DESIGN & EVOLUTION OF A STEGANOGRAPHY SYSTEM FOR SPEECH SIGNAL BY SLANTLET TRANSFORM

Abstract

In this paper a Stegan graphic system was proposed to hide up a secretspeech signal in a cover speech signal, using Slant let transform. The combination of a Stegangraphy and cryptography is used to increase the level of security and to make the systemmore rigid and complex to be defeated by attackers. In cryptography the secret speech signalis converted from 1-D to 2-D signal, divided into blocks each of size (8*8) sampled and thenthe samples are converted to the binary form, after that, columns transposition is applied toget the ciphered signal. This cipher signal will be the next stage, we are driving the key whichis used in cyphering process from the slantlet coefficients.The proposed system increases the imperceptibility property because it is based onreplacing each secret bit with one of the host coefficient bit (the host coefficient may be thesame as secret bit). So that changing of host signal due to embedding process was decrease dbut the dimension of the cover signal will be a tradeoff between the imperceptibilityand the capacity of the system. Imperceptibility and security test s are implemented to checkthe system. Peak signal to Noise Ratio(PSNR) & Correlation(Corr.) between cover signal &the stego - signal are carried out to evaluate the perform ance of the proposed algorithm.