SECURE COMMUNICATION WITH CHAOTIC SYSTEMS OF DIFFERENCE-EQUATIONS

The paper presents chaotic systems of difference equations that can ef fectively encrypt information. Two classes of systems are presented: T he first one (Class 1) is optimized for secure communications over rel iable channels, while the second (Class 2) tolerates transmission nois e at the expense of reduced parameter space size. The nonlinearity of these systems is achieved by designing proper piecewise linear functio ns and by using module operations. The utilization of additional nonli near terms can improve the enciphering efficiency. The encrypting perf ormance of the algorithms is evaluated analytically and by simulation experiments. Also, the case of an imperfect transmission channel that inserts noise in the transmitted signal is addressed and the design is modified in order to offer reliable secure transmission over channels with very small Signal to Noise Ratios.