Robust and secure watermarking scheme for breath sound

Due to the development of the Internet, security and intellectual property protection have attracted significant interest in the copyright protection field recently. A novel watermarking scheme for breath sounds, combining lifting wavelet transform (LWT), discrete cosine transform (DCT), singular value decomposition (SVD) and dither modulation (DM) quantization is proposed in this paper as a way to insert encrypted source and identity information in breath sounds while maintaining significant biological signals. In the proposed scheme, LWT is first performed to decompose the signal, and then DCT is applied on the approximate coefficients. SVD is carried out on the LWT–DCT coefficients to derive singular values. DM is adopted to quantize the singular values of each of the LWT–DCT blocks; thus, the watermark extraction is blind by using the DM algorithm. The novelty of our proposed method also includes the introduction of the particle swarm optimization (PSO) technique to optimize the quantization steps for the DM approach. The experimental results demonstrate that the proposed watermarking scheme obtains good robustness against common manipulation attacks and preserves imperceptivity. The performance comparison results verify that our scheme outperforms existing approaches in terms of robustness and imperceptibility.

► A new watermarking scheme for breath sound based on LWT–DCT–SVD and DM is proposed.
► Identification information is inserted in the singular values of LWT–DCT coefficients.
► PSO is adopted to optimize the quantization step.
► Simulation results validate good robustness and imperceptibility of our method.