对随机LSB隐写术的选择密钥提取攻击

Chosen-key extracting attack to random LSB steganography

提出一种针对随机LSB隐写术的选择密钥提取攻击方法。对一类伪随机置换隐写术建立有向圈模型,证明了有向圈模型中存在大量等价密钥和相邻密钥,并给出计算等价密钥量的方法。利用等价密钥和相邻密钥的性质,结合突变点检测法,提出一种基于选择密钥的提取攻击算法,其计算复杂度低于Fridrich方法。理论分析和实验结果均表明,即使对消息嵌入率估计存在较大误差,该算法仍具有较强稳健性。

A chosen-key extracting attack based on random LSB steganography was proposed.By constructing an orient ring model for a sort of pseudo-random steganography algorithms,it proved that there are many equivalent keys and neighboring keys in the model,and then proposed a method to calculate the number of equivalent keys.With the charac-ter of equivalent keys,neighboring keys and outlier detection method,the proposed scheme achieved lower computational complexity than the method proposed by Fridrich.Both academic results and experimental results indicated that the algorithm was reliable even with rather big error in estimating the embedding rate.