Encryption of Analog and Digital signals through Synchronized Chaotic Systems

Chaos is characterized by aperiodic, wideband, random-like, and ergodicity. Chaotic secure communication has become one of the hot topics in nonlinear dynamics since the early 1990s exploiting the technique of chaos synchronization. As distinguished by the type of information being carried, chaos-based communication systems can be categorized into analogy and digital, including four popular techniques such as Chaos Masking, Chaos Shift Keying, Chaos Modulation, and Chaos Spreading Spectrum. In this chapter, the principles of these schemes and their modifications are analyzed by theoretical analysis as well as dynamic simulation. In addition, chaos-based cryptography is a new approach to encrypt information. After analyzing the performances of chaotic sequence and designing an effective chaotic sequence generator, the authors briefly presented the principle of two classes of chaotic encryption schemes, chaotic sequence encryption and chaotic data stream encryption.