Cryptography based upon Cellular Automata

New results concerning application of cellular automata (CAs) to secret key cryptography is described in this paper. One dimensional nonuniform CAs are considered for generating pseudorandom number sequences used in a secret key cryptographic system. The quality of PNSs highly depends on set of applied CA rules. The search of rules relies on an evolutionary technique called cellular programming. Different rule sizes are considered. As the result of collective behavior of discovered set of CA rules very high quality PNSs are generated. Indeed the quality of PNSs outerforms the quality of known one dimensional CA-based PNS generators used for secret key cryptography. The extended set of CA rules proposed in this article makes the cryptography system much more resistant on attacks.