A New Fast Color Image Encryption Scheme Using Chen Chaotic System

Recently, a number of chaos-based image ciphers with permutation-substitution structure have been suggested. Generally, the permutation and substitution are considered as two independent procedures, and individual chaotic maps or systems are iterated and quantified to produce the keystreams for the two stages. In this paper, we suggest a fast color image encryption scheme with both permutation and substitution keystreams quantified from a sequence extracted from the orbit of chaotic Chen's system. As the total number of iterations is reduced by half, the computational efficiency is improved. To confuse the relationship between the ciphertext and the secret key, the positions of subpixels in each color channel are scrambled across the entire color space using a pixel-swapping strategy, which can avoid the periodicity problem encountered by the discretized version of area-preserving chaotic maps. Experimental results demonstrate that the proposed scheme has a satisfactory level of security and outperforms the conventional scheme in term of computational efficiency.