PointGFp EC_Group::point_multiply(const BigInt& x, const PointGFp& pt, const BigInt& y) const
   {
   PointGFp_Multi_Point_Precompute xy_mul(get_base_point(), pt);
   return xy_mul.multi_exp(x, y);
   }
PointGFp EC_Group::point_multiply(const BigInt& x, const PointGFp& pt, const BigInt& y) const
   {
   PointGFp_Multi_Point_Precompute xy_mul(get_base_point(), pt);
   return xy_mul.multi_exp(x, y);
   }