Abstract: In order to renew the image that is attacked by shear transformation, an extended digital image encryption algorithm was proposed based on chaotic sequences. This approach encrypt digital image by permuting on bitmap after pretreatment, and decryption pixels’ values of the image which is attacked by shear transformation is computed by using neighboring pixels’ values, it can protect the encryption image from shear transformation attack. A binary sequence nonlinear generating method based on chaotic system is also presented. The experimental results indicate the algorithm has a good efficiency and is safer.

Key words: chaotic system, image encryption, bitmap, shear transformation, cat map

摘要： 为了能对经过剪切变换攻击的加密图像进行有效恢复，给出了一种基于混沌序列的数字图像加密算法，该方法在预处理的基础上，基于数字图像灰度矩阵位平面进行置乱加密，在恢复过程中通过像素邻域灰度信息进行恢复，能够有效抵御针对加密图像的剪切变换攻击，同时给出了一种非线性的、应用高维混沌系统产生二值序列的方法。实验表明，该方法具有较好的效率和安全性。

关键词: 混沌系统, 图像加密, 位运算, 剪切变换, 猫映射