Application of improved blocking algorithm in rectangle image encryption
改进的分块算法在矩形图像加密中的应用

In order to improve image encryption algorithm resistance ability to exaustive attack, statistical attack and differential attack, this paper put forward a modified block encryption algorithm based on chaos, and applied it to rectangle image encryption. This algorithm generated Logistic initial condition by block external keys and chaotic sequence iterately for strengthening the sensitivity of keys. It proposed three-direction dispersion combined with pixel value substitution algorithm to increase the resistance ability to differential attack obviously. Meanwhile, it used feedback mechanism to modify keys. The results show that it not only has higher scrambling degree than two-dimensional chaotic system of image encryption, but also resists exaustive attack, statistical attack and differential attack effectively.