Spread-spectrum watermarking of audio signals

Watermarking has become a technology of choice for a broad range of multimedia copyright protection applications. Watermarks have also been used to embed formatindependent metadata in audio/video signals, in a way that is robust to common editing. In this paper, we present several novel mechanisms for effective encoding and detection of directsequence spread-spectrum watermarks in audio signals. The developed techniques aim at: (i) improving detection convergence and robustness (ii) improving watermark imperceptiveness, (iii) preventing de-synchronization attacks, (iv) alleviating estimation/removal attacks, and finally, (v) establishing covert communication over a public audio channel. We explore the security implications of the developed mechanisms and review watermark robustness on a benchmark suite that includes a combination of audio processing primitives including: timeand frequencyscaling with wow-and-flutter, additive and multiplicative noise, resampling, requantization, noise reduction, and filtering. Index Terms — watermarking, spread-spectrum, audio signals, covert communication, de-synchronization, estimation attacks.