rsa加解密算法c语言

RSA加解密算法是一种非对称加密算法，它的安全性基于大数分解的困难性。RSA算法的加密和解密过程都需要使用到公钥和私钥，其中公钥用于加密，私钥用于解密。下面是RSA加解密算法的C语言实现：

1. 生成公钥和私钥

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <math.h>

#define MAX_PRIME 1000000

int is_prime(int n) {
    if (n <= 1) {
        return 0;
    }
    for (int i = 2; i <= sqrt(n); i++) {
        if (n % i == 0) {
            return 0;
        }
    }
    return 1;
}

int gcd(int a, int b) {
    if (b == 0) {
        return a;
    }
    return gcd(b, a % b);
}

int main() {
    srand(time(NULL));
    int p, q, n, phi, e, d;
    do {
        p = rand() % MAX_PRIME + 1;
    } while (!is_prime(p));
    do {
        q = rand() % MAX_PRIME + 1;
    } while (!is_prime(q) || p == q);
    n = p * q;
    phi = (p - 1) * (q - 1);
    do {
        e = rand() % phi + 1;
    } while (gcd(e, phi) != 1);
    for (int i = 1; i < phi; i++) {
        if ((i * e) % phi == 1) {
            d = i;
            break;
        }
    }
    printf("Public key: (%d, %d)\n", e, n);
    printf("Private key: (%d, %d)\n", d, n);
    return 0;
}

2. 加密和解密

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int mod_pow(int base, int exponent, int modulus) {
    int result = 1;
    while (exponent > 0) {
        if (exponent % 2 == 1) {
            result = (result * base) % modulus;
        }
        base = (base * base) % modulus;
        exponent /= 2;
    }
    return result;
}

int main() {
    int e, d, n, len;
    char message[100];
    printf("Enter public key (e, n): ");
    scanf("%d %d", &e, &n);
    printf("Enter private key (d, n): ");
    scanf("%d %d", &d, &n);
    printf("Enter message to encrypt: ");
    scanf("%s", message);
    len = strlen(message);
    int encrypted[len], decrypted[len];
    for (int i = 0; i < len; i++) {
        encrypted[i] = mod_pow(message[i], e, n);
        decrypted[i] = mod_pow(encrypted[i], d, n);
    }
    printf("Encrypted message: ");
    for (int i = 0; i < len; i++) {
        printf("%d ", encrypted[i]);
    }
    printf("\nDecrypted message: ");
    for (int i = 0; i < len; i++) {
        printf("%c", decrypted[i]);
    }
    printf("\n");
    return 0;
}