关键词: 混沌映射, 图像加密, 位置置乱, 像素位, 分段非线性映射

Abstract: In order to effectively improve the image encryption effect and safety, based on studying image encryption algorithm based on chaotic systems and bit operations, an improved algorithm of digital image encryption algorithm was proposed. Firstly, Logistic map was used to generate chaotic sequences, constructing row and column vector to scramble pixel position by the proposed algorithm. Secondly, another piecewise nonlinear Logistic sequence was applied to construct gray scale scrambling amplification factor to scramble the image gray scale, meanwhile the two processes were iteratively done . The mentioned algorithm made not only the key space increase and gray histogram uniform, but also the pixel correlation weaker and the operation speed faster than traditional algorithms. The experimental results show that the improved algorithm has good encryption efficacy and safety.

Key words: chaotic map, image encryption, position scrambling, pixel bit, piecewise nonlinear mapping