Journal of Signal and Information Processing, 2011, 2, 238-244 doi:10.4236/jsip.2011.23033 Published Online August 2011 (http://www.SciRP.org/journal/jsip) Copyright © 2011 SciRes. JSIP Image Encryption Based on the General Approach for Multiple Chaotic Systems Qais H. Alsafasfeh, Aouda A. Arfoa Electrical Engineering Department, Tafila Technical University, Tafila, Jordan. Email: qsafasfeh@ttu.edu.jo, aouda@ttu.edu.jo Received April 10 th , 2011; revised July 5 th , 2011; accepted July 13 th , 2011. ABSTRACT In the recent years, researchers developed image encryption methods based on chaotic systems. This paper proposed new image encryption technique based on new chaotic system by adding two chaotic systems: the Lorenz chaotic system and the Rössler chaotic system. The main advantage of this technique is stronger security, as is shown in the encryption tests. Keywords: Lorenz Equations, Rossler Systems, Image Encryption, Chaos 1. Introduction Recent researches of nonlinear dynamical systems have been increasingly based on Chaos [1]. Image encryption schemes have been increasingly studied to meet the de- mand for real-time secure image transmission over pri- vate or public networks. Conventional image encryption algorithm such as data encryption standard (DES), is not suitable for image encryption because of the special storage characteristics of an image [2] and weakness of low-level efficiency when the image is large [3].The chaos-based encryption has suggested a new and efficient way to deal with the intractable problem of fast and highly secure, image encryption. Chaotic systems have many important properties, such as the sensitive dependence on initial conditions and sys- tem parameters, the density of the set of all periodic points and topological transitivity, etc. Most properties are related to some requirements such as mixing and dif- fusion in the sense of cryptography [4]. Matthews pro- posed a chaotic encryption algorithm in 1989 [5], since then, increasing researches of image encryption technol- ogy are based on chaotic systems [4,6-12]. These meth- ods have high-level efficiency but also weakness, such as small key space and weak security and complexity to overcome these drawbacks. This paper proposes a image encryption scheme based on combining two chaotic sys- tems (Lorenz and Rosslere) and compares the results with the other techniques. The paper is organized as fol- lows. Section 2 discusses the proposed scheme. Section 3 presents experimental results. Section 4 to Section 7 dis- cuss and examine the new scheme by applying statistical tests test also the security of the chaotic encryption is discussed. Conclusions are drawn in Section 8. 1.1. Lorenz Chaotic System The Lorenz equations are a fairly simple model in which to study chaos.   x y x y rx y xz z xy z                  (1) The arbitrary parameters  , r and b > 0 and for this example are  = 10, r = 28, b = 8/3. This system of differential equations is then solved numerically using Matlab’s ode 45 Runge Kutta routine. The results are plotted in Figure 1 [12]. 1.2. Rossler Chaotic System A system of three differential equations has a simpler strange attractor than Lorenz’s. That the Rossler system has only one quadratic nonlinear xz numerical integra- tion shows this system has a strange attractor for a = b= 0.2, c = 5.7 as shown in Figure 2 [12].   x y z y x ay z b zx c                (2) 2. The Proposed Scheme First, most researchers used chaotic image encryption