A Comparative Study on the Robustness of ChaosBased Random Number Generators This paper presents a comparative study on continoustime chaosbased random number generation methods regarding their robustness against changes in chaos controlling parameters and external interference. Chaotic systems suggest enabling high throughput random data without need for postprocessing and with less complex hardware. However, due to effects of aging or fabrication process variations, the chaos controlling parameters of the random number generator may change. Furthermore, external interference can be applied on the chaotic oscillator to manipulate its output. Therefore, in a chaotic RNG, the bit generation method should be immune to parameter variation and external interference. In this study, two widely used methods for random number generation have been compared: 1) Regular sampling of chaotic waveform (RSCW), and 2) Chaotic sampling of regular waveform (CSRW). A doublescroll chaotic system is chosen as the chaotic oscillator and it is numerically simulated in normalized time domain to generate random bit sequences using both methods. Applying the concepts of autocorrelation and approximate entropy to the output bitstreams, the robustness of the two bit generation methods against parameter variation and external interference have been compared. It is demonstrated that chaotic sampling of regular waveform method provides more robustness against parameter changes and external interference compared to regular sampling of chaotic waveform method.

A Robust Random Number Generator Based on Chaotic Ring Oscillators A robust chaosbased random number generator (RNG) system is newly proposed. Output bitstreams generated from this new RNG system is tested on NIST80022 test suite. Proposed RNG circuit fulfill all fifteen randomness tests of NIST80022 without undergoing any postprocessing implementations except for the X OR operation. While classical ring oscillator based RNG systems needs at least 25 rings, each of them containing 13 inverters, and 25 D flipflops to pass all the tests, newly designed RNG system pass all the tests successfully with 10 chaotic new subcells containing 20 ring oscillators with 13 inverters and each subcell includes two resistors, a capacitor and two diodes. These are enough for the new system to generate sufficient randomness without any D flipflops. Experimental results are demonstrated and comparisons are made among the new design, classical ring oscillator based RNGs and another chaotic ring oscillator based RNG. Noise analysis of the new RNG is also performed to show that the system has a nondeterministic entropy source which secures the system against possible synchronization attacks.