A symmetric image cryptosystem based on Chen´s chaotic system

Recently, the increasing demand for on-line image transmission over public networks has raised a lot of interest on chaos-based image encryption. For most existing schemes, the key stream used for diffusion is solely determined by the key, which favors chosen plaintext attack. To address this problem, this paper proposes a plaintext related diffusion scheme using Chen´s chaotic system. In diffusion stage, the state variables of Chen´s chaotic system are selected according to the plain pixel. As a result, the quantified key stream is related not only to the key but also to the plain image, which effectively improves the ability against chosen plaintext attack. Moreover, compared with 1D chaotic maps that commonly used in existing image ciphers, the Chen´s chaotic system has more complicated dynamical property and number of state variables, which further enhance the security of the cryptosystem. Thorough security analysis is carried out with detailed analysis, demonstrating the satisfactory security of the proposed scheme.