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));
}
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]);
}