusses work recently completed by researchers at the University of Geneva who, using a Nokia N9 smartphone, were able to create random numbers at a rate fast enough to secure instances such as credit card transactions, emails, and phone calls. The group's research has shown that cameras are now advanced enough to detect quantum fluctuations in photon emission, and because of that fact, they can help tackle the problem of information security in a world heavily prepared to dismantle the status quo.
A Brief Background Of Light Emission
In order to understand how the researchers were able to achieve these feats, it is first necessary to understand a basic property of light as explained by quantum mechanics. The group's paper explains that light sources emit photons in a way that one cannot predict; “most light sources emit photons at random times,” it says. “This quantum effect is usually called 'quantum noise' or 'shot noise' and has been shown to be a property of the light field rather than the detector.” Aside from specific light sources such as amplitude-squeezed light, this property is constant and therefore will create the conditions necessary for the group to complete its experiment.
The Experiment Itself
The researchers used the Nokia N9's 8-megapixel camera and tested it against an 8-megapixel ATIK 383L monochrome CCD array, an image sensor device used in cameras that can convert photons into electron charges. The array made sure readings originating from the N9 were consistent and valid.
They allowed the devices to sense and measure the number of photons arriving at each pixel during specific periods. Smartphone cameras convert photons to electrons and then amplify those electrons according to their ISO settings.
On average, the number of photons should equal out to roughly the same amount for each device, but the specific number of photons should fluctuate from one period to the next. This difference between them is the random number generated by the camera. And because there are millions of pixels working at once, it is easy to derive many random digits at once during each period. Researchers shined a green LED at the N9's camera – enough to produce 410 electrons – and then used an extracting program to analyze the random digits that the entire process created.
The group says the process would need to repeat 10^118 times to show any sign that the digits were no longer random. That means, if everyone on Earth completed a similar process at 1 Gbps, humanity would need to continue working for 10^80 times the age of the universe to see even one digit that was not random.
As the Blog says: “That's not bad.”
Possible Struggles Ahead
Smartphones are not completely in the clear, yet. It is possible that they are too random.
Part of what makes traditional random number generators so expensive is that they can apply smoothing techniques to their data. As The Verge points out, “Pure chaos is often too messy to be workable.” In order to combat this problem, smartphones would need to apply a “whitening” function that would make the random data less random, less messy. And that could reduce its immediate effectiveness or its long-term feasibility.
Regardless of the hurdles, The Verge remarks, people such as Jon Callas, an American security expert associated with Silent Circle, are reportedly excited about randomness generators in smartphones. In addition, the researchers themselves say they believe the simplicity and performance of the smartphone used in their tests could “make the widespread use of quantum random numbers a reality.”
Image courtesy of Animist via Wikimedia Commons