finite-field arithmetic

The idea of the fast method is independent on the optimization of finite field arithmetic and the choice of coordinate expression of points of elliptic curves.
實現了算法的快速優化，其原理與有限域算術優化和橢圓曲線點的坐標表示的選取無關，其運算速度是通常的重複加倍—點加算法的6倍。