Abstract: This essay has brought forward one kind of the image compound encryption algorithm which is based on chaotic mapping and gray substitution，and have adopted one-dimension logistic chaotic sequences to confuse the image ranks respectively，and has combined with gray substitution.The algorithm possesses high security.An new DCT-based information-hiding algorithm is proposed by making use of Human Visional System’s（HVS） character，and choosing the appropriate modulus after image frequency region varies，adjusting it’s odd-even mantissa，to reach the purpose，and to expand it to multi-level information-hiding technology based on other varying region，the experiments testify it has possessed the merit of high capacity，strong robust and drawing blindly.

Key words: chaos, image encryption, information hiding, drawing blindly

摘要： 提出一种基于混沌映射和灰度替换的图像复合置乱算法，算法采用了一维logistic混沌序列对图像的行列分别置乱，并与灰度替换相结合，实验表明其具有较高的安全性。利用人眼视觉系统（HVS）的特性，提出一种新的基于DCT的信息隐藏算法，通过选取频域变换后的适当系数，调整其尾数的奇偶，达到嵌入秘密信息的目的，并将其扩展为基于其他变换域的多级信息隐藏技术，实验证明其具有隐藏量大、鲁棒性较强、盲提取的优点。

关键词: 混沌, 图像置乱, 信息隐藏, 盲提取