Steganalysis for Markov Feature of Difference Array in DCT Domain

Abstract

In this paper, an effective steganalysis method based on Markov transition matrix is proposed to attacking the advanced JPEG steganographic schemes. As the horizontal and vertical scan modes failed to detect F5 steganography with low imbedding-rate, zigzag scanning pattern is developed to arrange both DCT (Discrete Cosine Transform) blocks and coefficients in each block. Difference computation was applied on the arranged JPEG 2-D array, which enhanced the variation caused by data embedding. Threshold and truncation techniques are utilized to make the computational complexity of the proposed method manageable. Bidirectional Markov matrix is exploited to capture the correlations between the adjacent coefficients in both intra-block and inter-block senses, which have been changed during data embedding. Features for steganalysis are derived from intra-block and inter-block Markov transition matrixes. The experiment works have demonstrated the effectiveness of the proposed scheme, which greatly improves the capability of steganalysis, the detection accuracy for each steganography at embedding-rate 0.05 exceeds 95%.

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“…However with the current techniques for cryptanalysis, we can prove with acceptable accuracy that the cover medium has been exposed to manipulation. By cover medium we mean the data carrier for the hidden messageZhou and Hui [16], Abolghasemi et al [1], Zhi-ping et al [15] .…”

“…The steganographic procedure acts as a encapsulation to the hidden data and this encapsulated data is secured by a cryptographic key. Second, we added encryption to steganography by manipulating the hidden data, not the cover medium in the data preparation step this act as a counter measure to steganographic detection [16,1,15] B. Secure steganography…”

“…This is a simple question of why do we need to encrypt an existing security protocol and the reason is simple. Because of the advanced method mentioned in [16,1,15] it is relatively easy to detect data manipulation. Since it's relatively easy to detect then it's relatively easy to extract the hidden information [14].…”

“…Since we will use it for data storage we expect that it will be exposed to malicious attacks to extract the personal data thus we need a way to secure it. Second, since there are many advanced methods mentioned in [16,1,15] to detect changes in digital media and indicate the usage of stenographic techniques that malicious attackers, we think it's a good idea to incorporate the encryption into our scheme of steganography to prevent cryptanalysis. Because even if the malicious attackers found out that the media contains hidden data (audio medium stream) and they where able to extract the data they can not obtain its contents without the key which contains the encryption sequence.…”