The Technology Research On Steganalysis Of Compressed Domain Audio

Steganography is an important branch of information hiding, and a primary techniqueinstrument that is used to actualize covert communication. Steganalysis, also known assteganography detection, is attack to steganography. Its main purpose is to examine the existenceof secret information up to destroy covert communication. Compressed domain audio MP3iseasily to be used as steganographic carrier, and a variety of steganographic tools based on MP3carrier has been appeared, such as MP3Stego and UnderMP3Cover. In order to maintain thesecurity of network communications, proposing steganalysis algorithm for MP3audio is of greatsignificance. This dissertation mainly includes the following three aspects:Firstly, the MP3audio encoding theory is deeply analyzed and the quantization, entropycoding and bit packaging aspects which are closely related to steganography and steganalysis aremainly focused on; the basic idea of steganography method of compressed domain audio issummarized and the research status on steganalysis method of compressed domain audio isreviewed.Secondly, as for MP3Stego, the steganography method is analyzed deeply and two kinds ofsteganalysis method for MP3Stego are proposed through analyzing the changes caused by theoperation of steganography to original audio carrier. Through analyzing the statistical changes ofmain_data_begin after the operation of steganography, the first method is to extract the relevantstatistics of main_data_begin as feature for detecting MP3Stego; the second method is to extractthe detection feature by the sparsity changes of MDCT coefficients after the operation ofsteganography. The experimental results show that the performance of detection is still good whenthe embedding strength is low. Meanwhile, using the steganlytic features calibrated byrecompression can improve the detection performance. Thirdly, as for UnderMP3Cover, based on the in-depth analysis of its steganographyprinciple, a method for detecting UnderMP3Cover is proposed inspired by the RS detectionmethod. Moreover, the algorithm of estimating the embedding ratio is given and the deficienciesfor applying RS detection method to UnderMP3Cover are also analyzed. The experimentalresults show that the proposed algorithm can effectively attack the UnderMP3Cover. Meanwhile,the relationship between the parameters of RS method and the performance of the proposedalgorithm is given.