Efficient and cryptographically secure pseudorandom number generators based on chains of hybrid cellular automata maps

Abstract

In this paper we consider several solutions for designing cryptographically good pseudo random number generators (PRNG) with low complexity implementations. Our solutions are based on hybrid cellular automata (HCA) maps. The first solution (ensuring maximal throughput) is based on creating chains of HCA maps, i.e. the nonlinear map is changed dynamically being controlled by another HCA map within a chain. The second solution is simpler but somehow reduces the throughput and it is based on the down-sampling of a single HCA output with a factor d. It is shown that both solutions pass all statistical tests of NIST.

An Application of Keystream Using Cellular Automata for Image Encryption in IoT

“…The security is lower if the sequence is iterated using a single CA rule [12]. To increase the chaos of the output keystream and improve the randomness, we process the iteration by multiple CA rules.…”

“…If x increases when y increases, the correlation coefficient is closer to 1, and if x decreases when y increases, the correlation coefficient is closer to -1. A correlation coefficient of 0 means that there is no linear correlation between the two variables x and y. Equations (9)(10)(11)(12)(13) show the algorithm of the correlation coefficient r xy , where r xy represents the covariance of two variables x and y, cov(x,y), divided by the product of their standard deviations D(x) and D(y), and N is the total number of pixels.…”

“…The proposed keystream generator is based on iteration. The output data of one iteration are the input for the keystream generator for the next iteration of the CA [12][13]. In this paper, we introduce the sliding-window concept to strengthen the keystream generator in terms of security.…”