Difference map and its electronic circuit realization

"In this paper we study the dynamical behavior of the one-dimensional discrete-time system, the so-called iterated map. Namely, a bimodal quadratic map is introduced which is obtained as an amplification of the difference between well-known logistic and tent maps. Thus, it is denoted as the so-called difference map. The difference map exhibits a variety of behaviors according to the selection of the bifurcation parameter. The corresponding bifurcations are studied by numerical simulations and experimentally. The stability of the difference map is studied by means of Lyapunov exponent and is proved to be chaotic according to Devaney’s definition of chaos. Later on, a design of the electronic implementation of the difference map is presented. The difference map electronic circuit is built using operational amplifiers, resistors and an analog multiplier. It turns out that this electronic circuit presents fixed points, periodicity, chaos and intermittency that match with high accuracy to the corresponding values predicted theoretically.

Hyperchaotic encryption based on multi-scroll piecewise linear systems

"A hyperchaotic multi-scroll piecewise linear system in R4 is binarized to generate a pseudo-random sequence which encrypt a grayscale image via symmetric-key algorithm. The sequence is analyzed throughout statistical tests according to the National Institute of Standards and Technology (NIST) specifications. The scrolls of the system are the result of a switching law that changes between the saddle hyperbolic equilibria of piecewise linear systems with eigenvalues as follows: two negative real and one pair of complex conjugate eigenvalues with positive real part. Thus, the encryption quality is evaluated depending on the variation of the number of scrolls.