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Wen C.-C.,University of Science and Technology Beijing | Wang Q.,University of Science and Technology Beijing | Huang F.-M.,Chinese Academy of Sciences | Yuan Z.-S.,Air Force Jing Chang Office | Tao C.-S.,Peoples Liberation Army 218 Factory Office
Tongxin Xuebao/Journal on Communications | Year: 2012

On the basis of three-dimensional affine transformation in limited integer domain and composed chaos, a novel digital image encryption algorithm was proposed. Firstly, it scrambled pixels' position and confused pixels' value according to corresponding coordination. Secondly, it took a series of nonlinear diffusion, substitution and re-diffusion. In the process of substitution, it introduced pixels' value to perturb multiple chaos systems that were coupled together for self-adaptive encryption. The algorithm proceeded the above two steps for 3 times to defend chosen plaintext attack, and had huge key space to defend violent attack. The scrambling function in it was compatible with images at any ratio of length to width without any preprocessing; the constructed whole chaos system which had a simple form was designed modularly, and could be realized parallel conveniently. Source


Wen C.,University of Science and Technology Beijing | Wang Q.,University of Science and Technology Beijing | Huang F.,Peking Union Medical College | Liu X.,Air Force Jing Chang Office | Chen X.,Office of Academy
Jisuanji Fuzhu Sheji Yu Tuxingxue Xuebao/Journal of Computer-Aided Design and Computer Graphics | Year: 2012

Based on the compound chaos and affine transformation in finite integer domain, an encryption algorithm is proposed to embed into the compression of JPEG image. Firstly, the blocks of 8×8 pixels of R, G and B components are scrambled globally in space domain to disarrange the combination relation among three components before the precedence of normal JPEG compression. Secondly, the frequency domain's DC coefficients of brightness and color components are scrambled respectively after quantization, and their values are mixed according to the corresponding coordination. Lastly, the compound chaos system is perturbed to substitute for the DC coefficients self-adaptively. Our algorithm is designed modularly with huge key space and high security. The experiments showed that the algorithm produce results with high visual quality with strong sensitivity, and could generate the ciphertext with almost the same size as that of the directly compressed image. Source


Wen C.,University of Science and Technology Beijing | Wang Q.,University of Science and Technology Beijing | Liu X.,Air Force Jing Chang Office | Huang F.,Peking Union Medical College | Yuan Z.,Air Force Jing Chang Office
Jisuanji Yanjiu yu Fazhan/Computer Research and Development | Year: 2013

With the popular application of multimedia, the security of digital image becomes more and more important. According to the feature of digital image and on the basis of three-dimension affine transformation and chaos, a novel spatial domain encryption algorithm is proposed. Firstly, it scrambles pixel position and confuses pixel value according to the corresponding coordination. Secondly, it takes a series of nonlinear diffusion and substitution in turn for all lines. The algorithm proceeds with the above two steps for at least 3 times, and it can be conveniently converted to the frequency domain algorithm while replacing the processed data in the spatial domain with quantized coefficients in the frequency domain. In the process of substitution, pixel value is introduced to perturb multiple chaos systems that are coupled together for self-adaptive encryption. In the encryption process, the scrambling parameters are generated by chaos systems automatically, and the scrambling function is compatible with images at any ratio of length to width without any preprocessing. Theoretical analysis shows that the algorithm has huge key space to defend against violent attack, the mapping relation between the plaintext and the ciphertext is complex enough to resist chosen plaintext attack efficiently, and the algorithm using simple chaos systems is designed modularly in order to be realized parallelly conveniently. Experimental results show that the algorithm takes good encryption result, gets strong sensitivity, conforms to confusion and diffusion principles in cryptography, and achieves high security. Source

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