aurecover.m

%aurecover
%Author:Ankur Pawar
%Description: Steganography in wav file using lsb method
%Date of creation :19 Nov 2009
%sample file:new2.wav
[filename, pathname] = uigetfile('*.wav','Select a file');        
[y,fs,nbits,opts]=wavread([pathname filename],[1 2]);

%open the file with hidden text
fid1=fopen([pathname filename],'r'); 
header=fread(fid1,40,'uint8=>char');
data_size=fread(fid1,1,'uint32');

%read the wave data samples
[dta,count]=fread(fid1,inf,'uint16');

%close the file,only wav data samples are sufficient for extracting the text
ans=fclose(fid1);

lsb=1;

identity=bitget(dta(1:8),lsb)';
if identity==[1 0 1 0 1 0 1 0]

    %extract the length of text from first 9th to 28th wav data samples 
    len_bin=zeros(20,1);
    m_bin=zeros(10,1);
    n_bin=zeros(10,1);

    m_bin(1:10)=bitget(dta(9:18),lsb);
    n_bin(1:10)=bitget(dta(19:28),lsb);
    
    %convert the length to decimal
    %len=bi2de((len_bin)');
    len=bi2de(m_bin')*bi2de(n_bin');


    secmsg_bin=zeros(len,1);
    
    %extract the lsb from wave data sample
    secmsg_bin(1:len)=bitget(dta(29:28+len),lsb);
    secmsg_bin_re=reshape(secmsg_bin,len/8,8);

    secmsg_double=bi2de(secmsg_bin_re); %convert it to decimal

    secmsg=char(secmsg_double)'  %convert to char(ASCII)
end