void ProcessPNG(bool find = true)
{
foreach (PNGChunk chunk in image.Chunks)
{
if (chunk.Name == "IDAT")
{
key = (byte[])chunk.Data.Clone();
break;
}
}
if (key == null)
{
throw new PNGMaskException("PNG has no IDAT chunk for the SteganographyProvider to process.");
}
if (find)
{
PNGChunk eof = image.Chunks[image.Chunks.Count - 1];
if (eof.Name == "_EOF")
{
vector = (byte[])eof.Data.Clone();
string pass = SteganographyProvider.AskPassword();
if (pass != null && pass.Length > 0)
{
PrepareKey(Encoding.UTF8.GetBytes(pass));
}
}
}
}
void ProcessPNG(bool find = true)
{
foreach (PNGChunk chunk in image.Chunks)
{
if (chunk.Name == "IDAT")
{
key = (byte[])chunk.Data.Clone();
break;
}
}
if (key == null)
{
throw new PNGMaskException("PNG has no IDAT chunk for the SteganographyProvider to process.");
}
if (find)
{
PNGChunk pdata = default(PNGChunk);
bool skip = true, pdatafound = false;
foreach (PNGChunk chunk in image.Chunks)
{
if (chunk.Name == "IDAT")
{
if (skip)
{
skip = false;
continue;
}
pdata = chunk;
pdatafound = true;
}
}
if (pdatafound)
{
vector = (byte[])pdata.Data.Clone();
string pass = SteganographyProvider.AskPassword();
if (pass != null && pass.Length > 0)
{
PrepareKey(Encoding.UTF8.GetBytes(pass));
}
}
}
}
public override byte[] ExtractData()
{
string pass = SteganographyProvider.AskPassword();
if (pass != null && pass.Length > 0)
{
csprng = SteganographyProvider.PrepareISAAC(Encoding.UTF8.GetBytes(pass));
}
byte[] len = new byte[4];
int temp = 0;
int j = 0;
for (int i = 0; i < 4; i++)
{
len[i] |= (byte)(BitmapData[j] & 3);
IterateChannel(ref temp, ref j);
len[i] |= (byte)((BitmapData[j] & 3) << 2);
IterateChannel(ref temp, ref j);
len[i] |= (byte)((BitmapData[j] & 3) << 4);
IterateChannel(ref temp, ref j);
len[i] |= (byte)((BitmapData[j] & 3) << 6);
IterateChannel(ref temp, ref j);
}
int isaac = 0;
if (csprng != null)
{
for (int k = 0; k < len.Length; k++, isaac++)
{
len[k] = (byte)(len[k] ^ csprng.rsl[isaac]);
}
}
int ilen = BitConverter.ToInt32(len, 0);
ulong maxsize = (ulong)Math.Floor(((double)BitmapDimensions.Width * (double)BitmapDimensions.Height * 3d * 2d) / 8d);
if (ilen < 1 || (ulong)ilen > maxsize)
{
throw new InvalidPasswordException();
}
byte[] data = new byte[ilen];
for (int i = 0; i < ilen && j < BitmapData.Length; i++)
{
data[i] |= (byte)(BitmapData[j] & 3);
IterateChannel(ref temp, ref j);
data[i] |= (byte)((BitmapData[j] & 3) << 2);
IterateChannel(ref temp, ref j);
data[i] |= (byte)((BitmapData[j] & 3) << 4);
IterateChannel(ref temp, ref j);
data[i] |= (byte)((BitmapData[j] & 3) << 6);
IterateChannel(ref temp, ref j);
}
if (csprng != null)
{
for (int i = 0; i < data.Length; i++, isaac++)
{
if (isaac >= ISAAC.SIZE)
{
isaac = 0;
csprng.Isaac();
}
data[i] = (byte)(data[i] ^ csprng.rsl[isaac]);
}
}
return(data);
}
public override void ImprintData(byte[] data)
{
string pass = SteganographyProvider.AskPassword();
if (pass != null && pass.Length > 0)
{
csprng = SteganographyProvider.PrepareISAAC(Encoding.UTF8.GetBytes(pass));
}
ulong maxsize = (ulong)Math.Floor(((double)BitmapDimensions.Width * (double)BitmapDimensions.Height * 3d * 2d) / 8d);
if ((ulong)data.LongLength + 4 > maxsize)
{
throw new NotEnoughSpaceException("Not enough space for graphical injection, maximum data size for this image is " + (int)Math.Floor(maxsize / 1024d) + "KB");
}
List <byte> tdata = new List <byte>(data);
byte[] len = BitConverter.GetBytes(data.Length);
tdata.InsertRange(0, len);
data = tdata.ToArray();
tdata = null;
if (csprng != null)
{
for (int i = 0, isaac = 0; i < data.Length; i++, isaac++)
{
if (isaac >= ISAAC.SIZE)
{
isaac = 0;
csprng.Isaac();
}
data[i] = (byte)(data[i] ^ csprng.rsl[isaac]);
}
}
int temp = 0;
for (int i = 0, j = 0; i < data.Length && j < BitmapData.Length; i++)
{
byte mask1 = (byte)(data[i] & 3);
byte mask2 = (byte)((data[i] & 12) >> 2);
byte mask3 = (byte)((data[i] & 48) >> 4);
byte mask4 = (byte)((data[i] & 192) >> 6);
BitmapData[j] &= 252;
BitmapData[j] |= mask1;
IterateChannel(ref temp, ref j);
BitmapData[j] &= 252;
BitmapData[j] |= mask2;
IterateChannel(ref temp, ref j);
BitmapData[j] &= 252;
BitmapData[j] |= mask3;
IterateChannel(ref temp, ref j);
BitmapData[j] &= 252;
BitmapData[j] |= mask4;
IterateChannel(ref temp, ref j);
}
}
