用openssl密码库实现对称加密解密算法DES、AES

使用 OpenSSL 库实现对称加密解密算法 DES 和 AES 的步骤如下：

1. 引入 OpenSSL 库头文件和链接库：

#include <openssl/des.h>
#include <openssl/aes.h>
// 链接库需要添加 -lcrypto 参数

2. 生成密钥：

DES_cblock key_des;
DES_random_key(&key_des);

unsigned char key_aes[AES_BLOCK_SIZE];
RAND_bytes(key_aes, AES_BLOCK_SIZE);

3. 初始化加密解密上下文：

DES_key_schedule schedule;
DES_set_key(&key_des, &schedule);

AES_KEY key_aes;
AES_set_encrypt_key(key_aes, 128, &key_aes);
AES_set_decrypt_key(key_aes, 128, &key_aes);

4. 加密解密数据：

DES_encrypt1(input, output, &schedule);
DES_decrypt1(input, output, &schedule);

AES_encrypt(input, output, &key_aes);
AES_decrypt(input, output, &key_aes);

完整的示例代码如下所示：

#include <openssl/des.h>
#include <openssl/aes.h>
#include <openssl/rand.h>
#include <stdio.h>
#include <string.h>

int main()
{
    // DES加密解密
    DES_cblock key_des;
    DES_random_key(&key_des);
    unsigned char input_des[] = "Hello, world!";
    unsigned char output_des[32];
    DES_key_schedule schedule;
    DES_set_key(&key_des, &schedule);
    DES_encrypt1(input_des, output_des, &schedule);
    DES_decrypt1(output_des, input_des, &schedule);
    printf("DES decrypted message: %s\n", input_des);

    // AES加密解密
    unsigned char key_aes[AES_BLOCK_SIZE];
    RAND_bytes(key_aes, AES_BLOCK_SIZE);
    unsigned char input_aes[] = "Hello, world!";
    unsigned char output_aes[32];
    AES_KEY aes_key;
    AES_set_encrypt_key(key_aes, 128, &aes_key);
    AES_encrypt(input_aes, output_aes, &aes_key);
    AES_set_decrypt_key(key_aes, 128, &aes_key);
    AES_decrypt(output_aes, input_aes, &aes_key);
    printf("AES decrypted message: %s\n", input_aes);

    return 0;
}