基于编码转移特性的信息隐藏掩密术掩密安全原则研究

Study on Steganographic Security in Information Hiding Based on Coding Transition Diagram

本文针对信息隐藏领域中的掩密术（STEGANOGRAPHY）的安全性问题，研究分析了（Christain Cachin等文献中）传统信息隐藏模型的局限性．结合数据冗余空间的掩密术安全性，提出掩密术的编码安全性的分析方法．该方法结合编码转移图和编码转移概率矩阵，能分析目前应用最广泛的基于替换原理的掩密编码方式的安全性，并用编码子空间重心、掩密编码重心和编码子空间偏心度来度量掩密术编码对掩密术安全性的影响，进而提出掩密术编码安全原则，证明满足安全原则的编码转移矩阵的存在性．最后基于该掩密术编码安全原则，提出了对用量化后DCT系数携带密信的掩密术改进方法．

Steganographic security is very important in information hiding. However,existing models of information hiding have many shortcomings in this field, informed by redundancy of data space, this paper proposed a new method, called Coding Transition Diagram （ CTD）, to evaluate the security of the coding model of steganography. The method, which combines coding model and transition matrix, measures the security of coding models using statistics in data space. Based on the method, we introduced four rules to improve the security of coding model and proofed the existence of the coding model which fulfills the four rules in DCT space.