Heterogeneous chaotic systems based cryptography

A new chaos based cryptosystem is proposed to transmit digital information signal by using the conventional synchronization approach with cascaded heterogeneous chaotic systems. In this scheme two heterogeneous chaotic circuits (hyperchaotic and chaotic) are used both at the transmitter and receiver modules. The hyperchaotic system is used to mask the information signal and to produce a plaintext signal. The chaotic system acts as an encrypter in the transmitter module. Similarly the receiver module consists a chaotic decrypter and a hyperchaotic system. A multishift cipher scheme is considered both at the encrypter and the decrypter for respective encrypting and decrypting the plaintext messages. An appropriate feedback loop is constructed in the response-module to acheive synchronization among the variables of the drive and response-modules. Simulation results are reported in which the quality of the recovered signal is higher and the encoding is potentially secure. The effect of perturbing factors like channel noise and nonidentity of parameters are also considered. (C) 2000 Elsevier Science B.V. All rights reserved.