Color image cryptosystem using chaotic maps

Abstract

Image encryption is somehow different from text encryption due to some inherent features of image such as bulk data capacity and high correlation among pixels, which are generally difficult to handle by traditional methods. The exceptionally desirable properties of the chaotic maps such as sensitivity to initial conditions and random-like behavior have attracted the attention of cryptographers to develop new encryption algorithms. This paper proposes a new symmetric image cipher based on the widely used confusion-diffusion architecture which utilizes the chaotic 2D Standard map and 1D Logistic map. It is specifically designed for the color images, which are 3D arrays of data streams. We prefer chaotic Standard map to Baker and Cat maps since the key space of the chaotic Standard map is large enough as compared to the Baker and Cat maps, which makes the brute-force attack infeasible. The initial conditions and system parameters of the chaotic maps constitute the secret key of the algorithm. To further enhance the security, the control parameters used in the confusion stage and the keystream employed for diffusion stage are distinct in different rounds and related to the plain-image. These control parameters are generated by a Tent map. For getting higher security and higher complexity, the current scheme employs two kinds of diffusion processes namely the horizontal and vertical diffusions which are completed by mixing the properties of horizontally and vertically adjacent pixels using a Logistic map, respectively. The results of several experiments, including the most important ones like key space analysis, key sensitivity test, statistical analysis, and visual test by histograms of encrypted images, the correlation coefficients of adjacent pixels, and differential analysis, demonstrate the satisfactory security and efficiency of the proposed image encryption scheme for real-time image encryption and transmission.