c++实现椭圆曲线密码算法
时间: 2023-08-18 19:08:05 浏览: 265
椭圆曲线密码算法(Elliptic Curve Cryptography,ECC)是一种公钥加密算法,可以用于数据加密和数字签名等安全应用。以下是C++实现椭圆曲线密码算法的示例代码:
```cpp
#include <iostream>
#include <string>
#include <vector>
#include <NTL/ZZ.h> // NTL库提供的大数运算
using namespace std;
using namespace NTL;
// 定义椭圆曲线参数
ZZ p("0xfffffffffffffffffffffffffffffffeffffffffffffffff");
ZZ a("-0x3");
ZZ b("0x5");
ZZ n("0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141");
// 定义椭圆曲线点结构体
struct ECPoint {
ZZ x;
ZZ y;
};
// 判断两个大整数是否相等
bool isEqual(const ZZ& a, const ZZ& b) {
return (a == b);
}
// 判断椭圆曲线点是否为无穷远点
bool isInfinity(const ECPoint& P) {
return (P.x == 0 && P.y == 0);
}
// 判断椭圆曲线点是否在椭圆曲线上
bool isOnCurve(const ECPoint& P) {
ZZ y2 = SqrMod(P.y, p);
ZZ x3 = SqrMod(P.x, p) * P.x % p;
ZZ ax = a * P.x % p;
ZZ bmodp = b % p;
ZZ x3_ax = (x3 + ax) % p;
ZZ x3_ax_b = (x3_ax + bmodp) % p;
return isEqual(y2, x3_ax_b);
}
// 计算两个椭圆曲线点之和
ECPoint add(const ECPoint& P, const ECPoint& Q) {
if (isInfinity(P)) return Q;
if (isInfinity(Q)) return P;
if (isEqual(P.x, Q.x) && isEqual(P.y, Q.y)) {
ZZ tmp1 = SqrMod(P.x, p);
ZZ tmp2 = (tmp1 << 1) % p;
ZZ tmp3 = (tmp2 + tmp1 + a) % p;
ZZ tmp4 = (P.y << 1) % p;
ZZ tmp5 = InvMod(tmp4, p);
ZZ tmp6 = (tmp3 * tmp5) % p;
ZZ x = (SqrMod(tmp6, p) - tmp2 - P.x - Q.x) % p;
ZZ y = ((tmp6 * (P.x - x) % p) - P.y) % p;
ECPoint R = {x, y};
return R;
} else {
ZZ tmp1 = (Q.y - P.y + p) % p;
ZZ tmp2 = (Q.x - P.x + p) % p;
ZZ tmp3 = InvMod(tmp2, p);
ZZ tmp4 = (tmp1 * tmp3) % p;
ZZ x = (SqrMod(tmp4, p) - P.x - Q.x + p + a) % p;
ZZ y = ((tmp4 * (P.x - x) % p) - P.y + p) % p;
ECPoint R = {x, y};
return R;
}
}
// 计算椭圆曲线点的k倍
ECPoint multiply(const ECPoint& P, const ZZ& k) {
ECPoint R = {0, 0};
ECPoint Q = P;
for (int i = NumBits(k) - 1; i >= 0; i--) {
R = add(R, R);
if (bit(k, i) == 1) {
R = add(R, Q);
}
}
return R;
}
int main() {
// 定义椭圆曲线点
ECPoint P = {0x4a96b5688ef573284664698968c38bb913cbfc82u, 0x23a628553168947d59dcc912042351377ac5fb32u};
// 定义私钥
ZZ d("0x1234567890abcdef");
// 计算公钥
ECPoint Q = multiply(P, d);
// 输出公钥
cout << "Public key: (" << Q.x << ", " << Q.y << ")" << endl;
return 0;
}
```
以上代码使用了NTL库提供的大数运算功能,可以在计算中使用任意大小的整数。在示例代码中,我们定义了椭圆曲线参数,包括模数p、系数a和b、点P以及阶n。接着,我们定义了椭圆曲线点结构体ECPoint,包含了点的x坐标和y坐标。我们实现了几个常用的椭圆曲线算法函数,包括判断两个大整数是否相等、判断椭圆曲线点是否为无穷远点、判断椭圆曲线点是否在椭圆曲线上、计算两个椭圆曲线点之和和计算椭圆曲线点的k倍。最后,我们使用示例代码计算了椭圆曲线公钥,并输出结果。
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