Extracting Attack to LSB Steganography in Spatial Domain
Wei Zhang · Chinese Journal of Computers · 2007
Many steganalysis techniques have been developed to detect the existence of hidden information. However, there are few approaches about how to extract the hidden information, i.e., extracting attack to steganography. For key-dependent steganography, extracting attack is equivalent to recovering the stego key. By combining detecting techniques in steganalysis and correlation attack in cryptanalysis, the authors propose a new method to recover the stego key of LSB steganography in spatial domain of images. Theoretic analysis is made for this method, which establishes that its complexity is mainly determined by the number of samples and the attack will fail when the embedding rate r tends to 0 or 1. The authors introduce an estimator for the minimum number of samples n based on a mixture Gaussian model. The experiments on the stego software Hide and Seek 4.1 show that the proposed method can recover the stego key and extract the hidden message. If the length of messages L is not known, the attack can success for 5.3%r 94.7%; if L is known, the attack can success for 1.1%r 98.4%, and by using the estimator for n, the attacking speed can be increased by 10%~45% when 11%r 50%.