1. INTRODUCTION
Over the past decade, there has been tremendous interest in studying the behavior of chaotic systems. They are characterized by sensitive dependence on initial conditions, similarity to random behavior, and continuous broad-band power spectrum. Chaos has potential applications in several functional blocks of a digital communication system: compression, encryption and modulation. The possibility for self-synchronization of chaotic oscillations [1] has sparkled an avalanche of works on application of chaos in cryptography. An attempt only to mention all related papers on chaos and cryptography in this short communication, will result in prohibitively long list, and therefore, we refer the reader to some recent work [2].