Fuzzy Model Based Chaotic Cryptosystems

In this chapter, we address a fuzzy model based chaotic cryptosystem. For the crytosystem, the plaintext (message) is encrypted using the superincreasing sequence formed by chaotic signals at the drive system side. The resulting ciphertext is embedded to the output or state of the drive system and is sent to the response system end. The plaintext is retrieved via the synthesis approach for signal synchronization. We show that the chaotic synchronization problem can be solved using linear matrix inequalities. The advantages of this crytosystem are the systematic methodology of fuzzy model based design suitable for well-known Lure type discrete-time chaotic systems; flexibility in selection of chaotic signals for secure key generator; flexibility of masking the ciphertext using either the state or output; multiuser capabilities; and a time-varying superincreasing sequence. In light of the above advantages, the chaotic communication structure has a higher-level of security compared to traditional masking methods. In addition, numerical simulations and DSP-based experiments are carried out to verify the validity of theoretical results.