OPTICAL IMPLEMENTATION OF THE STREAM CIPHER BASED ON THE IRREVERSIBLECELLULAR-AUTOMATA ALGORITHM

A hybrid optical scheme for efficient hardware implementation of the o ne-dimensional, three-neighborhood binary cellular automata rule a(i)' = a(i-1) XOR (a(i) OR a(i+1))-based stream cipher is proposed. The sy stem makes full use of the parallel, space-invariant, cascadable, and modular structure of the algorithm and is simple, robust, and compact. The number of cellular automata arrays can be as large as the number of pixels on the spatial light modulator, which results in an increase in speed (number of bits operated in parallel) and security (key leng th). The system can be made fully optical with the use of an optically addressable spatial light modulator for the input plane and for the n onlinear threshold element. (C) 1997 Optical Society of America.