public static Polinom PowerGF256(Polinom a, Polinom b, byte f)
{
byte c = 1;
byte bc = b.coef;
while (bc > 0)
{
if (bc % 2 == 1)
{
c = MultGF256(a, b, f).coef;
}
a = MultGF256(a, a, f);
bc = (byte)(bc >> 1);
}
return(new Polinom(c));
}
public static Polinom MultGF256(Polinom a, Polinom b, byte f)
{
byte t = 0, mask = 1;
byte ac = a.coef, bc = b.coef;
for (int i = 0; i < 8; i++)
{
if ((bc & mask) != 0)
{
t = (byte)(t ^ ac);
}
if ((ac & 128) != 0)
{
ac = (byte)(ac << 1);
}
else
{
ac = (byte)((ac << 1) ^ f);
}
mask = (byte)(mask << 1);
}
return(new Polinom(t));
}
