Random number generator goes nano for stability

Random number generation is used to encrypt and secure data and generate one-time passwords. Generating a random number requires a circuit to detect the random noise produced by a physical component, such as thermal noise from diodes or resistors. The power consumption of these elements can be significant in highly integrated low-power applications, and the degree of randomness can degrade over time due to a change in the device’s physical and electronic characteristics.

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Mario Lanza, an Associate Professor of material science and engineering at KAUST, Saudi Arabia, saw an opportunity for memristors to be used as more reliable true random number generators (TRNGs).

“Memristors are meta/insulator/metal nanocells based on two-dimensional materials that have fast operation speed, low energy consumption and very long endurance and data retention time, as well as being very easy and cheap to fabricate,” Lanza said in a statement. “For this reason, memristors are being intensively explored for applications such as high-density electronic memories. They are also particularly useful for encryption systems because they can produce fluctuating electronic signals with an extraordinarily high degree of randomness.”

Memristors – or memory resistors - are passive electronic components whose resistance can be switched between two states by applying electrical stress. They also produce random telegraphic noise (RTN), which is said to be ideal for random number generation.

“The main challenge was that the atomic structure of the resistive thin film degrades over time, which causes the RTN signal to disappear,” said Lanza. “In our devices, we used two-dimensional multilayer hexagonal boron nitride, which is a two-dimensional material that has a very stable atomic structure and is immune to this effect.”

The team fabricated hundreds of devices using industry-compatible methods and characterised them using a range of techniques including a randomness test involving the generation of one-time passwords.

“A key aspect of our work was the use of fabrication processes that are compatible with industry, which facilitates integration in commercial products,” Lanza said. “We also presented yield and variability information for hundreds of devices; it was a tremendous effort, but it gives more reliability to our study.”

The team’s findings have been published in Advanced Materials.