Highly transparent and secure scheme for concealing text within audio

Abstract

This paper presents a highly transparent and secure scheme for concealing text within audio, based on Quantization Index Modulation and Orthogonal Variable Spreading Factor. The audio signal is decomposed through the Discrete Wavelet Transform and the approximation coefficients are selected to embed the text. Every character of the text is represented by a 256-bit orthogonal code, through mapping operations between the ASCII integer representation of the character and an external key. For improving the quality of recovered data, a repetition code is applied in the embedding process. Several tests were performed in order to measure the transparency of the output audio signal (i.e. stego signal) and the security of the recovered one. The main advantage of our proposal is the good trade-off among transparency, security and hiding capacity.