Designing and Evaluation of Performance of a Spread Spectrum Technique for Audio Steganography

Steganography is the art and science of hiding that a communication is taken place. It embeds the secret file (text, audio or image) in other carrier file. Audio information hiding has attracted more attentions recently. Spread spectrum (SS) technique has developed rapidly in this area due to the advantages of good robustness and immunity to noise attack. Spread spectrum techniques really of digital communications systems. Two commonly spread spectrum techniques are used direct sequence spread spectrum (DSSS) and frequency hopped spread spectrum (FHSS). Implementation of steganography in audio data using Direct Sequence Spread Spectrum method has been presented in this thesis. The message is transmitted through noise-like wave. This method can be applied to embed messages in audio data. The embedded audio data will be heard as noise. In this thesis Direct Sequence Spread Spectrum method is used. A key is needed to embed messages into noise , this key is used to generate pseudo-random key sequence. The information to be embedded must first modulated using the pseudorandom key sequence. Also, Random location selection to embed the data within the cover image pixels is also proposed in the work. These modifications give a more secure stegno-graphic system, making guesses about the bit-rate or message length less feasible. The proposed stego and extraction system uses DSSS technique. These are used to increase the security and robustness of the system. Improvement has been achieved in robustness on the expense of reducing the capacity of hiding. The imperceptibility of the stego audio and extracted image is assessed by using peak signal-to-noise ratio (PSNR) and normalized correlation measure. Keywords— Audio Steganography; Cryptography Spread Spectrum (SS) technique; Information Security, secret Key