基于二维Logistic映射和二次剩余的图像加密算法

针对公共网络中数字图像的安全传播问题，提出了一种基于二维Logistic混沌映射和二次剩余的图像加密算法.该加密算法利用二维Logistic映射的优良随机性，对明文图像进行2次置乱，极大地改变了图像像素位置.然后把置乱图像展开成二进制序列，按照8位一组进行分块，再利用二次剩余密码体制对每个分块进行加密，有效地改变了明文图像的信息.最后，对该算法进行直方图分析、信息熵分析、密钥敏感性分析以及明文图像和密文图像的相关系数分析等仿真实验.实验表明该算法能抵抗统计攻击、信息熵攻击，是一种较安全的图像通信方式.

A Novel Image Encryption Scheme with 2D Logistic Map and Quadratic Residue

Considering the importance of image transmission in the public net， a new image encryption algorithm was proposed based on the 2D Logistic chaos and quadratic residue. Firstly， the original image was shuffled twice with the 2D Logistic chaos map， and the positions of the original image were changed sufficiently. Then， the shuffled image was turned into a binary sequence， and every 8 bits were called a block. For each block， quadratic residue was applied to encrypt the block， then， the encrypted binary sequence was turned into the encrypted image. Therefore， the statistical information of plain image was changed drastically by the proposed scheme. The proposed image scheme was tested by various types of experiment and security analyses such as histogram analysis， information entropy， key sensitivity and correlation coefficient analysis. All these analyses demonstrated that the proposed scheme can resist statistical attack， information entropy attack， and it is very proper for secure image communication.