Secure color image encryption algorithm based on chaotic signals and its FPGA realization

Abstract

SummaryIn this paper, we designed a three‐dimensional chaotic system (3D chaotic system). The continuous‐time chaotic system had already been transformed into discrete‐time (DT) chaotic system by Euler method. The phase portrait of DT chaotic system had been implemented on an oscilloscope via Altera field programmable gate array (FPGA) DE2‐115. A cryptographic system of RGB image security for 3D chaotic system was proposed. There are three features in the encryption system. First, we use the information of plaintext image to produce the initial conditions of chaotic system. Second, the image of the permutation process shuffles the position of pixels in the plaintext image among RGB channels separately. Third, in the diffusion process, the pixels information in the shuffled image had been concealed by the XOR operation. The 3D chaotic encryption system had been also implemented on Altera DE2‐115. Then, the cipher image can be obtained through the FPGA and simulated the image by Matlab code. In the security analysis, such as histogram analysis, correlation coefficient analysis, information entropy analysis, differential attack analysis (NPCR and UACI) have been performed in this paper. Experimental results show that the proposed algorithm has better security in comparison with other algorithms.