Researchers at Taiwan's National Tsing Hua University have built a true random number generator small enough to provide security for NFC chips, according to a report from IEEE Spectrum. Using so-called "memristors" — chips which store memory as resistance rather than as electrical charge — the generator produces random numbers at a rate of 1 KHz on its own, or more than 100 MHz with an attached feedback circuit.

True random numbers are notoriously difficult to generate, usually requiring significant amounts of space and power. This new system undercuts existing generators by harnessing a completely new process, using the natural trapping and releasing of electrons in a silicon dioxide film to produce the numbers.

"The random codes we get from the fluctuation will never be known," one researcher tells IEEE Spectrum. "This will help improve existing encryption schemes." Aside from NFC systems in phones and smart tags, possible uses for the technology include low-power devices such as car keys and ID cards.