基于K-L差异的隐密术安全性理论研究

The Study of Security in Steganography Based on K-L Divergence

隐密术安全性理论研究一直是被广泛关注的研究重点和难点。该文通过对K-L差异的回顾及隐密术安全性的定性分析,指出Cachin给出的安全性定义缺乏一般性。同时注意到除概率分布的差异外,隐密信息的样本量和状态集合的势对隐密信息的安全性也有重要影响。结合对隐密信息安全性的定性分析,给出了一个基于K-L差异及假设检验的隐密术安全性定义,并推导出修改率对于隐密术安全性的影响。最后结合现有的隐密算法和隐密分析算法设计了一组对比试验,以验证该文理论分析的有效性。

This paper presents a universality method for measure of security in steganography. According to the definition of K-L divergence and the properties of security in steganography, some limitations in Cachin＇s definition of security are shown in the beginning. Besides the divergence of probability distributions between stego and cover, the sample size and the cardinality of the state set of random variable have great effect on security in steganography Based on K-L divergence and hypothesis testing, an amended measure of security and a useful illation are presented The result of examination can prove that the new measure of security is reasonable.