public ECC521Point Multiply(BigInteger b)
{
if (b.Sign == -1)
{
throw new FormatException("The multiplicator cannot be negative");
}
if (b >= OrderN)
{
b %= OrderN;
}
BigInteger exp = (b * 3) ^ b;
ECC521Point result = ECC521Point.Infinity;
ECC521Point affine = this.Normalize();
ECC521Point negative = affine.Negate();
int high = exp <= 0 ? 0 : (int)Math.Floor(BigInteger.Log(exp, 2));
BigInteger bit = BigInteger.One << high;
for (int i = high; --i >= 0; bit >>= 1)
{
result = result.Twice();
if (!(exp & bit).IsZero)
{
result = result.Add(!(b & bit).IsZero ? negative : affine);
}
}
result = result.Normalize();
return(result);
}
public ECC521Point Subtract(ECC521Point b)
{
return(Add(b.Negate()));
}
