When embedding secret message into image by steganography with matrix encoding, there are still no effective methods to recover the stego key because it is difficult to statistically distinguish the stego coefficient sequences selected by true and false keys. Therefore, this paper proposes a method for recovering the stego key of a typical JPEG (Joint Photographic Experts Group) image steganography—F5 which composes of the check matrix and shuffling key. Firstly, the check matrix is recovered based on the embedding ratio estimated by quantitative steganalysis. The shuffling key is then recovered based on the distribution difference between the bit sequences extracted by the true and false shuffling keys. Additionally, the cardinality of the shuffling key space is significantly reduced by examining the extracted encoding parameter and message length. Experimental results show that the proposed method can recover the stego key accurately and efficiently, even when the existing Xu’s method fails for the high or very low embedding ratio.

中文翻译：

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具有矩阵编码的f5隐写术的隐身密钥恢复方法

当通过具有矩阵编码的隐写术将秘密消息嵌入图像中时，仍然没有有效的方法来恢复隐秘密钥，因为难以统计地区分由真和假密钥选择的隐秘系数序列。因此，本文提出了一种恢复典型的JPEG（联合图像专家组）图像隐写术-F5的隐秘密钥的方法，该方法由校验矩阵和混洗密钥组成。首先，根据定量隐写分析估计的嵌入率，恢复校验矩阵。然后基于由真和假混洗密钥提取的位序列之间的分布差异来恢复混洗密钥。另外，通过检查提取的编码参数和消息长度，显着降低了改组密钥空间的基数。实验结果表明，即使现有的徐氏方法由于嵌入率高或低而失败，该方法仍可以准确，有效地恢复隐秘密钥。