private static BitArray ApplyKey(BitArray input, BitArray key)
{
var e = input.ApplyPermutation(E_SELECT);
var xor = e.Xor(key);
var output = new BitArray(32);
for (int i = 0; i < 8; i++)
{
var bits = xor.SubArray(i * 6, 6);
output.Insert(i * 4, SBoxEnumerator.Enumerate(bits, i));
}
return(output.ApplyPermutation(P));
}
private static BitArray EncryptDecryptBlock(BitArray block, List <BitArray> keys)
{
var ip = block.ApplyPermutation(IP);
int mid = ip.Count / 2;
var left = ip.SubArray(0, mid);
var right = ip.SubArray(mid, mid);
for (int i = 0; i < 16; i++)
{
var temp = left;
left = right;
right = temp.Xor(ApplyKey(right, keys[i]));
}
var concat = right.Concat(left);
return(concat.ApplyPermutation(IP_INVERSE));
}
public static List <BitArray> GetKeyPermutations(BitArray key)
{
var pc1 = key.ApplyPermutation(PC_1);
int mid = pc1.Count / 2;
var left = pc1.SubArray(0, mid);
var right = pc1.SubArray(mid, mid);
var keys = new List <BitArray>();
for (int i = 0; i < 16; i++)
{
left = left.ShiftLeft(ShiftCounts[i]);
right = right.ShiftLeft(ShiftCounts[i]);
var concat = left.Concat(right);
var pc2 = concat.ApplyPermutation(PC_2);
keys.Add(pc2);
}
return(keys);
}