一个 Linux下非对称加密demo，ubuntu18.04验证通过

[ubuntu]

生成密钥对：

openssl genrsa -out private_key.pem 2048
openssl rsa -in private_key.pem -outform PEM -pubout -out public_key.pem

#include <stdio.h>
#include <string.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>

int main() {
    // 加载RSA密钥对
    RSA *rsa_keypair = RSA_new();
    FILE *private_key_file = fopen("private_key.pem", "r");
    PEM_read_RSAPrivateKey(private_key_file, &rsa_keypair, NULL, NULL);
    fclose(private_key_file);

    // 加载公钥
    RSA *rsa_public_key = RSA_new();
    FILE *public_key_file = fopen("public_key.pem", "r");
    PEM_read_RSA_PUBKEY(public_key_file, &rsa_public_key, NULL, NULL);
    fclose(public_key_file);

    // 明文数据
    char *plaintext = "Hello, world!";

    // 分配内存保存加密后的数据
    int plaintext_len = strlen(plaintext);
    int encrypted_len = RSA_size(rsa_public_key);
    unsigned char *encrypted_data = (unsigned char *)malloc(encrypted_len);

    // 加密数据
    int result = RSA_public_encrypt(plaintext_len, (unsigned char *)plaintext,
            encrypted_data, rsa_public_key, RSA_PKCS1_PADDING);
    if (result == -1) {
        printf("Error: RSA_public_encrypt failed!\n");
        return -1;
    }

    // 输出加密后的数据
    printf("Encrypted data: ");
    for (int i = 0; i < result; i++) {
        printf("%02x", encrypted_data[i]);
    }
    printf("\n");

    // 分配内存保存解密后的数据
    int decrypted_len = RSA_size(rsa_keypair);
    unsigned char *decrypted_data = (unsigned char *)malloc(decrypted_len);

    // 解密数据
    result = RSA_private_decrypt(encrypted_len, encrypted_data, decrypted_data,
            rsa_keypair, RSA_PKCS1_PADDING);
    if (result == -1) {
        printf("Error: RSA_private_decrypt failed!\n");
        return -1;
    }

    // 输出解密后的数据
    printf("Decrypted data: %s\n", decrypted_data);

    // 释放内存
    free(encrypted_data);
    free(decrypted_data);
    RSA_free(rsa_keypair);
    RSA_free(rsa_public_key);

    return 0;
}

编译指令：

gcc -o rsa_example rsa_example.c -lcrypto

运行：

./rsa_example
Encrypted data: 831bbcc94a2f5b30b605849d4756273b7d88d4995f2a2688f26aab81ef3ab992e7fcebe0530e8c0d5c4f889313648f319d55e2321d48edec4e1760959ca24b168               2d0e06911c3e1f8e94357f10b88f2fd6a0e3b1978a8ce6252de849d410f36b1123d7a4a66913eb1bd6c8096fb80f15bda150530a77f6aace39008f35bf7873d11a4903fa0d97647a6               18630b7781732a81d72e17771c60cf343b18565f1e49422dcd2de33cb4f18693a1def0c9b029ec6d1b96991bde6e55b3bdd972391df3c403c13fe27b38df75b4aeb963ad34cd0d55b               26f810d0735017c0e93da288c12bcf71a9b08cacee9923843a506585b534b484ef63119fe813dbf90b9c85fd707ef
Decrypted data: Hello, world!