Halves Split56(ulong block)
{
Halves splitBlock = new Halves();
splitBlock.Left = block >> (64 - 28) << (64 - 28);
splitBlock.Right = block << 28;
return(splitBlock);
}
Halves Split64(ulong block)
{
Halves splitBlock = new Halves();
splitBlock.Left = block >> 32 << 32;
splitBlock.Right = block << 32;
return(splitBlock);
}
// Takes original key and generates all 16 keys.
void GenerateKeys(ulong key)
{
ulong pc1Key = Permute(key, ref permChoice1Table);
Halves keyHalves = Split56(pc1Key);
for (int i = 0; i < 16; i++)
{
keyHalves.Left = LeftShift56(keyHalves.Left, LeftShifts[i]);
keyHalves.Right = LeftShift56(keyHalves.Right, LeftShifts[i]);
ulong newKey = Merge(keyHalves);
keys[i] = Permute(newKey, ref permChoice2Table);
}
}
public override string Encrypt(string plainText, string key)
{
ulong plainBlock = Convert.ToUInt64(plainText, 16); // Convert Hex string to 64 bits number
ulong plainKey = Convert.ToUInt64(key, 16);
GenerateKeys(plainKey);
ulong initialPermBlock = Permute(plainBlock, ref initialPermTable);
Halves halves = Split64(initialPermBlock);
for (int i = 0; i < 16; i++)
{
halves = Round(halves, keys[i]);
}
ulong swapped = halves.Right | (halves.Left >> 32);
ulong final = Permute(swapped, ref inverseInitialPermTable);
return("0x" + final.ToString("X").PadLeft(16, '0'));
}
Halves Round(Halves block, ulong key)
{
ulong expandedRightHalf = Permute(block.Right, ref expansionTable);
ulong nextRight = expandedRightHalf ^ key;
byte[] sboxesInput = SplitIntoEight(nextRight); // split 48 bits into 8 groups of 6-bits
ulong sBoxesRes = 0;
for (int i = 0; i < 8; i++)
{
sBoxesRes <<= 4;
sBoxesRes |= FromSBox(sboxesInput[i], i);
}
sBoxesRes <<= 32;
nextRight = Permute(sBoxesRes, ref permutationTable);
nextRight ^= block.Left;
ulong nextLeft = block.Right;
return(new Halves {
Left = nextLeft, Right = nextRight
});
}
ulong Merge(Halves halves)
{
return((halves.Left & 0xFFFFFFF000000000) | ((halves.Right & 0xFFFFFFF000000000) >> 28));
}
