Speech Steganography based on Double Approximation of LSFs Parameters in AMR Coding

A steganographic method for VoIP applications based on line spectral frequency (LSF) modification, is proposed in this paper. The aim of this research is to securely transmit secret binary data into AMR cover bitstream. The proposed scheme is Newton-based interpolation of the LSF coefficients of the four sub-frames, alongside with the original linear interpolation. Newton interpolation gives a perfect similarity to linear interpolation when there is no secret information is being transmitted. Besides that, Newton interpolation provides a high flexibility, which doesn’t exist in linear interpolation, to modify the eight LSF coefficients from within ten, excluding the first and the tenth LSFs. The results show that after a slight modification of ±0.01 (D) during LSF interpolation using our proposed scheme, the intelligibility is perceived, the maximum steganographic quality change is 0.08 MOS. The proposed scheme provides a high capacity of 1.05 kbps, a high undetectability, and security level against statistical steganalysis. Hence, our proposed steganographic method is effective, secure and, avoid rising the suspicious to eavesdropper who is listening to the channel.