说明：  数字图像在现代生活中的应用日益广泛，在一些领域中 须关注其安全问题，例如，军事、医疗和商业图片通常需 进行保密传送。目前最佳的保密手段是采用加密算法。但 于图像的数据量通常较大，因此图像加密时间较长。研究 提出了各种图像加密技术，利用图像的各种性质进行加密 而提高加密速度[1]。现有图像加密技术可以分为空域图像 密技术、变换域图像加密技术和压缩编码图像加密技术。 文研究的图像加密算法属于空域图像加密技术。在文献[2] 出的自适应图像加密算法的基础上，本文给出一种改进的
(Existing self-adaptive image encryption algorithm is resistant to known plaintext attacks and with high speed of single round encryption, but its security and speed of whole round encryption is low. This paper proposes a new fast image encryption algorithm based on self-adaptive permutation. This algorithm insures the simpleness and high efficiency of encryption operation, and changes the pixel distribution of encrypted image compared with that of original image. Experimental results show that this algorithm has better performance than other kindred algorithms. 【Key words】image encryption self-adaptive permutation cryptography)