NOCAS : A Nonlinear Cellular Automata Based Stream Cipher

Abstract

LFSR and NFSR are the basic building blocks in almost all the state of the art stream ciphers like Trivium and Grain-128. However, a number of attacks are mounted on these type of ciphers. Cellular Automata (CA) has recently been chosen as a suitable structure for crypto-primitives. In this work, a stream cipher is presented based on hybrid CA. The stream cipher takes 128 bit key and 128 bit initialization vector (IV) as input. It is designed to produce $\mathrm{2^{128}}$ random keystream bits and initialization phase is made faster 4 times than that of Grain-128. We also analyze the cryptographic strength of this cipher. Finally, the proposed cipher is shown to be resistant against known existing attacks.

Keywords

• cellular automata
• stream cipher
• nmix
• hybrid nonlinear cellular automata
• [info.info-dm] computer science [cs]/discrete mathematics [cs.dm]
• [math.math-ds] mathematics [math]/dynamical systems [math.ds]
• [nlin.nlin-cg] nonlinear sciences [physics]/cellular automata and lattice gases [nlin.cg]
• [math.math-co] mathematics [math]/combinatorics [math.co]