High-capacity invertible data-hiding algorithm for digital audio

Abstract

A high-capacity, data-hiding algorithm that lets the user embed a large amount of data in a digital audio signal is presented in this paper. The algorithm also lets the user restore the original digital audio from the watermarked digital audio after retrieving the hidden data. The hidden information can be used to authenticate the audio, communicate copyright information, facilitate audio database indexing and information retrieval without degrading the quality of the original audio signal, or enhance the information content of the audio. It also allows secret communication between two parties over a digital communication link. The proposed algorithm is based on a generalized, reversible, integer transform, which calculates the average and pair-wise differences between the elements of a vector composed from the audio samples. The watermark is embedded into the pair-wise difference coefficients of selected vectors by replacing their least significant bits (LSB) with watermark bits. Most of these coefficients are shifted left by one bit before replacing their LSB. The vectors are carefully selected such that they remain identifiable after embedding and they do not suffer from overflow or underflow after embedding. To ensure reversibility, the locations of the shifted coefficients and the original LSBs are appended to the payload. Simulation results of the algorithm and its performance are presented and discussed in the paper.