RAVA: An Open Hardware True Random Number Generator Based on Avalanche Noise

Entropy is a crucial resource in the domains of cryptography, artificial intelligence, and science. This paper introduces RAVA, a true random number generator based on avalanche noise. RAVA is an open-source device designed to offer a transparent and customizable platform, making auditable and high-quality entropy accessible to a wider audience. The device employs a differential design, which involves comparing two similar noise sources to mitigate the impact of environmental factors. Furthermore, RAVA incorporates a dual entropy core architecture featuring two independent entropy channels that generate random bytes simultaneously. A stochastic model is theoretically derived and empirically confirmed, offering valuable insights into the entropy extraction mechanism and allowing the estimation of the minimum bias attainable. An implementation is presented as a discrete circuit with an ATmega32U4 microcontroller including a USB interface, achieving an unbiased throughput of 136.0 Kbit/s without the necessity of post-processing algorithms. The generated random bytes are evaluated for bias and serial correlation, their entropy is assessed using NIST SP 800-90B estimators, and the randomness quality is verified using the NIST 800-22R1a test suit. For comparison, the same tests are applied to a commercial device based on quantum optical phenomena, revealing similar distributions for both devices across the studied metrics.