/// <summary>
/// This function enabels you to hide a message insider a BMP
/// </summary>
/// <param name="inputPath">input BMP path</param>
/// <param name="outputPath">output BMP path</param>
/// <param name="message">message to hide</param>
public void HideMessage(string inputPath,string outputPath,string message)
{
int readByte;
int count=14;
BMP bitmap=new BMP(inputPath);
bitmap.BitmapFileHeader.bfOffBits+=(message.Length+1);
bitmap.BitmapFileHeader.bfSize+=(message.Length+1);
FileStream br=new FileStream(inputPath,FileMode.Open);
BinaryWriter bw=new BinaryWriter(File.OpenWrite(outputPath));
bitmap.WriteBMPFileHeader(bw);
br.Seek(14,SeekOrigin.Begin);
while(count<(bitmap.BitmapFileHeader.bfOffBits-(message.Length+1)))
{
bw.Write((byte)br.ReadByte());
count++;
}
for(int i=0;i<message.Length;i++)
{
bw.Write(message[i]);
}
bw.Write(Convert.ToByte(message.Length));
while((readByte=br.ReadByte())>=0)
{
bw.Write((byte)readByte);
}
bw.Close();
br.Close();
}
/// <summary>
/// Retrives a hidden message from a BMP
/// </summary>
/// <param name="path">path of BMP</param>
/// <returns>the hidden message</returns>
public string RetrieveMessage(string path)
{
int length;
StringBuilder message=new StringBuilder();
BinaryReader br=new BinaryReader(File.OpenRead(path));
BMP bitmap=new BMP(path);
br.BaseStream.Seek(bitmap.BitmapFileHeader.bfOffBits-1,SeekOrigin.Begin);
length=(int)br.ReadByte();
br.BaseStream.Seek(-(length+1),SeekOrigin.Current);
message.Append(br.ReadChars(length));
br.Close();
return message.ToString();
}
