dsa 数字签名算法代码实现基于c++
时间: 2023-08-17 07:15:18 浏览: 282
以下是DSA算法的C++实现示例:
```cpp
#include <iostream>
#include <random>
#include <cstring>
#include <openssl/sha.h>
#include <openssl/bn.h>
using namespace std;
// 生成质数p和q
void gen_p_q(int L, int N, BIGNUM* p, BIGNUM* q)
{
int n = (L - 1) / N;
int b = (L - 1) % N;
BIGNUM* seed = BN_new();
BN_set_bit(seed, N - 1);
BN_set_bit(seed, 0);
while (1) {
// 生成大质数q
BN_generate_prime_ex(q, N, 0, seed, NULL, NULL);
// 生成大质数p
int i = 0;
while (i < 4 * L) {
BIGNUM* V[n + 1];
for (int k = 0; k <= n; k++) {
V[k] = BN_new();
}
BN_rand(V[0], b - 1, 0);
BN_set_bit(V[0], b - 1);
for (int k = 1; k < n; k++) {
BN_rand(V[k], N - 1, 0);
}
BN_rand(V[n], b, 0);
BN_set_bit(V[n], N - 1);
BIGNUM* X = BN_new();
BN_set_word(X, 0);
for (int k = n; k >= 0; k--) {
BN_lshift(X, X, N);
BN_add(X, X, V[k]);
}
BN_add_word(X, 1);
if (BN_mod(X, X, q, NULL) != 0 && BN_is_prime_fasttest_ex(X, 10, NULL, 0, NULL)) {
BN_copy(p, X);
break;
}
i++;
}
if (BN_num_bits(p) == L) {
break;
}
}
}
// 计算a^b mod n
void pow_mod(BIGNUM* a, BIGNUM* b, BIGNUM* n, BIGNUM* res)
{
BN_CTX* ctx = BN_CTX_new();
BN_mod_exp(res, a, b, n, ctx);
BN_CTX_free(ctx);
}
// 生成密钥对
void gen_key(BIGNUM* p, BIGNUM* q, BIGNUM* g, BIGNUM* x, BIGNUM* y)
{
BN_rand_range(x, q);
pow_mod(g, x, p, y);
}
// 签名
void sign(string msg, BIGNUM* p, BIGNUM* q, BIGNUM* g, BIGNUM* x, BIGNUM* r, BIGNUM* s)
{
BIGNUM* k = BN_new();
BIGNUM* H = BN_new();
BN_CTX* ctx = BN_CTX_new();
BN_bin2bn((unsigned char*)msg.c_str(), msg.length(), H);
SHA1((unsigned char*)msg.c_str(), msg.length(), (unsigned char*)H);
while (1) {
BN_rand_range(k, q);
pow_mod(g, k, p, r);
BN_mod_mul(s, x, r, q, ctx);
BN_mod_add(s, s, H, q, ctx);
BN_mod_mul(s, s, BN_mod_inverse(k, q, ctx), q, ctx);
if (!BN_is_zero(s)) {
break;
}
}
BN_free(k);
BN_free(H);
BN_CTX_free(ctx);
}
// 验证签名
bool verify(string msg, BIGNUM* p, BIGNUM* q, BIGNUM* g, BIGNUM* y, BIGNUM* r, BIGNUM* s)
{
BIGNUM* H = BN_new();
BN_CTX* ctx = BN_CTX_new();
BN_bin2bn((unsigned char*)msg.c_str(), msg.length(), H);
SHA1((unsigned char*)msg.c_str(), msg.length(), (unsigned char*)H);
BIGNUM* w = BN_new();
BN_mod_inverse(w, s, q, ctx);
BIGNUM* u1 = BN_new();
BIGNUM* u2 = BN_new();
BN_mod_mul(u1, H, w, q, ctx);
BN_mod_mul(u2, r, w, q, ctx);
BIGNUM* v1 = BN_new();
BIGNUM* v2 = BN_new();
pow_mod(g, u1, p, v1);
pow_mod(y, u2, p, v2);
BN_mod_mul(v1, v1, v2, p, ctx);
BN_mod(v1, v1, q, ctx);
BN_free(H);
BN_free(w);
BN_free(u1);
BN_free(u2);
BN_free(v1);
BN_free(v2);
BN_CTX_free(ctx);
return BN_cmp(v1, r) == 0;
}
int main()
{
int L = 1024;
int N = 160;
BIGNUM* p = BN_new();
BIGNUM* q = BN_new();
gen_p_q(L, N, p, q);
BIGNUM* g = BN_new();
BIGNUM* x = BN_new();
BIGNUM* y = BN_new();
BN_set_word(g, 2);
gen_key(p, q, g, x, y);
BIGNUM* r = BN_new();
BIGNUM* s = BN_new();
sign("hello, world", p, q, g, x, r, s);
cout << "signature: r=" << BN_bn2dec(r) << ", s=" << BN_bn2dec(s) << endl;
if (verify("hello, world", p, q, g, y, r, s)) {
cout << "verify signature success" << endl;
} else {
cout << "verify signature failed" << endl;
}
BN_free(p);
BN_free(q);
BN_free(g);
BN_free(x);
BN_free(y);
BN_free(r);
BN_free(s);
return 0;
}
```
其中,gen_p_q函数用于生成大素数p和q,gen_key函数用于生成密钥对,sign函数用于签名,verify函数用于验证签名。需要注意的是,在实际应用中,还需要对消息进行哈希处理,以保证签名长度不会过长。另外,需要使用OpenSSL的BIGNUM库进行大整数计算。
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