Digital Audio Security Technology Research

Recently, with the rapid digital techniques, multimedia products such as images, video, audio, have been popularized, and improved greatly the efficiency and correction of communication. However, it's ease to copy, edit and transmit the content without the permission of the copyright ownership. How to protect copyright and make information safe in the network has become a problem needs to be solved immediately. Digital watermarking technique is the most effective method. As a useful tool for the copyright protection and judgment, digital watermarking technique has gained much more concerns in many ways since 1993. Audio digital watermarking technique has even been one of the research hotspots recently. With this we can embed secret information into digital audio signal, to protect copyright.In this paper we focus on a new class of orthogonal function systems, U systems and V systems. Both are composed by a series of piecewise polynomials of degree k, and they are all complete orthogonal function systems with features of smooth orthogonal functions and discontinuous orthogonal functions. These unique characters can be used in information hiding and digital watermarking. Contribution in this thesis is shown as follows from two aspects:1. Propose a novel robust audio digital watermarking algorithm based on U system. The watermark signal is embedded into the low and middle frequency part of the U transformed audio files in order to guarantee the quality of the audio and to increase the amount of watermarks. The experiments show that the suggested algorithm is robust to classical attacks, such as White Gaussian Noise, resampling, filtering, cutting and so on, and it can be used to identify the audio copyright.2. Propose a novel dual audio digital watermarking algorithm based on V system. The robust watermark is embedded into the low and middle frequency to identify the audio copyright. The fragile watermark is embedded by quantizing high frequency coefficients of audio signal in order to verify its originality. Which shows that the robust watermark is robust to many classical attacks while the fragile watermark is inaudible and sensitive to operations such as filtering, performed on audio signal in dual watermarks system.