为了进一步提高自适应隐写算法的安全性，本文引进图像分块的思想，改写了原J-UNWARD算法的失真函数，变加性失真函数为非加性失真函数。载体图像被分为4个子块，分别计算每个子块的纹理复杂度以嵌入总量不变为约束条件，优先嵌入复杂度较大的块，每嵌入一块完成后重新计算失真函数，根据复杂度大小动态调整每个子块的嵌入量。利用STC（syndrome trelliscodes）编码将秘密信息自适应地嵌入到纹理区域，最后采用DCTR和ccJRM两种隐写分析技术进行检测分析。实验结果表明：在相同容量下，改进算法能显著提高算法的抗隐写分析能力。
In order to further improve the security of adaptive steganography algorithms, this article introduces the idea of image blocking, rewrites the distortion function of the original J-UNIWARD algorithm, and changes additive distortion functions to non-additive distortion functions. The implementation process of the algorithm is as follows: The carrier image to be processed is divided into four sub-blocks, and the texture complexity of each sub-block is calculated separately, under the constraint of keeping total embedding amount unchanged. The more complex blocks are preferentially chosen to be embedded. By recalculating the distortion function after each block-embedding, the embedding amount is dynamically adjusted according to the complexity. Then the secret information is adaptively embed into the texture area by STC (syndrome trelliscodes) encoding. Finally, detection performance is analyzed by using DCTR and ccJRM steganalysis techniques. Experimental results show that under the same capacity, the proposed algorithm can significantly improve the anti-stealth analysis ability of the algorithm.
[1] Zhang Q, Liu Y, Nan Y, et al. Classification algorithm of JSteg and F5 Stego-images based on histogram difference[J]. Energy Procedia, 2011, 13:8759-8766.
[2] Westfeld A. F5-a steganographic algorithm[C]//International Workshop on Information Hiding. Springer, Berlin, Heidelberg, 2001.
[3] Huang J W, Shi Y Q. Embedding gray level images[C]//ISCAS 2001. The 2001 IEEE International Symposium on Circuits and Systems. IEEE, 2001.
[4] Fridrich J. Statistically undetectable JPEG steganography:dead ends challenges, and opportunities[C]//Workshop on Multimedia & Security. DBLP, 2007.
[5] Sachnev V, Kim H J. An improved matrix encoding scheme for JPEG steganography[C]//International Conference on Digital-forensics & Watermarking. Springer, Berlin, Heidelberg, 2011.
[6] Fridrich J, Goljan M, Lisonek P. Writing on wet paper[J]. IEEE Transactions on Signal Processing, 2005, 53(10):3932-3935.
[7] Filler, T, Judas, J, Fridrich J. Minimizing additive distortion in steganography using syndrome-trellis codes[J]. IEEE Transactions on Information Forensics & Security, 2011, 6(3):920-935.
[8] Fridrich J, Kodovský J. Multivariate gaussian model for designing additive distortion for steganography[C]//IEEE International Conference on Acoustics. IEEE, 2013.
[9] Fridrich J J, Goljan M, Soukal D. Perturbed quantization steganography with wet paper codes[C]//Proceedings of the 6th workshop on Multimedia & Security. Magdeburg, Germany, 2004.
[10] Huang F J, Huang J W, Shi Y Q. New channel selection rule for JPEG steganography[J]. IEEE Transactions on Information Forensics & Security, 2012, 7(4):1181-1191.
[11] Guo L J, Ni J Q, Shi Y Q. Uniform embedding for efficient JPEG steganography[J]. IEEE Transactions on Information Forensics & Security, 2014, 9(5):814-825.
[12] Guo L J, Ni J Q, Shi Y Q. An efficient JPEG steganographic scheme using uniform embedding[C]//IEEE International Workshop on Information Forensics and Security, Tenerife, 2012:169-174.
[13] Guo L J, Ni J, Su W, et al. Using statistical image model for JPEG steganography:uniform embedding revisited[J]. IEEE Transactions on Information Forensics and Security, 2015, 10(12):2669-2680.
[14] 潘琳, 钱振兴, 张新鹏. 基于构造纹理图像的数字隐写[J]. 应用科学学报, 2016, 34(5):625-632. Pan L, Qian Z X, Zhang X P. Steganography by constructing texture images[J]. Journal of Applied Sciences, 2016, 34(5):625-632. (in Chinese)
[15] Oosterwijk J J, Skoric B, Doumen J. Optimal suspicion functions for Tardos traitor tracing schemes[C]//ACM Workshop on Information Hiding & Multimedia Security. ACM, 2013:19.
