Low-cost ARM Cortex-M0 Based TRNG for IoT Applications

The Internet of Things (IoT) is one of perspective electronic sectors. In the near future a lot of common devices from a refrigerator to a door lock will be connected to the internet. Protection of the IoT devices should not be neglected. The device security is composed of many safety levels, where every countermeasure increases its robustness. The paper describes an implementation of a True Random Number Generator (TRNG) used in many cryptographic algorithms and protocols. It is based on a modern low-cost and low-power STM32F050 ARM-M0 microcontroller, suitable especially for IoT applications. The main motivation for developing of such generator was its absence in lower members of microcontroller families. Integrated TRNG uses common features of the microcontroller, which may be portable across ARM-M0 architecture. A source of randomness is instability of internal RC oscillator, which is acquired using another faster clock and one timer. The paper follows a previous research, but using the modern microcontroller with proposed on-line embedded tests which are designed in order to be simple and effective.