A novel modelled true random binary number generator for key stream generation in cryptographic applications

Abstract

In this paper, a modified double scroll chaotic attractor circuit, which is employed as a true random binary number generator (TRBNG), is presented for use as a key source in cryptographic applications. The double scroll attractor is modelled on Chuapsilas circuit for nonlinear operation leading to chaotic behaviour. Previous reported versions of this circuit used von Neumannpsilas deskewing algorithm and optimal voltage threshold settings for random number generation. The binary sequence obtained from this structure passed the FIPS set of tests, but this type of generator will not pass the NIST Test Suite for true randomness owing to some residual structural correlation in the output sequence which is essential for consideration as a cryptographic module in the Advanced Encryption Standard (AES). This generator has been modified, as presented here, with the deskewing algorithm replaced by a pseudo random binary sequence generator (PRBSG) topology where the output correlated data from the TRBG is scrambled with the PRBS to yield a true random binary source for key stream generation. This proposed generator topology will pass the complete NIST and Diehard Test Suites. The modified chaotic circuit has been modelled in PSpice, and a state space formulation of this circuit has also been obtained and implemented in Matlab/Simulink. The randomness attributes of the modified generator, obtained from both models via PSpice and Matlab/Simulink, using the PRBSG decorrelator were tested by the well known NIST Tests Suite for statistical validation. Output binary streams from proposed modified generator, consisting of 1000000 digits each, were examined for randomness using the NIST Test Suite with all tests successfully passed for both PSpice and state-space models of chaotic circuit implementation.