关键词: Logistic映射, Lorenz系统, 置乱, 灰度变换, 安全性分析

Abstract: An image encryption scheme based on composite chaotic system was proposed. The encryption system used the one-dimensional Logistic chaotic maping and the three-dimensional Lorenz system to produce chaotic sequences, and chose different ways to deal with scrambling transformation and gray transformation for each pixel according to the structural characteristics of the image itself. The security analysis shows that the proposed image encryption scheme provides higher efficiency and larger key space, and it is very sensitive to the key and the plaintext. It is characterized by excellent diffusion and confusion properties, which can resist the known-plaintext attacks and chosen-plaintext attacks.

Key words: Logistic mapping, Lorenz system, scrambling transformation, gray transformation, security analysis