Are these two functions the same?
- by Ranhiru
There is a function in the AES algorithm, to multiply a byte by 2 in Galois Field.
This is the function given in a website
private static byte gfmultby02(byte b)
{
if (b < 0x80)
return (byte)(int)(b <<1);
else
return (byte)( (int)(b << 1) ^ (int)(0x1b) );
}
This is the function i wrote.
private static byte MulGF2(byte x)
{
if (x < 0x80)
return (byte)(x << 1);
else
{
return (byte)((x << 1) ^ 0x1b);
}
}
What i need to know is, given any byte whether this will perform in the same manner. Actually I am worried about the extra conversion of to int and then again to byte. So far I have tested and it looks fine. Does the extra cast to int and then to byte make a difference?
