public FastECPoint Multiply(FastInteger b)
{
if (b.Sign == -1)
{
throw new FormatException("The multiplicator cannot be negative");
}
//b = b % Secp256k1.N;
FastInteger exp = (b * 3) ^ b;
FastECPoint result = FastECPoint.Infinity;
FastECPoint affine = this.Normalize();
FastECPoint negative = affine.Negate();
int high = exp.BitsCount;
FastInteger bit = FastInteger.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 FastECPoint Subtract(FastECPoint b)
{
return(Add(b.Negate()));
}