} // End method Crossover().
/// <summary>
/// Mutate (XOR) the intermediate image with a secret
/// image stored in the key.
/// </summary>
/// <param name="s3">
/// The stream array that is used to select a pseudo-random row index
/// for XOR-ing with a secret image.
/// </param>
/// <param name="s4">
/// The stream array that is used to select a pseudo-random column
/// index for XOR-ing with a secret image.
/// </param>
private void Mutate(int[] s3, int[] s4)
{
int m = PlaintextImage.Height; // Number of rows.
int n = PlaintextImage.Width; // Number of columns.
// The (x, y) pixel value from the intermediate image.
uint intermediate = 0;
// The (s3[x], s4[y]) pixel value from the secret image.
uint secret = 0;
// The "mutated" pixel is the exclusive-or (XOR) of the
// intermediate pixel and the secret key pixel.
uint xor = 0;
for (int y = 0; y < m; ++y)
{
for (int x = 0; x < n; ++x)
{
intermediate = (uint)CiphertextImage.
GetPixel(x, y).ToArgb();
secret = (uint)Key.SecretImage.
GetPixel(s3[x], s4[y]).ToArgb();
xor = ((uint)(intermediate ^ secret) | 0xff000000);
CiphertextImage.SetPixel(x, y, Color.FromArgb((int)xor));
}
}
} // End method Mutate().
/// <summary>
/// Applies the k-epsilon dissipative turbulence
/// value to the secret image.
/// </summary>
private void ApplyDissipativeTurbulence()
{
// Retrieve the size of the image in pixels.
int m = PlaintextImage.Width;
int n = PlaintextImage.Height;
// This is the scalar value to apply to the XOR operation.
byte scalar = GetTurbulenceMultiplier();
// For every pixel in the image, XOR its value with the
// value of the secret image and the turbulence scalar value.
for (int y = 0; y < n; ++y)
{
for (int x = 0; x < m; ++x)
{
int pixel = CiphertextImage.GetPixel(x, y).ToArgb();
int secPixel = Key.SecretImage.GetPixel(x, y).ToArgb();
// The luminance value of the XOR of the
// input image and the secret image.
byte Y = (byte)((pixel & 0x000000ff)
^ (secPixel & 0x000000ff));
// Apply the scalar value.
int xor = Y ^ scalar;
Color newPix = Color.FromArgb(0xff, xor, xor, xor);
CiphertextImage.SetPixel(x, y, newPix);
}
}
} // End method ApplyDissipativeTurbulence().
} // End method Encrypt().
/// <summary>
/// This method applies the row-wise (scanline) momentum (mass) fluxes.
/// </summary>
private void ApplyMomentumFlux()
{
// Retrieve the size of the image in pixels.
int n = PlaintextImage.Height;
int m = PlaintextImage.Width;
// Generate a logistic map to seed the mass flow rate vector.
double[] logisticMap = GenerateLogisticMap(Key.R_mdot,
Key.MassFlowRateInitializer, n);
// The row-wise mass flow rates are a true set of integers [0, n].
int[] rowMassFlowRate = new int[n];
for (int i = 0; i < n; ++i)
{
rowMassFlowRate[i] = i;
}
// Randomize the mass flow rates by the sort order
// of the logistic map vector.
Array.Sort(logisticMap, rowMassFlowRate);
// Right circular rotate each scanline in the image.
int row = 0;
for (int y = 0; y < n; ++y)
{
for (int x = 0; x < m; ++x)
{
int replacementIndex = (x + rowMassFlowRate[row]) % m;
Color replaceWith
= PlaintextImage.GetPixel(replacementIndex, y);
CiphertextImage.SetPixel(x, y, replaceWith);
}
row++;
}
} // End method ApplyMomentumFlux().
} // End method ApplyMomentumFlux().
/// <summary>
/// This method applies the column-wise heat fluxes.
/// </summary>
private void ApplyHeatFlux()
{
// Retrieve the size of the image in pixels.
int n = PlaintextImage.Height;
int m = PlaintextImage.Width;
// Generate a logistic map to seed the mass flow rate vector.
double[] logisticMap = GenerateLogisticMap(Key.R_qdot,
Key.HeatTransferInitializer, m);
// The elements of the heat flux vector are in
// the integer set [0, 255]. This is effectively an
// initialization vector for the bottom scanline.
int[] columnHeatFlux = new int[m];
for (int i = 0; i < m; ++i)
{
columnHeatFlux[i] = (int)(255 * logisticMap[i]);
}
// For every pixel in the image, XOR its value with the
// value of the pixel beneath it.
for (int x = 0; x < m; ++x)
{
for (int y = 0; y < n; ++y)
{
Color source = CiphertextImage.GetPixel(x, y);
int Tj = (source.ToArgb() & 0x000000ff);
int Tj1 = Tj ^ columnHeatFlux[x];
Color replaceWith = Color.FromArgb(0xff, Tj1, Tj1, Tj1);
CiphertextImage.SetPixel(x, y, replaceWith);
}
}
} // End method ApplyHeatFlux().
/// <summary>
/// Perform row and column crossover operations to permute the
/// image data into an intermediate image.
/// </summary>
/// <param name="s1">
/// The stream array that is used to perform row-wise crossover.
/// </param>
/// <param name="s2">
/// The stream array that is used to perform columnn-wise crossover.
/// </param>
private void CrossOver(int[] s1, int[] s2)
{
int m = PlaintextImage.Height; // Number of rows.
int n = PlaintextImage.Width; // Number of columns.
// Ensure that the number of cut points is even!
int numRowCutPoints = (int)Math.Floor((double)n / 2.0);
int numColCutPoints = (int)Math.Floor((double)m / 2.0);
int[] rowCutPoints = new int[numRowCutPoints];
int[] colCutPoints = new int[numColCutPoints];
// Perform row-wise crossovers
for (int y = 1; y < m; ++y)
{
rowCutPoints[0] = Math.Abs(s1[y - 1] - s1[y]) % m;
for (int k = 1; k < numRowCutPoints; ++k)
{
rowCutPoints[k] = (rowCutPoints[k - 1]
+ Math.Abs(s1[y - 1] - s1[y])) % m;
}
Array.Sort(rowCutPoints);
for (int k = 1; k < numRowCutPoints; ++k)
{
for (int x = rowCutPoints[k - 1]; x < rowCutPoints[k]; ++x)
{
// Swap the pixels.
Color pix1 = CiphertextImage.GetPixel(x, s1[y]);
Color pix2 = CiphertextImage.GetPixel(x, s1[y - 1]);
CiphertextImage.SetPixel(x, s1[y], pix2);
CiphertextImage.SetPixel(x, s1[y - 1], pix1);
}
}
} // End row-wise crossovers.
// Perform column-wise crossovers
for (int x = 1; x < n; ++x)
{
colCutPoints[0] = Math.Abs(s2[x - 1] - s2[x]) % n;
for (int k = 1; k < numColCutPoints; ++k)
{
colCutPoints[k] = (colCutPoints[k - 1]
+ Math.Abs(s2[x - 1] - s2[x])) % n;
}
Array.Sort(colCutPoints);
for (int k = 1; k < numColCutPoints; ++k)
{
for (int y = colCutPoints[k - 1]; y < colCutPoints[k]; ++y)
{
// Swap the pixels.
Color pix1 = CiphertextImage.GetPixel(s2[x], y);
Color pix2 = CiphertextImage.GetPixel(s2[x - 1], y);
CiphertextImage.SetPixel(s2[x], y, pix2);
CiphertextImage.SetPixel(s2[x - 1], y, pix1);
}
}
} // End column-wise crossovers.
} // End method Crossover().
/**************************************************
* Public Methods *
**************************************************/
/// <summary>
/// Encrypt the plaintext image with the given key.
/// </summary>
public void Encrypt()
{
// Make sure we have a key!
if (Key == null)
{
throw new System.ArgumentException(
"The key has not been instantiated.");
}
// Ensure that a plaintext image is available for encryption.
if (PlaintextImage == null)
{
throw new System.NullReferenceException(
"The plaintext image is not defined.");
}
// We need to ensure that the plaintext image is grayscale.
PlaintextImage = GrayScale(
PlaintextImage.Clone(new Rectangle(0, 0,
PlaintextImage.Width, PlaintextImage.Height),
System.Drawing.Imaging.PixelFormat.Format24bppRgb));
// Ensure that we have a 24bpp image to work with since SetPixel()
// won't work with an indexed image.
CiphertextImage = PlaintextImage.Clone(
new Rectangle(0, 0,
PlaintextImage.Width, PlaintextImage.Height),
System.Drawing.Imaging.PixelFormat.Format24bppRgb);
int [,] schedule = GenerateStateSchedule(Key.Seed);
int [] attractorRing = MakeAttractorRing(Key.StateOne, Key.Rule);
int lum = 0; // The luminance value of a given pixel.
int stateIndex = 0;
for (int y = 0; y < PlaintextImage.Height; ++y)
{
for (int x = 0; x < PlaintextImage.Width; ++x)
{
// Since the image is grayscale we only need
// one channel's data.
lum = PlaintextImage.GetPixel(x, y).ToArgb() & 0x000000ff;
// Jin recommends each pixel's starting state use the
// attractor ring index (x + y) mod 8.
stateIndex = (x + y) % 8;
lum ^= attractorRing[stateIndex];
// This provides the avalanche effect.
for (int i = 0; i < schedule[x, y]; ++i)
{
stateIndex = (++stateIndex) % 8;
lum ^= attractorRing[stateIndex];
}
// Write the pixel data to the ciphertext image.
CiphertextImage.SetPixel(
x, y, Color.FromArgb(0xff, lum, lum, lum));
}
}
} // End method Encrypt().
