internal static string GetHiddenValue(StegoBitmap bitmap, Channel channel)
{
byte[] hidden = bitmap.GetChannel(channel);
bool[] headerBits = hidden.Take(16).SelectMany(x => GetNLastBit(x, 1)).ToArray();
byte E = BoolArrayToByte(headerBits.Take(8).ToArray());
byte lengthSize = BoolArrayToByte(headerBits.Skip(8).Take(8).ToArray());
bool[] lengthBits = hidden.Skip(16).Take(lengthSize * 8).SelectMany(x => GetNLastBit(x, 1)).ToArray();
List <byte> lengthBytes = new List <byte>();
for (int i = 0; i < lengthBits.Length; i += 8)
{
lengthBytes.Add(BoolArrayToByte(lengthBits.Skip(i).Take(8).ToArray()));
}
int length = GetIntFromBytes(lengthBytes);
bool[] bits = hidden.Skip(16 + lengthSize * 8).Take(length * 8).SelectMany(x => GetNLastBit(x, 1)).ToArray();
List <byte> bytes = new List <byte>();
for (int i = 0; i < bits.Length; i += 8)
{
bytes.Add(BoolArrayToByte(bits.Skip(i).Take(8).ToArray()));
}
return(ByteArrayToString(bytes.ToArray()));
}
internal static Bitmap Hide(StegoBitmap bitmap, string text, Channel channel)
{
byte[] sourceChannel = bitmap.GetChannel(channel);
byte flag = Convert.ToByte('E');
byte size = GetSizeOfLength(text.Length);
byte[] length = GetLengthInBytes(text.Length, size);
byte[] stegoText = StringToByteArray(text);
byte[] stegoBytes = new byte[1 + 1 + length.Length + stegoText.Length];
stegoBytes[0] = flag;
stegoBytes[1] = size;
int counter = 0;
for (int i = 0; i < length.Length; i++)
{
stegoBytes[i + 2] = length[counter++];
}
counter = 0;
for (int i = 0; i < stegoText.Length; i++)
{
stegoBytes[i + 2 + length.Length] = stegoText[counter++];
}
bool[] stegoBits = stegoBytes.SelectMany(x => ByteToBoolArray(x)).ToArray();
for (int i = 0; i < stegoBits.Length; i++)
{
if ((sourceChannel[i] % 2 == 0) && stegoBits[i])
{
sourceChannel[i]++;
}
else if ((sourceChannel[i] % 2 == 1) && !stegoBits[i])
{
sourceChannel[i]--;
}
}
return(new StegoBitmap(bitmap, sourceChannel, channel).GetImage());
}
