1,721,041 research outputs found
True random number generators as configware for mixed mode programmable systems on chip
No full textThe internet of things (IoT) brings security requirements to novel classes of devices, that are resource constrained and significantly specialized, so introducing new challenges in the provision of cryptographic primitives including random number generators (RNGs). Conventional solutions use pseudo-RNGs (PRNGs) or piggyback on the on-board sensors to harvest environmental entropy, leaving some security concerns open in either way. A recent trend offers the opportunity to fix this issue. In fact, the extremely various requirements of the IoT pushes manufacturers to shift the boundaries of programmability, marketing systems on chip that join micro/application processors with reconfigurable logic, routing and analog parts. This enables the development of true-RNGs (TRNGs) library parts that can be dropped in projects as firmware/configware whenever needed. As a demo, the design of a USB TRNG dongle capable of almost 400kbit/s is illustrated on a Cypress PSOC prototyping kit
Achievement of preassigned spectra in the synthesis of band-pass constant-envelope signals by rapidly hopping through discrete sequences
No full textSpread-spectrum signals are increasingly adopted in fields including communications, testing of electronic systems, Electro-Magnetic Compatibility (EMC) enhancement, ultrasonic non-destructive testing. This paper considers the synthesis of constant-envelope band-pass waveforms with preassigned spectra via an FM technique using only a limited number of frequencies. In particular, an optimization-based approach for the selection of appropriate modulation parameters and statistical features of the modulating waveform is proposed. By example, it is shown that the design problem generally admits multiple local optima, but can still be managed with relative ease since the local optima can typically be scanned by changing the initial setting of a single parameter
Coding of stereo signals by a single digital ΔΣ modulator
No full textThe possibility of using a single digital ΔΣ modulator to simultaneously encode the two channels of a stereo signal is illustrated. From the modulated stream, the two channels can be recovered with minimal processing and no cross-talk. Notably, demultiplexing does not affect the sample-depth so that, after it, one still has a data stream suitable for directly driving a power bridge and convertible into analog by mere low-pass filtering. Furthermore, the approach is very flexible and if one channel is unused, it lets the other get improved dynamic range and SNR. The approach can take advantage of recent techniques for the design of ΔΣ modulators, including methods for psychoacoustically optimal distribution of quantization noise. Code is available to replicate the proposed examples and as a general computer aided design tool
Evaluation of a couple of true random number generators with liberally licensed hardware, firmware, and drivers
No full textSequences of high quality random bits are required in virtually all modern security and cryptography applications, pushing designers to devise hardware-based true random number generators (TRNGs). Alongside architectures made by big players of information technology and/or proposed via peer reviewed channels, many alternatives exist. The recent, powerful trend to interconnect even humble devices creates a significant deployment space for some of them, thanks to properties such as low-cost, good suitability to augment existing hardware, and readily available hardware/firmware/driver designs with liberal licenses. Consequently, there is practical relevance in a formal evaluation of their design. In this work, the "InfNoise" and "Redoubler" open architectures are investigated, finding them to belong to the chaos-based TRNG class and to bear similarity to some academic designs from the late'90s. Despite some some margins for improvement, the designs are found to admit formal justification
Bringing Data Converter Pairs into Chaotic Oscillation for Built-in Self-Test and Entropy Generation
No full textA pair comprising an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC) can enter chaotic oscillation when closed in a feedback loop with a limited set of additional elements. This phenomenon can be employed for entropy generation in true random number generators (TRNGs). Additionally, the oscillation can expose defects in the components’ operation, providing an opportunity for built-in self-test (BIST). Reconfigurable loops sustaining self-oscillation characterize the oscillation-based test (OBT) approach, appealing for not requiring resources to excite the blocks under test (BUTs). While OBT has been applied to various signal processing primitives, its use in data converters has been mostly confined to specific subsystems or variations of servo-testing. Here, it is shown that chaotic OBT of data converter pairs may offer insights on their input-output characteristics, while provid- ing entropy generation at the same time. A PIC microcontroller, together with an external DAC and some operational amplifiers, is used as a test bed to validate the approach’s scope and demonstrate its applicability to real-world systems
"Does the pathogenesis of AF vary in inherited structural heart disease and non-hereditary cardiac disease?"
No full textWe thank Drs. Stollberger and Finsterer for their letter concerning our recent manuscript on atrial fibrillation (AF) in inherited structural heart diseases (ISHD).(1) They raised important and provocative questions for which, very often, there are no definitive answers. Treatments/therapies of support of AF in ISHD, as well investigations aimed at assessing the different clinical expressions of the various ISHD, went largely beyond the scope of our review article and would have rather been subject-matter for a textbook chapter. This article is protected by copyright. All rights reserved
Optimal design of the noise transfer function of ΔΣ modulators: IIR strategies, FIR strategies, FIR strategies with preassigned poles
No full textRecently, strategies based on semidefinite programming (SDP) have been proposed for the design of the noise transfer function (NTF) of ΔΣΔΣ modulators. Contrarily to conventional approaches, these strategies can formally deal with diverse NTF optimality criteria. However, in most cases they only deliver finite impulse response (FIR) type NTFs that may require a high order to achieve the desired features and thus are not well suited for analog modulators. With a tutorial take, this paper reviews fundamental constraints and possible merit factors to be considered in the NTF selection, as well as conventional and recent design strategies, profiling the former for critical cases. Then, it shows how preassigned pole arrangements can be plugged into SDP based design methods. With this, a hybrid between conventional strategies (limited in flexibility) and recent ones (limited in requiring high orders) can be obtained, getting the best of both realms. Furthermore, this approach provides new insight on the quality of some choices made in conventional design methods
Excitations and signal processing for multiprobe setups
No full textThe possibility of taking advantage of multiprobe setups for ultrasound non-destructive testing (NDT) is introduced with reference to its physical and signal processing aspects. Preliminarily, a major distinction is made between phased-arrays and actual multi-transducer configurations. Then, most of the chapter is devoted to the latter type of setup. In this framework, the previously introduced channel model developed for single-probe operation, is extended to setups featuring multiple transmitting transducers (TXs) and receiving transducers (RXs) meant to be employed simultaneously in a so-called multiple input, multiple output (MIMO) configuration. It is also illustrated how this configuration relates to multi-user communication networks. Proper merit factors suitable for characterizing the performances of multiprobe systems are presented by taking advantage of the probabilistic system view introduced for single-probe systems. Finally, various classes of signals that can be adopted in MIMO NDT systems are described. These excitations may be designed according to random or deterministic approaches. In better detail, special techniques based on tessellation of the time-frequency (TF) plane are developed to design excitation signals capable of joining assuring contextually the good degree of appropriateness for MIMO setups and the good signal-to-noise (SNR) and resolution properties of chirps
Very low cost chaos-based entropy source for the retrofit or design augmentation of networked devices
No full textModern cryptographic protocols require good entropy sources. Unfortunately, many networked devices lack subsystems dedicated to this task, being potentially susceptible to random number generator (RNG) attacks. Yet, most of these systems allow software upgrades and host communication ports, providing the option of a retrofit. This work illustrates how chaotic dynamics can be used to design a sub-10$ entropy source capable of an over 48kbit/s rate and offering multiple serial communication abilities. Operation is based on a standard microcontroller and exploits a loop built around one of its analog to digital converters (ADCs). The design offers self-testing features and enables an experimental validation of some recent results on the choice of the best state quantization function to employ when using chaotic maps as RNGs
Circuito elettronico riconfigurabile come convertitore analogico/digitale e generatore di sequenze binarie autenticamente casuali
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