基于分散式块相关水印的图像认证技术

提出了一种新的分散式块相关水印技术用于图像的完整性认证和篡改定位.分散式块相关水印技术兼具了水印的高安全性和高定位精度，克服了传统块相关水印技术定位精度低等问题.将原始图像划分为互不重叠的图像块，对每一个图像块进行独立的水印生成.将图像块特征值映射为混沌系统的初值，经过多次混沌迭代得到图像块水印.另外，利用混沌序列排序法构成了图像块之间的一对多关系，形成分散式块相关结构，再将该图像块的水印嵌入到对应图像块的最低有效位中，完成水印的嵌入.实验结果表明，分散式块相关水印技术能够有效地抵抗矢量量化攻击，并对图像的篡改进行精确的定位.

Image Authentication Method Based on Divergent Block-Dependent Watermarking

A new divergent block-dependent watermarking method is proposed to authenticate the integrity of the image and localize the image tampers. The divergent block-dependent watermarking method is prior to conventional block-dependent watermarking method with improved security and localization accuracy. the original image is firstly divided into non-overlapping blocks, and then the block watermark is independently generated. the characteristics of the image block is mapped into the initial value of a chaotic map, and the block watermark is generated by iterating the chaotic map from the initial value. In the meantime, a block related to several blocks is made by sorting chaotic sequences to form the divergent block-dependent structure. Then the block watermark is inserted into the least significant bits of the related blocks to obtain the watermarked image. The experiments show that the proposed divergent block-dependent watermarking method can resist to the counterfeiting attack, and localize the tampers correctly and accurately.