说明：  实现椭圆曲线加密算法，椭圆曲线参数选取为160个比特，实现大数类，实现椭圆曲线的倍加倍乘运算
(Realization of elliptic curve cryptography, elliptic curve parameter selection is 160 bits, to achieve large numbers category, achieving the elliptic curve doubling times multiplication)