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));
}
}
}
}
public PNGChunk ReadChunk()
{
PNGChunk chunk = new PNGChunk();
byte[] lengthArray = new byte[4];
byte[] typeArray = new byte[4];
byte[] dataArray = new byte[] { };
byte[] crcArray = new byte[4];
//Read length and assign it to the ChunkLength
lengthArray = fileReader.ReadBytes(4);
chunk.ChunkLength = ReadLength(lengthArray);
//Read the chunk type and assign it to the ChunkType
typeArray = fileReader.ReadBytes(4);
chunk.ChunkType = ReadType(typeArray);
//Read the chunk data and assign it to the ChunkData
chunk.ChunkData = fileReader.ReadBytes((int)chunk.ChunkLength);
//Read the crc and assign it the Crc
crcArray = fileReader.ReadBytes(4);
chunk.Crc = ReadLength(crcArray); //uses same code as the length because it is a 32-bit integer.
return(chunk);
}
void dIHDR(PNGChunk c)
{
IHDRChunk ic = new IHDRChunk(c);
ind();
wo("Width: " + ic.Width);
wo("Height: " + ic.Height);
wo("BitDepth: " + ic.BitDepth);
wo("ColorType: " + ic.ColorType + " " + decodeColorType(ic));
oud();
}
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));
}
}
}
}
/// <summary>
/// Loads PNG header from stream.
/// </summary>
/// <param name="stream">Fully formatted header stream. Position not relevant, but not reset.</param>
/// <returns>Header length.</returns>
protected override long Load(Stream stream)
{
base.Load(stream);
byte[] temp = stream.ReadBytes(HeaderSize);
if (!CheckIdentifier(temp))
{
throw new FormatException("Stream is not a PNG Image");
}
PNGChunk header = new PNGChunk(temp);
Width = MyBitConverter.ToInt32(header.ChunkData, 0, MyBitConverter.Endianness.BigEndian);
Height = MyBitConverter.ToInt32(header.ChunkData, 4, MyBitConverter.Endianness.BigEndian);
BitDepth = header.ChunkData[8];
colourType = (ColourType)header.ChunkData[9];
CompressionMethod = (CompressionMethods)header.ChunkData[10];
FilterMethod = (FilterMethods)header.ChunkData[11];
InterlaceMethod = (InterlaceMethdods)header.ChunkData[12];
return(-1); // Since we don't know the length of the entire header, no point returning any value.
}
//Loads the chunks of the PNG file from the `filename` in the parameter and returns PNGFile object
public static PNGFile Load(string fileName)
{
PNGFile pngChunkCol = new PNGFile();
using (PNGFileReader pngReader = new PNGFileReader(fileName))
{
PNGChunk pChunk = pngReader.ReadChunk();;
while (true)
{
if (pChunk.ChunkType == "IEND")
{
pngChunkCol.PngChunks.Add(pChunk);
break;
}
else
{
pngChunkCol.PngChunks.Add(pChunk);
pChunk = pngReader.ReadChunk();
}
}
}
return(pngChunkCol);
}
/// <summary>
/// Loads PNG header from stream.
/// </summary>
/// <param name="stream">Fully formatted header stream. Position not relevant, but not reset.</param>
/// <returns>Header length.</returns>
protected override long Load(Stream stream)
{
base.Load(stream);
byte[] temp = stream.ReadBytes(HeaderSize);
if (!CheckIdentifier(temp))
throw new FormatException("Stream is not a PNG Image");
PNGChunk header = new PNGChunk(temp);
Width = MyBitConverter.ToInt32(header.ChunkData, 0, MyBitConverter.Endianness.BigEndian);
Height = MyBitConverter.ToInt32(header.ChunkData, 4, MyBitConverter.Endianness.BigEndian);
BitDepth = header.ChunkData[8];
colourType = (ColourType)header.ChunkData[9];
CompressionMethod = (CompressionMethods)header.ChunkData[10];
FilterMethod = (FilterMethods)header.ChunkData[11];
InterlaceMethod = (InterlaceMethdods)header.ChunkData[12];
return -1; // Since we don't know the length of the entire header, no point returning any value.
}
private void ReadChunk(BinaryReader b)
{
PNGChunk c = new PNGChunk();
byte[] blen = b.ReadBytes(4);
if (BitConverter.IsLittleEndian)
Array.Reverse(blen);
int len = BitConverter.ToInt32(blen, 0);
c.Type = Encoding.ASCII.GetString(b.ReadBytes(4));
c.Data = b.ReadBytes((int)len);
c.RawCRC = b.ReadBytes(4);
Chunks.Add(c);
}
