public bool Extract(int mode, FileStream KeyStream, Stream MessageStream)
{
SteganoWave.WaveStream AudioStream = new SteganoWave.WaveStream(stream); /* 冗余 */
bytesPerSample = AudioStream.Format.wBitsPerSample / 8;
AudioStream.Seek(0, SeekOrigin.Begin);
/* Extra output informations */
//FileStream _fs = new FileStream(AudioHide.storage + "Message\\record01.txt", FileMode.Create);
//StreamWriter _sw = new StreamWriter(_fs);
switch (mode)
{
/* src/out/key/mes OK
* src --- this.stream
* key --- KeyStream
* message --- MessageStream
* out --- OutWave
*/
#region Improved LSB algorithm
case 0:
byte[] waveBuffer = new byte[bytesPerSample];
int cnt = 0;
int keyByte; //distance of the next carrier sample
int mes, Mes = 0;
int[] length = { 0, 0, 0, 0 };
long Length = 1000000;
while (AudioStream.ReadByte() >= 0 && MessageStream.Length < Length)
{
Mes = 0;
//if (AudioStream.Position == 1)
// AudioStream.Seek(0, SeekOrigin.Begin);
AudioStream.Seek(-1, SeekOrigin.Current);
for (int bitIndex = 0; bitIndex < 8; bitIndex++)
{
cnt++;
/* 这里看编码规则解码 值应减1 */
keyByte = GetKeyValue(KeyStream);
/* jump out of stream */
for (int i = 0; i < keyByte; i++)
{
AudioStream.Read(waveBuffer, 0, waveBuffer.Length);
}
mes = (int)(waveBuffer[waveBuffer.Length - 1] % 2 == 0 ? 0 : 1);
/* 4 Bytes for message's length */
if (cnt < 32)
{
length[(cnt - 1) / 8] += (1 & mes) << ((cnt - 1) % 8);
}
else if (cnt == 32)
{
Length = (length[3] << 24) + (length[2] << 16) +
(length[1] << 8) + length[0];
}
else
{
Mes += (1 & mes) << bitIndex;
}
}
if (cnt > 32)
{
MessageStream.WriteByte((byte)Mes);
}
}
break;
#endregion
#region parity
case 1:
/* Echo hiding methods*/
break;
#endregion
#region MCLF
case 2:
/* MCLF methods*/
break;
#endregion
default:
break;
}
/*_sw.Flush();
* _sw.Close();
* _fs.Flush();
* _fs.Close();*/
AudioStream.Dispose();
return(true);
}
public bool Hide(int mode, FileStream KeyStream, Stream MessageStream, string name)
{
FileStream OutWave = new FileStream(name, FileMode.Create);
SteganoWave.WaveStream AudioStream = new SteganoWave.WaveStream(stream, OutWave); /* 冗余 */
bytesPerSample = AudioStream.Format.wBitsPerSample / 8;
/* Extra output informations */
//FileStream _fs = new FileStream(AudioHide.storage + "Message\\record01.txt", FileMode.Create);
//StreamWriter _sw = new StreamWriter(_fs);
switch (mode)
{
/* src/out/key/mes OK
* src --- this.stream
* key --- KeyStream
* message --- MessageStream
* out --- OutWave
*/
#region Improved LSB algorithm
case 0:
byte[] waveBuffer = new byte[bytesPerSample];
byte message, bit, waveByte;
int messageBuffer; //receives the next byte of the message or -1
int keyByte; //distance of the next carrier sample
while ((messageBuffer = MessageStream.ReadByte()) >= 0)
{
message = (byte)messageBuffer;
for (int bitIndex = 0; bitIndex < 8; bitIndex++)
{
keyByte = GetKeyValue(KeyStream);
/* copy the previous sample point */
for (int i = 0; i < keyByte - 1; i++)
{
Copy(waveBuffer, 0, waveBuffer.Length, OutWave);
}
/* modify the last bit of the selected point */
stream.Read(waveBuffer, 0, waveBuffer.Length);
waveByte = (byte)(waveBuffer[bytesPerSample - 1] % 2);
bit = (byte)(((message & (byte)(1 << bitIndex)) > 0) ? 1 : 0);
if ((bit ^ waveByte) == 1)
{
waveByte = (byte)(waveByte > 0 ? -1 : 1);
waveBuffer[bytesPerSample - 1] += waveByte;
}
OutWave.Write(waveBuffer, 0, bytesPerSample);
}
}
//copy the rest of the wave without changes
waveBuffer = new byte[stream.Length - stream.Position];
stream.Read(waveBuffer, 0, waveBuffer.Length);
OutWave.Write(waveBuffer, 0, waveBuffer.Length);
break;
#endregion
#region parity
case 1:
/* Echo hiding methods*/
break;
#endregion
#region MCLF
case 2:
/* MCLF methods*/
break;
#endregion
default:
break;
}
/*_sw.Flush();
* _sw.Close();
* _fs.Flush();
* _fs.Close();*/
OutWave.Close();
return(true);
}
