public Point Multiply(Point p, BigInteger scalar)
{
if (scalar <= 0)
{
throw new Exception("Cannot multiply by a scalar which is <= 0");
}
if (p == Point.POINT_AT_INFINITY)
{
return(Point.POINT_AT_INFINITY);
}
Point p1 = new Point(p.X, p.Y);
long high_bit = scalar.HighestBit() - 1;
// Double-and-add method
while (high_bit >= 0)
{
p1 = Add(p1, p1); // Double
if ((scalar.BitAt(high_bit)))
{
p1 = Add(p1, p); // Add
}
--high_bit;
}
return(p1);
}