In this paper, we evaluate clock signals generated in ring oscillators and self-timed rings and the way their jitter can be transformed into random numbers. We show that counting the periods of the jittery clock signal produces random numbers of significantly better quality than the methods in which the jittery signal is simply sampled (the case in almost all current methods). Moreover, we use the counter values to characterize and continuously monitor the source of randomness. However, instead of using the widely used statistical variance, we propose to use Allan variance to do so. There are two main advantages: Allan variance is insensitive to low frequency noises such as flicker noise that are known to be autocorrelated and significantly less circuitry is required for its computation than that used to compute commonly used variance. We also show that it is essential to use a differential principle of randomness extraction from the jitter based on the use of two identical oscillators to avoid autocorrelations originating from external and internal global jitter sources and that this fact is valid for both kinds of rings. Last but not least, we propose a method of statistical testing based on high order Markov model to show the reduced dependencies when the proposed randomness extraction is applied.

Abstract-The objective of this paper is to provide insight on the design, evaluation and testing of modern True Random Number Generators (TRNGs) aimed towards certification. We discuss aspects related to each of these stages by means of two illustrative TRNG designs: PLL-TRNG and DC-TRNG. Topics covered in the paper include: the importance of formal security evaluations based on a stochastic model of the entropy source, the development of suitable and lightweight embedded tests to detect failures, the implementation and testing of TRNGs in dedicated FPGA platforms, and a robustness assessment to environmental and/or physical modifications.

Physical unclonable functions in field programmable arrays are always linked to the used hardware. Therefore, it is necessary to have high amount of simple devices for evaluation purposes. One of the suitable platform for such evaluation is HECTOR Evaluation Platform. The following paper describes this platform, compares it with existing solutions, and shows several examples of its using. The proposed platform consists of a motherboard and exchangeable daughter board modules. These are designed to be as simple as possible to allow cheap and independent evaluation across many devices. In comparison to similar existing solutions, proposed platform excels in its simple architecture, which allows remote using of module. The platform is also suitable for evaluation of other cryptographic primitives like true random number generators, encryption systems, and etc. Platform's components are adjusted for side channel attacks measurements. HECTOR evaluation platform was designed and optimized to fulfil the European HECTOR project (H2020) requirements.

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.

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