AUDIO STEGANOGRAPHY BASED ON SIGNAL MODULATION IN WAVELET DOMAIN

In this paper, an audio steganography system is proposed to hide a sequence of binary digits (bits) in digital audio data. The hiding method is based on applying amplitude modulation technique on wavelet transform coefficients. The embedding schema implies partitioning the audio signal (cover) into a number of non overlap slices, then the average of AC energy of all slices are examined; and the slices have the highest energy are considered as good hosts for secret bit. The shift in coefficients values, caused by embedding process, may cause modification in the energy status of the host slice; this problem is avoided by applying an algebraic manipulation so as to ensure that the extraction detector can to correctly identify the audio host slices. Bits insertion is done by transforming the selected host slices into wavelet domain using the biorthogonal tap (97) wavelet filters. Then, some of the highly valued coefficients of the high frequency subband are quantized to use them to host the secret bits {0, 1} by adding or subtracting a modulation step. The test results indicated that a perfect retrieval of secret bits could attained, while the hiding rate is small and the quality of stego objects is high.