Audible Secret Keying for Time-Spread-Echo Based Audio Watermarking

This paper deals with the pseudo noise (PN) generating method for digital audio watermarking using time-spread echo hiding. In time-spread echo based audio watermarking, the secret payload is embedded in the form of multiple echoes spread by a pseudo noise sequence and the pseudo noise sequence is used as secret key. Generally, the pseudo noise sequence is required to be uncorrelated with other sequence and therefore typically generated by an M-sequence generator. In this paper, we propose a key sequence generating method which generates a key sequence from an audio signal. By using the new key sequence generated from an audio signal instead of an M-sequence, the key information users have to remember is their secret audio signal but not a complicated random PN key. Therefore, the availability of digital audio watermarking would be improved. After introducing the new key generation method, we evaluated the proposed key sequence. The result shows it can detect a secret payload similar to use of a conventional M-sequence and does not deteriorate inaudibility of the embedded watermark.