The Research For Digital Audio Watermark Algorithm

The wide application of the multimedia technology has resulted in a strong demand for encryption, authentication and copyright protection for multimedia data. As the authentication ways of tradition encryption is helpless to the protection of multimedia content, the watermark technique is put forward under this condition. Digital watermarking is the technology of embedding secret information into digital multimedia data such as digital audio, image or video using signal processing technology. Making use of the information hiding in the multimedia data can verify the author, purchaser or confirm the multimedia content. In this paper, we advance an applied scheme of digital audio watermarking and implement three audio watermark algorithms on the base of analyzing the characters and method of the audio watermark technology. And we analyze their specialty, merit and deficiency. At last, we conclude the work during my master period, and make a prospect for the future.First, we give a general concept of the audio watermarking. We introduce the audio watermark character and application. And we summarize the character of the human auditory system, especially the psychoacoustic modal. The analysis of this can give the inaudible, redundant elements of audio. In this paper we employ it to guarantee the inaudibility of the embedded watermark.Because of the good properties of intangibility, impartibility and common change, the audio watermark has a comprehensive application. We advance an applied scheme of digital audio watermarking for copyright protection and the copy controlling with the cryptology on the base of summarizing the audio watermark application.First, compute the audio works' copyright mark E, sequence number S, then we compute the encrypted , and encrypt the copy controlling mark C to whose key is , get watermark key by using and S. And at the last, we write , S and into the INAM, IKEY, ICOP information which are located in the head of Wav file. When extracting the watermark, we first get the , S and . If they are existed or not to be decrypted, then we judge this file as pirate and prohibit its play; else we use to decrypted and get the copy state of this file. Then we compute the watermark key using and S and extract it.A new spatial digital audio watermark algorithm is presented by analyzing the merit and deficiency of all spatial domain watermark algorithm. In the algorithm, we take the linear offset register sequence as the watermark information, and enhance the robustness of watermark by using spread spectrum, mix and synchronization. This algorithm has features as followed:Using public key and private key makes the attacker fail without any of them, enhancing the secrecy; Using double watermarks enhances the robustness of the private watermark by the protection of the public watermark;Using synchronization enhances the robustness of the watermark to resist the attack of compression and resampling. Only changing the least significant bit enhances the transparence.The experiment results tell us that the algorithm has a good transparence and robustness to resist the attacks. In the fragile watermark algorithm, we use MD5 algorithm and implement the authentication of the content. While inserting, we use the last bit of each byte to compose the sampling sequence whose length is the number of primary samples subtracts 256. Then we use MD5 to compute the sampling sequence and get the index value, which is 256 bits. At the last we use the index as fragile watermark to insert the last bit of the residuary 256 primary samples.While extracting, we use the same method as inserting; first we get the sampling sequence whose length is (S-256). Then use MD5 to compute the index and to extract the from the last bit of the residuary 256 samples. If , the audio hasn't been attacked or tampered.In the audio watermark algorithms of the frequency domain, we discuss the watermark algorithm based on the low frequency of DWT. Because the chaotic sequences have good properties of...