Investigating Flicker Noise Effect on Randomness of CMOS Ring Oscillator based True Random Number Generators

The effect of flicker noise on randomness is one of the most controversial topics in random number generation. Flicker noise is random in nature; however, its power spectral density (PSD) exhibits a colored distribution, which indicates correlation between adjacent samples. The use of flicker noise for random number generation is risky (unlike white noise) due to its colored nature. Sampling is inevitable in random number generation and its effects should be taken into consideration. In addition, flicker noise gets folded during the sampling process, which leads to changes in its spectral properties. In this paper, the effects of flicker noise are investigated in order to address its usefulness for random number generation. The results show that flicker noise has positive effect on increasing the entropy in CMOS Ring Oscillator (RO) based Random Number Generators (RNGs).