public static Bitmap embedFileIntoImage(Bitmap bitmapImage, List<byte[]> filedata, int capacity = -1, string password = "", ToolStripStatusLabel toolStripStatusLabel = null, bool stealthy = true, Stealthiness stealthValue = Stealthiness.Maximum)
{
try
{
int imagewidth = bitmapImage.Width - 1;
int imageheight = bitmapImage.Height - 1;
byte[] filebytes = filedata[1];
string filehash = "";
writeOut(toolStripStatusLabel, "Encoding file into image - Please wait...");
// Calculate pre-encoded SHA1 Hash of File Data
using (SHA1CryptoServiceProvider sha1 = new SHA1CryptoServiceProvider())
filehash = Convert.ToBase64String(sha1.ComputeHash(filebytes));
// Encrypt File Data (bytes)
if (!String.IsNullOrEmpty(password))
filebytes = encryptData(filebytes, password);
// Encrypt Filename (bytes)
byte[] filenamebytes = filedata[0];
if (!String.IsNullOrEmpty(password))
filenamebytes = encryptData(filenamebytes, password);
// Convert Filename to binary
string filename = string.Empty;
foreach (byte b in filenamebytes)
filename += Convert.ToString(b, 2).PadLeft(8, '0');
// Convert length of filename (in bytes) into binary
string filenamelength = Convert.ToString(filename.Length / 8, 2).PadLeft(8, '0');
// Convert length of File Data (in bytes) into binary
string filelength = Convert.ToString(filebytes.Length, 2).PadLeft(24, '0');
// Build binary string
StringBuilder sfinal = new StringBuilder();
sfinal.Append(filenamelength);
sfinal.Append(filelength);
sfinal.Append(filename);
foreach (byte b in filebytes)
sfinal.Append(Convert.ToString(b, 2).PadLeft(8, '0'));
sfinal.Append("000");//buffer
// Check binary data will fit
int msgLen = (sfinal.Length + 16) / 8;
int pixCnt = capacity;
if(capacity < 0)
pixCnt = (int)Math.Floor((double)((GetImageCapacity(bitmapImage, stealthy, stealthValue) * 3) / 8));
// Calculate bit distribution throughout image (jump value)
//if(pixCnt)
int jmp = 0;
if (pixCnt > msgLen)
jmp = (int)Math.Floor((double)(pixCnt / msgLen));
if (jmp > 500) jmp = 500;
if (jmp == 0) jmp = 1;
string jump = Convert.ToString(jmp, 2).PadLeft(9, '0');
// Insert 'jump' value into first three pixels
for (int x = 0; x < 9; x+=3)
{
Color pixel = bitmapImage.GetPixel(x, 0);
string r = Convert.ToString(pixel.R, 2).PadLeft(8, '0').Substring(0, 7) + jump[x];
string g = Convert.ToString(pixel.G, 2).PadLeft(8, '0').Substring(0, 7) + jump[x+1];
string b = Convert.ToString(pixel.B, 2).PadLeft(8, '0').Substring(0, 7) + jump[x+2];
bitmapImage.SetPixel(x, 0, Color.FromArgb(Convert.ToInt32(r, 2), Convert.ToInt32(g, 2), Convert.ToInt32(b, 2)));
}
int streamPos = 0;
int pixelPos = 0;
// Insert all binary data into image
if (pixCnt > msgLen)
{
for (int y = 1; y < imageheight - 1; y++)
{
for (int x = 1; x < imagewidth - 1; x ++)
{
if (streamPos < sfinal.Length - 3)
{
if (IsValidPixel(bitmapImage, x, y, stealthy, stealthValue))
{
if (pixelPos % jmp == 0)
{
Color pixel = bitmapImage.GetPixel(x, y);
string r = Convert.ToString(pixel.R, 2).PadLeft(8, '0').Substring(0, 7) + sfinal[streamPos];
string g = Convert.ToString(pixel.G, 2).PadLeft(8, '0').Substring(0, 7) + sfinal[streamPos + 1];
string b = Convert.ToString(pixel.B, 2).PadLeft(8, '0').Substring(0, 7) + sfinal[streamPos + 2];
bitmapImage.SetPixel(x, y, Color.FromArgb(Convert.ToInt32(r, 2), Convert.ToInt32(g, 2), Convert.ToInt32(b, 2)));
streamPos += 3;
}
pixelPos++;
}
}
}
Application.DoEvents();
}
writeOut(toolStripStatusLabel, "Encoding Complete.");
}
else {
writeOut(toolStripStatusLabel, "Image is too small to hold the specified file!");
throw new SteganoException("Image is too small to hold the specified file!");
}
writeOut(toolStripStatusLabel, "Checking integrity of embedded file - Please wait...");
// Extract data from image (and decrypt if necessary)
List<byte[]> checkdata = extractFileFromImage(bitmapImage, password, toolStripStatusLabel, stealthy, stealthValue);
string checkhash = "";
// Calculate SHA1 hash of extracted data
if (checkdata != null && checkdata.Count == 2)
using (SHA1CryptoServiceProvider sha1 = new SHA1CryptoServiceProvider())
checkhash = Convert.ToBase64String(sha1.ComputeHash(checkdata[1]));
// Check extracted SHA1 hash with pre-encoded SHA1 hash
if (checkhash == filehash && checkhash != "" && filehash != "")
{
writeOut(toolStripStatusLabel, "Integrity check PASSED.");
return bitmapImage;
}
else
{
writeOut(toolStripStatusLabel, "Integrity check FAILED!");
throw new SteganoException("Failed integrity check!");
}
}
catch (SteganoException ex)
{
throw new Exception(ex.Message);
}
catch (Exception ex)
{
throw new SteganoException("Stegano: " + ex.Message);
}
}
public static int GetImageCapacity(Bitmap bitmap, bool stealthy = true, Stealthiness stealthValue = Stealthiness.Maximum)
{
int cnt = -1;
try
{
for (int y = 1; y < bitmap.Height - 1; y++)
{
for (int x = 1; x < bitmap.Width - 1; x++)
if (IsValidPixel(bitmap, x, y, stealthy, stealthValue))
cnt++;
Application.DoEvents();
}
}
catch
{
}
return cnt;
}
private static bool IsValidPixel(Bitmap bitmap, int x, int y, bool stealthy = true, Stealthiness stealthValue = Stealthiness.Maximum)
{
Application.DoEvents();
if (stealthy)
{
// looks above, below, left & right of current pixel and returns false if 5 msb's of all 5 pixels match (ie all virtually the same color)
int msb = (int)stealthValue;
Color cpixel = Color.FromArgb((int)(bitmap.GetPixel(x, y).R & msb), (int)(bitmap.GetPixel(x, y).G & msb), (int)(bitmap.GetPixel(x, y).B & msb));
Color upixel = Color.FromArgb((int)(bitmap.GetPixel(x, y - 1).R & msb), (int)(bitmap.GetPixel(x, y - 1).G & msb), (int)(bitmap.GetPixel(x, y - 1).B & msb));
Color dpixel = Color.FromArgb((int)(bitmap.GetPixel(x, y + 1).R & msb), (int)(bitmap.GetPixel(x, y + 1).G & msb), (int)(bitmap.GetPixel(x, y + 1).B & msb));
Color lpixel = Color.FromArgb((int)(bitmap.GetPixel(x - 1, y).R & msb), (int)(bitmap.GetPixel(x - 1, y).G & msb), (int)(bitmap.GetPixel(x - 1, y).B & msb));
Color rpixel = Color.FromArgb((int)(bitmap.GetPixel(x + 1, y).R & msb), (int)(bitmap.GetPixel(x + 1, y).G & msb), (int)(bitmap.GetPixel(x + 1, y).B & msb));
//return !((cpixel.GetHue() == upixel.GetHue()) && (cpixel.GetHue() == dpixel.GetHue()) && (cpixel.GetHue() == lpixel.GetHue()) && (cpixel.GetHue() == rpixel.GetHue()));
return !(cpixel.Equals(upixel) && cpixel.Equals(dpixel) && cpixel.Equals(lpixel) && cpixel.Equals(rpixel));
}
else { return true; }
}
public static List<byte[]> extractFileFromImage(Bitmap sourceImage, string password = "", ToolStripStatusLabel toolStripStatusLabel = null, bool stealthy = true, Stealthiness stealthValue = Stealthiness.Maximum)
{
try
{
// Extract jump value from first 3 pixels
StringBuilder sb = new StringBuilder();
for (int x = 0; x < 9; x += 3)
{
Color pixel = sourceImage.GetPixel(x, 0);
string r = Convert.ToString(pixel.R, 2).PadLeft(8, '0').Substring(7, 1);
string g = Convert.ToString(pixel.G, 2).PadLeft(8, '0').Substring(7, 1);
string b = Convert.ToString(pixel.B, 2).PadLeft(8, '0').Substring(7, 1);
sb.Append(r + g + b);
}
int jump = Convert.ToInt32(sb.ToString(0, 9), 2);
int imagewidth = sourceImage.Width - 1;
int imageheight = sourceImage.Height - 1;
StringBuilder sbfinal = new StringBuilder();
int pixelPos = 0;
// Extract ALL lsb's from image using jump value
for (int y = 1; y < imageheight - 1; y++)
{
for (int x = 1; x < imagewidth - 1; x++)
{
if (IsValidPixel(sourceImage, x, y, stealthy, stealthValue))
{
if (pixelPos % jump == 0)
{
Color pixel = sourceImage.GetPixel(x, y);
string r = Convert.ToString(pixel.R, 2).PadLeft(8, '0').Substring(7, 1);
string g = Convert.ToString(pixel.G, 2).PadLeft(8, '0').Substring(7, 1);
string b = Convert.ToString(pixel.B, 2).PadLeft(8, '0').Substring(7, 1);
sbfinal.Append(r + g + b);
}
pixelPos++;
}
}
}
// Get filename length (in bytes) value from first 8 bits
int filenamelength = Convert.ToInt32(sbfinal.ToString(0, 8), 2);
// Get file data length (in bytes) value from next 24 bits
int filesize = Convert.ToInt32(sbfinal.ToString(8, 24), 2);
// Get filename
byte[] filenamebytes = GetBytesFromBinaryString(sbfinal.ToString(32, filenamelength * 8));
// Decrypt filename (if necessary)
if (!String.IsNullOrEmpty(password))
filenamebytes = decryptData(filenamebytes, password);
// Check for valid filename
if (!IsASCII(filenamebytes))
throw new SteganoException("Bad Decrypt");
// Extract remaining file data
byte[] filebytes = GetBytesFromBinaryString(sbfinal.ToString(32 + (filenamelength * 8), filesize * 8));
// Decrypt file data (if necessary)
if (!String.IsNullOrEmpty(password))
filebytes = decryptData(filebytes, password);
List<byte[]> data = new List<byte[]>();
data.Add(filenamebytes);
data.Add(filebytes);
return data;
}
catch (SteganoException ex)
{
toolStripStatusLabel.Text = "Bad Decrypt. Wrong Password???";
throw new Exception(ex.Message);
}
catch
{
toolStripStatusLabel.Text = "Bad Decrypt. Wrong Password???";
throw new SteganoException("Bad Decrypt");
}
}