Robustness of TEC speech watermarking to cropping and additive noise

The widespread use of the internet has created a need for technologies for the protection of copyrighted digital information. Digital watermarking is one such technology in which a preferably imperceptible signal ( watermark) is embedded into a copyrighted host signal. Digital watermarks are prone to a wide range of “attacks” and other forms of distortion. In this work, the robustness of a new watermarking method based on transform encryption coding (TEC) to cropping and additive noise is investigated.; Experiments were conducted to test the robustness of TEC speech watermarking to additive noise under different conditions including different SNRs and watermark masking algorithm parameters. Although a cropping attack is easy to implement, the resulting desynchronization severely hinders watermark detection and recovery. A dynamic programming (DP) based algorithm for the detection of cropped speech samples and reconstruction of the cropped stego-signal to enable watermark recovery has been developed. Implementation details of the DP algorithm and performance under different environmental conditions are presented. Factors influencing the robustness of TEC speech watermarking are analyzed.