private static byte[][] MixColumns(byte[][] s)
{
int[] sp = new int[4];
byte b02 = (byte)0x02,
b03 = (byte)0x03;
for (int c = 0; c < 4; c++)
{
sp[0] = AESFeistel.FFMul(b02, s[0][c]) ^ AESFeistel.FFMul(b03, s[1][c]) ^ s[2][c] ^ s[3][c];
sp[1] = s[0][c] ^ AESFeistel.FFMul(b02, s[1][c]) ^ AESFeistel.FFMul(b03, s[2][c]) ^ s[3][c];
sp[2] = s[0][c] ^ s[1][c] ^ AESFeistel.FFMul(b02, s[2][c]) ^ AESFeistel.FFMul(b03, s[3][c]);
sp[3] = AESFeistel.FFMul(b03, s[0][c]) ^ s[1][c] ^ s[2][c] ^ AESFeistel.FFMul(b02, s[3][c]);
for (int i = 0; i < 4; i++)
{
s[i][c] = (byte)(sp[i]);
}
}
return(s);
}
private static byte[][] InvMixColumns(byte[][] s)
{
int[] sp = new int[4];
byte b02 = (byte)0x0e,
b03 = (byte)0x0b,
b04 = (byte)0x0d,
b05 = (byte)0x09;
for (int c = 0; c < 4; c++)
{
sp[0] = AESFeistel.FFMul(b02, s[0][c]) ^ AESFeistel.FFMul(b03, s[1][c]) ^ AESFeistel.FFMul(b04, s[2][c]) ^ AESFeistel.FFMul(b05, s[3][c]);
sp[1] = AESFeistel.FFMul(b05, s[0][c]) ^ AESFeistel.FFMul(b02, s[1][c]) ^ AESFeistel.FFMul(b03, s[2][c]) ^ AESFeistel.FFMul(b04, s[3][c]);
sp[2] = AESFeistel.FFMul(b04, s[0][c]) ^ AESFeistel.FFMul(b05, s[1][c]) ^ AESFeistel.FFMul(b02, s[2][c]) ^ AESFeistel.FFMul(b03, s[3][c]);
sp[3] = AESFeistel.FFMul(b03, s[0][c]) ^ AESFeistel.FFMul(b04, s[1][c]) ^ AESFeistel.FFMul(b05, s[2][c]) ^ AESFeistel.FFMul(b02, s[3][c]);
for (int i = 0; i < 4; i++)
{
s[i][c] = (byte)(sp[i]);
}
}
return(s);
}