Piotr Z. Wieczorek

Dual-Metastability Time-Competitive True Random Number Generator

The paper introduces a new concept of a true random number generator (TRNG). Most metastability-based solutions operate on the uncertainty of a logical output state of a device (flip-flop, D-latch) aimed to be resolved from an exact metastable point. However, it has been shown that the metastable point of a bistable circuit (which is practically impossible to reach) does not guarantee absolute randomness or sufficient entropy. We propose the concept of a device in which the direct proximity of the metastable point is not mandatory. In our concept the transition times of two devices are compared. Such construction is less sensitive to the proximity of the metastable point, temperature fluctuations, and power supply instabilities. The paper briefly describes the metastability phenomena in general and other known metastability-based TRNG concepts. A new concept of a dual-metastability time-competitive generator is presented, analyzed both numerically and theoretically, and verified based on the sample circuits implementation. Empirical and statistical test results are presented.

An FPGA Implementation of the Resolve Time-Based True Random Number Generator With Quality Control

This article describes a novel concept of a true random generator (TRNG) which exploits random behavior from a nearly-metastable operation of groups of FPGA flip-flops in opposite to many deep-metastability-based TRNGs. The proposed concept harvests random behavior from the resolve time, which occurs in a wider range of flip-flops operation than the deep-metastability. Application of the resolve time randomness, requires the use of specially designed arbiter blocks. Presented TRNG provides a high stability of statistical quality which usually varies with PVT in similar solutions. Moreover, the use of an adaptive feedback loop increases robustness of the device. The article also describes the design considerations related to the adjustment of a flip-flop operating point, randomness extraction, and circuit fitting strategy.

An empirical study of transient responses of potentiometric ion sensors

The paper presents selected results of an empirical study of transient responses of ion-selective potentiometric sensor to two classes of stimulus. First, voltage time-domain response of ion-selective structures was observed to changes of ion concentrations in the sample, flow speed and electric load of the sensor. Presented results explain essential accuracy/precision limitations of ion concentration estimates that can be obtained in practical applications for clean water. Second, current time sensor response to small voltage stimulus was observed for different ionic content of the sample. A behavioral model was built, that can be used (along traditional steady-state model) for Data Fusion-based enhancement of multiple-sensor measurements.

Measuring and minimizing interrupt latency in Linux-based embedded systems

Paper describes performance of embedded real-time system controlled by Linux. Interrupt latency is taken into account as a main measured parameter in further considerations. To improve and minimize systems interrupt latency two separate approaches were evaluated. Obtained results proved that its possible to build a hard real-time system based on a modified Linux kernel.

Electrical properties of potentiometric sensors -an empirical study

The paper sums up investigations of electrical properties of potentiometric sensors that are under development in the EU FP6 WARMER project. There are 2 main goals of the empirical study: to determine minimum input resistance/bias current of data acquisition board and to determine the quality of analytical signal in DC and transient responses of the potentiometric sensors.

True Random Number Generator Based on Flip-Flop Resolve Time Instability Boosted by Random Chaotic Source

This paper introduces a new concept of a true random number generator (TRNG) based on two stages of randomness. The first stage is based on a novel chaotic circuit, which utilizes time as a continuous random variable in a feedback loop. The second stage is based on metastability; however, in contrast to known digital solutions, a flip-flop is stimulated by chaotic initial conditions. The advantage of chaotic behavior is the circuit’s immunity to active injection side-channel attacks (e.g., a frequency attack). The circuit design parameters can also vary in a wide range, which makes the TRNG insensitive to process, voltage and temperature (PVT) conditions and tolerance. Moreover, the design is extremely simplified, and therefore, feasible to implement in simple and inexpensive reprogrammable devices (no digital clock manager, programmable delay line, or phase locked loop are required). The TRNG ensures a constant (synchronous) 1-Mb/s bit rate output without additional post-processing. The randomness tests prove a high quality of an output bit stream, which is relatively high when compared with other solutions based on similar hardware resources.

Secure TRNG with random phase stimulation

In this paper a novel TRNG concept is proposed which is a vital part of cryptographic systems. The proposed TRNG involves phase variability of a pair of ring oscillators (ROs) to force the multiple metastable events in a flip-flop (FF). In the solution, the ROs are periodically activated to ensure the violation of the FF timing and resultant state randomness, while the TRNG circuit adapts the structure of ROs to obtain the maximum entropy and circuit security. The TRNG can be implemented in inexpensive re-programmable devices (CPLDs or FPGAs) without the use of Digital Clock Managers (DCMs). Preliminary test results proved the circuits immunity to the intentional frequency injection attacks.

Influence of radiation on metastability-based TRNG

This paper presents a True Random Number Generator (TRNG) based on Flip-Flops with violated timing constraints. The proposed circuit has been implemented in a Xilinx Spartan 6 device. The TRNG circuit utilizes the metastability phenomenon as a source of randomness. Therefore, in the paper the influence of timing constraints on the flip-flop metastability proximity is discussed. The metastable range of operation enhances the noise influence on a Flip-Flop behavior. Therefore, the influence of an external stochastic source on the flip-flop operation is also investigated. For this purpose a radioactive source of radiation was used. According to the results shown in the paper the radiation increases the unpredictability of the metastable process of flip-flops operating as the randomness source in the TRNG. The statistical properties of TRNG operating in an increased radiation conditions were verified with the NIST battery of statistical tests.

Versatile subnanosecond laser diode driver

This article presents a laser diode driver that provides a fast modulation of a laser beam. A pulsed current source was designed and built to test Infra-Red (I-R) receivers in the Time Domain (TD). The proposed solution allows to estimate pulse responses of various photodetectors, whereas the testing was performed with a PiN photodetector. The pulse response brings the information on the behavior of the device under test in a wide frequency range. In addition, an experimental application of the proposed method is presented too. System discussed in this paper has been fully designed and manufactured in Warsaw University of Technology (WUT) in Institute of Electronic Systems (ISE).

Measurement system for thermal drift of propagation time in fast pulse circuits

The paper presents a precise measurement system for the thermal drift of propagation delay in digital circuits. The design technique and essential units of system have been described. The method of short time estimation is also shown. Results of the time drift in popular bipolar and CMOS circuits are discussed. A brief explanation of significant drift of CMOS circuit delay has been shown.