Cryptanalysis of a Random Number Generator Based on a Chaotic Circuit

This paper introduces an algebraic cryptanalysis of a random number generator (RNG) based on a chaotic circuit using two ring oscillators coupled by diodes. An attack system is proposed to discover the security weaknesses of the chaotic RNG. Convergence of the attack system is proved using master slave synchronization scheme where the only information available are the structure of the RNG and a scalar time series observed from the chaotic circuit. Simulation and numerical results verifying the feasibility of the attack system are given. The RNG does not fulfill Big Crush and Diehard statistical test suites, the previous and the next bit can be predicted, while the same output bit sequence of the RNG can be reproduced.