—种基于Baker映射与时空混沌的图像加密算法

分析了Baker映射在图像加密中的局限性,在此基础上提出改进措施,即基于比特位的图像分块与置乱方法.将此改进方法与时空混沌相结合,提出了一种新的图像加密算法.在该算法中,时空混沌的状态值用于确定图像的分块规则和改变明文比特的值.利用密文反馈模型,确定时空混沌的迭代次数,动态生成时空混沌的状态序列,并通过时空混沌系统的迭代,扩大密文反馈的影响.因此,算法具有很好的混淆与扩散特性.仿真实验和对比分析均验证了该算法具有良好的安全性和应用前景.

Image encryption algorithm based on improved baker map and spatiotemporal chaos

The limitation of Baker map when it is involved in image encryption is analyzed. To remedy this limitation, the improvements used to partition and permute the image based on bit value are suggested. Moreover, combining with spatiotemporal chaos, a novel image encryption method is proposed. The rules of image partition and changing values of plaintext are determined by the status values of spatiotemporal chaotic system. In the proposed image encryption algorithm, the ciphertexts are feedback to determine the iterate time of spatiotemporal chaos and change the mode of generating sequence of spatiotemporal chaos. The effect of feedback is expanded by iterating the spatiotemporal chaotic system, which enhance the confusion and diffusion of the proposed algorithm. Finally, simulation experiments and comparative analysis show that the proposed algorithm has good performance in security and high potential to be applied to image security.