The paper presented a method of digital image scrambling based on binary tree generated by chaotic sequences. First,
conservative chaos system is iterated to produce chaotic sequences after given initial value and parameters. Then, binary
tree is generated by chaotic sequences according to certain rule. At last, the order received by inorder traversing the
binary tree is used to transform order of pixels. In this method of digital image scrambling the secret key is initial value
and parameters. This method is flexible to use because the secret key is separated from algorithms. It remedies
inadequateness of flexibility in other algorithms merely adopting fixed binary tree. Some evaluation indexes show that
the method has good effect of image scrambling.
In this paper, the properties of the gray level mixing function in two-dimensional chaotic map image encryption are analyzed. We also discuss the necessity of introducing parameters and the methods how to present diffusion mechanism and interfuse a pseudo-random number sequence in the gray level mixing function. We proposed a new kind of gray level mixing function which not only have diffusion mechanism but also have random variable . It is shown in experiment that this method has good performance.