In this paper, the guidelines to design a true random bit generator (TRBG) circuit with a predefined minimum entropy are discussed. The approach is proposed for a TRBG based on a one-dimensional piecewise-linear chaotic map; it does not require bit throughput reduction, and it is suitable for the development of integrated TRBG circuits. In particular, the proposed design strategy is based on a feedback control procedure that allows to dynamically change the system parameters for the correction of the circuit "nonidealities" (e.g., the circuit offsets). The correction algorithm does not require a direct measurement of the system "nonidealities" or of the effective value of the map parameters, but only a dynamic estimation of these quantities based on the observation of the TRBG output. The design approach is validated by a hardware prototype implemented on a field-programmable analog array. The results of the NIST FIPS 140-2 test suite, the DIEHARD test suite, and the Coron's Universal test, applied to the TRBG output sequences before and after a simple post processing without throughput reduction, are reported and discussed.

In this paper, a family of nonlinear congruential generators (NLCGs) based on the digitized Reacutenyi map is considered for the definition of hardware-efficient pseudorandom number generators (PRNGs), and a theoretical framework for their study is presented. The authors investigate how the nonlinear structure of these systems eliminates some of the statistical regularities spoiling the randomness of sequences generated with linear techniques. In detail, in this paper, a necessary condition that the considered NLCGs must satisfy to have maximum period length is given, and a list of such maximum period PRNGs for period lengths up to 2³¹-1 is provided. Referring to the NIST800-22 statistical test suite, two PRNG examples are presented and compared to well-known PRNGs based on linear recurrencies requiring a similar amount of resources for their implementation

In this paper, the discretized Tent map is analyzed as a source of pseudorandom bits. To evaluate the performance of the proposed pseudorandom bit generators (PRBGs), different issues were considered, such as the period length, the statistical characteristics of the generated bit sequences, and the hardware complexity required in digital circuit implementations. The results show that, under proper design conditions, the Tent-map-based PRBGs represent a suitable alternative to other traditional low-complexity PRBGs such as the linear feedback shift registers

The aim of this work is to investigate the gas sensing performance of single wall carbon nanotubes (SWCNTs)-based conductive sensors operating at low–medium temperatures (<250 °C). The investigated sensing films consists of an SWCNT network obtained by drop-casting a SWCNT suspension. Starting from this base preparation, different sensing devices were obtained by decorating the SWCNT network with materials suitable for enhancing the sensitivity toward the target gas. In particular, in this paper, nano-particles of gold and of TiO₂ were used. In the paper, the performance of the different sensing devices, in terms of response time, sensitivity toward NO₂ and cross-sensitivity to O₂, CO and water vapor, were assessed and discussed. Sensors based on decorated SWCNT films showed high performance; in particular, the decoration with Au nano-particles allows for a large enhancement of sensitivity (reaching 10%/1 ppm at 240 °C) and a large reduction of response time. On the other hand, the addition of TiO₂ nanoparticles leads to a satisfactory improvement of the sensitivity as well as a significant reduction of the response time at moderate temperatures (down to 200 °C). Finally, the suitability of using Au decorated SWCNTs-based sensors for room temperature sensing is demonstrated.