Content Dependent Data Hiding on GSM Full Rate Encoded Speech

This paper introduces a steganographic approach to embed data on compressed speech bit stream in order to hide secret data. This method may be used by any kind of encoded bit stream, but this research concentrates on full rate (GSM 6.10) encoded bit stream. This method allows user to adjust embedded data bit-rate or speech quality. Speech quality is determined by Perceptual Evaluation of Speech Quality (PESQ) which is an objective testing. The effect of embedding data to each specific bit of GSM Full Rate coefficients, on speech quality has been investigated and the less important bits are selected to embed secret data. Meanwhile for approaching a higher speech quality, the data embedding positions are based on different speech frame types. In other words the proposed technique is modified to achieve a content dependent algorithm.