使用c语言实现DH秘钥分配算法
DH算法原理
密钥分配
-
- 选择一个大素数p， 选择一个整数g(g < p)；
- 通信方A选择一个随机数a，并发送
mod p 给 通信方B； - 通信方B选择一个随机数b，并发送
mod p 给 通信方A； - 通信方A计算k1 = (
mod p)a mod p； - 通信方B计算k2 = (
mod p)b mod p； - 由此，k1 = k2。
DH.h
#pragma once
#include <tommath.h>
#include <time.h>
#include <iostream>
#include <Windows.h>using namespace std;#define SUBKEY_LENGTH 78 // >512 bitvoid Create_number(mp_int *number, int mode);
int Miller_rabin(mp_int *number);
void Create_prime_number(mp_int *number);
void initial();
void mp_print(mp_int *number);
void Write_num_2_File(char *file_name, mp_int *num);
DH.cpp
#include "DH.h"mp_int two;
mp_int five;
mp_int zero;
mp_int one;void Create_number(mp_int *number, int mode)
{int i;srand((unsigned)time(NULL));char temp_number[SUBKEY_LENGTH + 1];temp_number[0] = rand() % 9 + 1 + 48;if (0 == mode){int temp;for (i = 1; i <= SUBKEY_LENGTH - 2; i++)temp_number[i] = rand() % 10 + 48;temp = rand() % 10;if (0 == temp % 2)temp++;if (5 == temp)temp = 7;temp_number[SUBKEY_LENGTH - 1] = temp + 48;temp_number[SUBKEY_LENGTH] = '\0';}else if (1 == mode){int digit = rand() % (SUBKEY_LENGTH - 2) + 2;for (i = 1; i <= digit - 1; i++)temp_number[i] = rand() % 10 + 48;temp_number[digit] = '\0';}mp_read_radix(number, temp_number, 10);
}int Miller_rabin(mp_int *number)
{int result;mp_int base;mp_init_size(&base, SUBKEY_LENGTH);Create_number(&base, 1);mp_prime_miller_rabin(number, &base, &result);mp_clear(&base);return result;
}void Create_prime_number(mp_int *number)
{mp_int r;mp_init(&r);int time = 100;int result;int i;Create_number(number, 0);while (1){mp_prime_is_divisible(number, &result);if (0 != result){do{mp_add(number, &two, number);mp_mod(number, &five, &r);} while (MP_EQ == mp_cmp_mag(&zero, &r));continue;}for (i = 0; i < time; i++){if (!Miller_rabin(number))break;}if (i == time)return;else{do{mp_add(number, &two, number);mp_mod(number, &five, &r);} while (MP_EQ == mp_cmp_mag(&zero, &r));}}
}void initial()
{mp_init_set_int(&two, 2);mp_init_set_int(&five, 5);mp_init_set_int(&zero, 0);mp_init_set_int(&one, 1);
}void mp_print(mp_int *number)
{char str[SUBKEY_LENGTH * 2 + 1];mp_toradix(number, str, 10);cout << str << endl;
}void Write_num_2_File(char *file_name, mp_int *num)
{remove(file_name);FILE *fp = fopen(file_name, "w+");if (NULL == fp){cout << "open file error!" << endl;return;}char str[SUBKEY_LENGTH * 2];mp_toradix(num, str, 10);fprintf(fp, "%s", str);fclose(fp);
}
main.h
#pragma once
#include "DH.h"
main.cpp
#include "main.h"int main()
{initial();mp_int p, g, a, b, ka, kb;mp_init_size(&p, SUBKEY_LENGTH);mp_init_size(&g, SUBKEY_LENGTH);mp_init_size(&a, SUBKEY_LENGTH);mp_init_size(&b, SUBKEY_LENGTH);mp_init_size(&ka, SUBKEY_LENGTH);mp_init_size(&kb, SUBKEY_LENGTH);Create_prime_number(&p);Create_number(&g, 1);Sleep(1000);Create_number(&a, 1);Sleep(1000);Create_number(&b, 1);mp_exptmod(&g, &a, &p, &ka);mp_exptmod(&g, &b, &p, &kb);cout << "p: ";mp_print(&p);cout << "g: ";mp_print(&g);cout << "a: ";mp_print(&a);cout << "b: ";mp_print(&b);cout << "ka: ";mp_print(&ka);cout << "kb: ";mp_print(&kb);Write_num_2_File("d:\\DH_p.txt", &p);Write_num_2_File("d:\\DH_g.txt", &g);Write_num_2_File("d:\\DH_a.txt", &a);Write_num_2_File("d:\\DH_b.txt", &b);Write_num_2_File("d:\\DH_ka.txt", &ka);Write_num_2_File("d:\\DH_kb.txt", &kb);mp_clear_multi(&p, &g, &a, &b, &ka, &kb, NULL);return 0;
}
