| static private LE_To_UInt32 ( byte bs ) : uint | ||
| bs | byte | |
| return | uint | |
/**
* Calculate the necessary round keys
* The number of calculations depends on key size and block size
* AES specified a fixed block size of 128 bits and key sizes 128/192/256 bits
* This code is written assuming those are the only possible values
*/
private uint[,] GenerateWorkingKey(
byte[] key,
bool forEncryption)
{
int KC = key.Length / 4; // key length in words
int t;
if ((KC != 4) && (KC != 6) && (KC != 8))
{
throw new ArgumentException("Key length not 128/192/256 bits.");
}
ROUNDS = KC + 6; // This is not always true for the generalized Rijndael that allows larger block sizes
var W = new uint[ROUNDS + 1, 4]; // 4 words in a block
//
// copy the key into the round key array
//
t = 0;
for (int i = 0; i < key.Length; t++)
{
W[t >> 2, t & 3] = Pack.LE_To_UInt32(key, i);
i += 4;
}
//
// while not enough round key material calculated
// calculate new values
//
int k = (ROUNDS + 1) << 2;
for (int i = KC; (i < k); i++)
{
uint temp = W[(i - 1) >> 2, (i - 1) & 3];
if ((i % KC) == 0)
{
temp = SubWord(Shift(temp, 8)) ^ rcon[(i / KC) - 1];
}
else if ((KC > 6) && ((i % KC) == 4))
{
temp = SubWord(temp);
}
W[i >> 2, i & 3] = W[(i - KC) >> 2, (i - KC) & 3] ^ temp;
}
if (!forEncryption)
{
for (int j = 1; j < ROUNDS; j++)
{
for (int i = 0; i < 4; i++)
{
W[j, i] = Inv_Mcol(W[j, i]);
}
}
}
return(W);
}
private void UnPackBlock(
byte[] bytes,
int off)
{
C0 = Pack.LE_To_UInt32(bytes, off);
C1 = Pack.LE_To_UInt32(bytes, off + 4);
C2 = Pack.LE_To_UInt32(bytes, off + 8);
C3 = Pack.LE_To_UInt32(bytes, off + 12);
}
