【作者】 黄春梅；

【导师】 马光胜；

【作者基本信息】 哈尔滨工程大学 ， 计算机应用技术， 2009， 硕士

【摘要】 随着因特网的迅猛发展和多媒体技术的广泛应用,信息隐藏技术已经成为信息安全领域一个新的研究热点。目前的研究主要是利用图像、声音、视频等载体来进行信息隐藏。本文首先介绍了信息隐藏的基本概念和理论,如其特性、分类、应用等,然后就基于文本的信息隐藏技术和基于图像的信息隐藏技术做了相关研究。(1)基于文本的信息隐藏算法的改进本文在深入研究目前文本数字水印技术、分析了文本信息隐藏算法缺陷的基础上,改进了一种基于文本的零水印算法。该算法首先通过文本中的标点符号来确定文本特征,然后通过将加密后的水印信息和加密后的文本特征相异或,将水印信息加到宿主信息中。实验证明该算法具有完好的隐蔽性和较强的鲁棒性。但是该方法,只能应用于信息的隐秘性,不能应用于版权保护,还有待改进。(2)基于图像的信息隐藏算法的改进本文根据对离散余弦变换(DCT)、离散小波变换(DWT)理论的分析研究,提出了变换域内实现数字图像水印嵌入的改进算法。在深入理解数字图像小波变换后系数具有相关性特点的基础上,对变换后的数字图像系数作DCT变换,再嵌入数字水印,这使得算法兼有了两种变换的特点,增强了水印算法的稳健性。本文对所提出的算法进行了不可见性和鲁棒性实验。实验结果表明,算法具有很好的不可见性,对常见的图像处理操作具有较好的鲁棒性。本文最后对信息隐藏技术的发展作了展望。更多还原

【Abstract】 With dramatic advance of Internet and wide application of the multimedia technology, information-hiding techniques have become a new hot topic in the domain of the information security. Today’s information hiding techniques mainly use image,audio and video as cover objects. In the thesis, firstly we introduce the basic concepts and theoretics of information hiding technologies and digital watermarking, such as charachteristics, classification and application and so on, then the information hiding techniques based on text and on image are discussed in detail in this paper.(1) Improvement on information hiding algorithms based on textWe analyze the information hiding techniques based on text in detail and give a survey of today’s polular algorithms of text document information hiding and their advantages and shortcomings. In this algorithm the text characters are firstly determined by punctuations, and then by XOR the encrypted charcters and the encrypted watermarking information, the watermark is embedded into the text. The experimental results show that the algorithm has complete hiding effectiveness and strong robustness. However, the method can only be applied to information hiding, not be used for copyright protection, yet to be improved.(2) Improvement on information hiding algorithms based on imageA digital watermark embedding algorithms in transform domain is presented, which is based on analysis and research of DCT, DWT and Neural Network. With the coefficients after Discrete Cosine Transform(DWT) of the digital image having correlations, we firstly consider making another Discrete Cosine Transform(DCT) of them, and then embedding digital watermark. The algorithm has the characteristics of both DWT and DCT, so enhances the robustness. Finally, in order to verify the impercettibility and robustness of the algorithms proplsed in this paper, a lot of experiments have been done. The experimental results show that the algorithms has good imperceptibility and very strong ability against geometry attack and common image processing operations. At last a conclusion and prospect of this paper have been done.更多还原