private int Transform(int data, int firstSubkeyIdx, int secondSubkeyIdx)
{
int block = CombinatoricsUtil.Permutate(data, IP);
block = fK(block, subkeys[firstSubkeyIdx]);
block = SW(block);
block = fK(block, subkeys[secondSubkeyIdx]);
return(CombinatoricsUtil.Permutate(block, IIP));
}
private int F(int block, int subkey)
{
int extended = CombinatoricsUtil.Permutate(block, E) ^ subkey;
int[] parts = CombinatoricsUtil.Halve(extended, HALF_OF_BLOCK);
int left = S_BOXES[0][FindSBoxIndex(parts[0])];
int right = S_BOXES[1][FindSBoxIndex(parts[1])];
return(CombinatoricsUtil.Permutate((left << 2) | right, P4));
}
public void CheckSinglePermutate()
{
int expectedPermutatedResult = 290;
int input = 100;
int[] permutation = { 2, 4, 1, 6, 3, 9, 0, 8, 7, 5 };
int result = CombinatoricsUtil.Permutate(input, permutation);
Assert.AreEqual(expectedPermutatedResult, result);
}
public void CheckCyclicShiftToLeft()
{
int[] inputs = new int[] { 6, 15 };
int[] expects = new int[] { 12, 30 };
int numberOfShifts = 1;
int blockSize = 5;
for (int i = 0; i < inputs.Length; i++)
{
int result = CombinatoricsUtil.CyclicShiftToLeft(inputs[i], numberOfShifts, blockSize);
Assert.AreEqual(expects[i], result);
}
}
private int[] KeySchedule(int key)
{
int permutatedKey = CombinatoricsUtil.Permutate(key, P10);
int[] parts = CombinatoricsUtil.Halve(permutatedKey, HALF_OF_KEY);
int left = parts[0];
int right = parts[1];
subkeys = new int[2];
for (int i = 0; i < 2; i++)
{
left = CombinatoricsUtil.CyclicShiftToLeft(left, i + 1, HALF_OF_KEY);
right = CombinatoricsUtil.CyclicShiftToLeft(right, i + 1, HALF_OF_KEY);
subkeys[i] = CombinatoricsUtil.Permutate((left << HALF_OF_KEY) | right, P8);
}
return(subkeys);
}
private int fK(int block, int subkey)
{
int[] parts = CombinatoricsUtil.Halve(block, HALF_OF_BLOCK);
return((parts[0] ^ F(parts[1], subkey)) << HALF_OF_BLOCK | parts[1]);
}
private int SW(int x)
{
return(CombinatoricsUtil.CyclicShiftToLeft(x, 4, 8));
}
