Linux C openssl aes-128-cbc demo

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

#define AES_KEY_BITS 128
#define GCM_IV_SIZE 12
#define GCM_TAG_SIZE 16

int aes_cbc_encrypt(const unsigned char *plaintext,
        int plaintext_len, const unsigned char *aad,
        int aad_len, const unsigned char *key,
        unsigned char *ciphertext, unsigned char *tag)
{
   
   
    EVP_CIPHER_CTX *ctx = NULL;
    int len = 0;
    int ciphertext_len = 0;

    // 创建并初始化 EVP_CIPHER_CTX 对象
    ctx = EVP_CIPHER_CTX_new();
    EVP_EncryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, NULL, NULL);

    // 设置加密密钥
    EVP_EncryptInit_ex(ctx, NULL, NULL, key, NULL);

    // 加密明文数据
    if (EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len) > 0)
    {
   
   
        ciphertext_len = len;
    }
    else
    {
   
   
        printf("Error! \n");
    }

    // 结束加密过程，并生成认证标签
    EVP_EncryptFinal_ex(ctx, ciphertext + len, &len);
    ciphertext_len += len;
    EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, GCM_TAG_SIZE, tag);

    // 释放EVP_CIPHER_CTX对象
    EVP_CIPHER_CTX_free(ctx);

    return ciphertext_len;
}

int aes_cbc_decrypt(const unsigned char *ciphertext,
        int ciphertext_len, const