Design and Analyses of Efficient Chaotic Generators for Crypto-systems

In this paper, we design and implement under Matlab/Simulink some efficient digital chaotic generators for data encryption/decryption process. Some of these generators (logistic, PWLCM, Frey) are known, the others xcos(x), xexp[cos(x)], 2-D Tmap) are proposed. A number of designed generators contain cascaded layer to improve the statistical properties of the generated sequences. We introduce and demonstrate the importance of the perturbing orbit technique to avoid the dynamical degradation caused by the 2N-dimensional finite state space. This technique increases also the orbit cycle length. Finally, to quantify the security level of the proposed generators, we analyze their global dynamical properties using system and signal processing tools (Lyapunov exponents, bifurcation diagrams, distribution, pseudo phase space, autonotcorrelation, cross correlation, NIST tests ldquoNational Institute of Standards and Technology ldquo). Experimental and theoretical analyses show that the proposed generators have good cryptographic properties.