public MatrixInt DecryptMessage(MatrixInt encryptedMessage)
{
var message = encryptedMessage.Clone();
#region Unmask
for (int col = 0; col < message.ColumnCount; col++)
{
for (int row = 0; row < message.RowCount; row++)
{
message[row, col] = LinearCode.GaloisField.MultiplyWords(message[row, col], LinearCode.GaloisField.GetMultiplicativeInverse(PrivateKey.Mask[col]));
}
}
#endregion
//Debug.WriteLine(message);
#region Inverse permutation
var inversePermutation = Helper.InversePermutation(PrivateKey.Permutation);
message = message.PermuteColumns(inversePermutation);
#endregion
//Debug.WriteLine(message);
#region Correct Errors
var correctedMessage = LinearCode.DecodeAndCorrect(message);
#endregion
//Debug.WriteLine(correctedMessage);
#region Apply the inverse scrambler matrix
var inverseScramblerMatrix = MatrixAlgorithms.MatrixInverse(PrivateKey.ScramblerMatrix, LinearCode.GaloisField);
var decryptedMessage = MatrixAlgorithms.DotMultiplication(correctedMessage, inverseScramblerMatrix, LinearCode.GaloisField);
#endregion
return(decryptedMessage);
}
public McElieseEllyptic(int n, int k, int d, int t, GaloisField galoisField, MatrixInt scramblerMatrix = null, IList <int> permutation = null, IList <int> mask = null)
{
_generator = new ParityCheckMatrixGeneratorEllyptic(2);
LinearCode = new LinearCode(n, k, d, t, galoisField);
MatrixInt parityCheckMatrix = null;
MatrixInt generatorMatrix = null;
while (true)
{
parityCheckMatrix = _generator.Generate(LinearCode);
LinearCode.ParityCheckMatrix = parityCheckMatrix;
Debug.WriteLine(parityCheckMatrix);
var minValueFillPercentage = 0.7;
if (Helper.Weight(parityCheckMatrix) < Math.Ceiling(parityCheckMatrix.RowCount * parityCheckMatrix.ColumnCount * minValueFillPercentage))
{
continue;
}
try
{
generatorMatrix = GeneratorMatrixCalculator.CalculateGeneratorMatrixAlt(LinearCode);
Debug.WriteLine(generatorMatrix);
}
catch (LinearCodeException ex)
{
Debug.WriteLine(ex.Message);
continue;
}
if (IsGeneratorMatrixValid(parityCheckMatrix, generatorMatrix, galoisField))
{
LinearCode.GeneratorMatrix = generatorMatrix;
break;
}
}
if (scramblerMatrix is null)
{
scramblerMatrix = Helper.GenerateScramblerMatrix(LinearCode.K);
while (true)
{
try
{
MatrixAlgorithms.MatrixInverse(scramblerMatrix, galoisField);
break;
}
catch (SolveMatrixException)
{
Debug.WriteLine("Reattempting to generate scrambler matrix");
}
}
}
if (permutation is null)
{
permutation = Helper.GeneratePermutaionList(LinearCode.N);
}
if (mask is null)
{
mask = Helper.GenerateMask(LinearCode.N, LinearCode.GaloisField);
}
var inverseMask = new List <int>(LinearCode.N);
for (int i = 0; i < LinearCode.N; i++)
{
inverseMask.Add(LinearCode.GaloisField.GetMultiplicativeInverse(mask[i]));
}
PrivateKey = new PrivateKey
{
GeneratorMatrix = LinearCode.GeneratorMatrix,
ScramblerMatrix = scramblerMatrix,
InverseScramblerMatrix = MatrixAlgorithms.MatrixInverse(scramblerMatrix, galoisField),
Permutation = permutation,
InversePermutation = Helper.InversePermutation(permutation),
Mask = mask,
InverseMask = inverseMask
};
var encryptionMatrix = MatrixAlgorithms.DotMultiplication(PrivateKey.ScramblerMatrix, generatorMatrix, LinearCode.GaloisField);
Debug.WriteLine(encryptionMatrix);
encryptionMatrix = encryptionMatrix.PermuteColumns(PrivateKey.Permutation);
Debug.WriteLine(encryptionMatrix);
for (int col = 0; col < encryptionMatrix.ColumnCount; col++)
{
for (int row = 0; row < encryptionMatrix.RowCount; row++)
{
encryptionMatrix[row, col] = LinearCode.GaloisField.MultiplyWords(encryptionMatrix[row, col], PrivateKey.Mask[col]);
}
}
Debug.WriteLine(encryptionMatrix);
PublicKey = new PublicKey
{
EncryptionMatrix = encryptionMatrix,
};
}