A New chaos-based image encryption system

International audienceDuring the last decade, a variety of chaos-based cryptosystems has been introduced toprotect the content of the transmitted images. In this paper, we propose a new fast, simple, and robustchaos-based cryptosystem structure and we analyze its performances. The cryptosystem uses adiffusion layer followed by a bit-permutation layer, instead of byte-permutation, to shuffle thepositions of the image pixels. Moreover, the permutation layer is achieved by a new proposedformulation of the 2D cat map that allows an efficient implementation, measured by the timecomplexity, in terms of arithmetic and logic operations, and also, in terms of clock cycles, of the keydependentpermutation process in comparison with the standard one. Hence, it provides a very fastdiffusion process to spread the influence of a single bit over the others. The new cryptosystem includesa robust and uniform chaotic pseudo-random generator (a very simplified version of a generatorpublished in our patent) to change the control parameters in each round of the encryption/decryptionprocesses. The generator is highly nonlinear and produces robust sequences of discrete values havingvery long orbits. The proposed cryptosystem is defined on finite numbers, and its speed is faster thanmany chaos-based cryptosystems, while having a very high security level. The security analysis and theobtained simulation results show that the proposed cryptosystem is resistant to various types ofattacks and it is efficient for hardware and software implementation