c语言实现 aes-128 cbc 加密

好的，下面是示例代码，使用 OpenSSL 库进行 AES-CBC 加密和解密：

加密：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/aes.h>

void aes_encrypt_cbc(const unsigned char *plaintext, int plaintext_len,
                     const unsigned char *key, const unsigned char *iv,
                     unsigned char *ciphertext) {
  AES_KEY aes_key;
  AES_set_encrypt_key(key, 128, &aes_key);
  AES_cbc_encrypt(plaintext, ciphertext, plaintext_len, &aes_key, iv, AES_ENCRYPT);
}

int main() {
  const unsigned char *plaintext = (const unsigned char *)"待加密的明文";
  const unsigned char *key = (const unsigned char *)"密钥";
  const unsigned char *iv = (const unsigned char *)"初始化向量";
  unsigned char ciphertext[AES_BLOCK_SIZE * ((strlen((const char *)plaintext) + AES_BLOCK_SIZE - 1) / AES_BLOCK_SIZE)];

  memset(ciphertext, 0, sizeof(ciphertext));
  aes_encrypt_cbc(plaintext, strlen((const char *)plaintext), key, iv, ciphertext);

  printf("加密结果：");
  for (int i = 0; i < sizeof(ciphertext); i++) {
    printf("%02x", ciphertext[i]);
  }
  printf("\n");

  return 0;
}

解密：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/aes.h>

void aes_decrypt_cbc(const unsigned char *ciphertext, int ciphertext_len,
                     const unsigned char *key, const unsigned char *iv,
                     unsigned char *plaintext) {
  AES_KEY aes_key;
  AES_set_decrypt_key(key, 128, &aes_key);
  AES_cbc_encrypt(ciphertext, plaintext, ciphertext_len, &aes_key, iv, AES_DECRYPT);
}

int main() {
  const unsigned char *ciphertext = (const unsigned char *)"待解密的密文";
  const unsigned char *key = (const unsigned char *)"密钥";
  const unsigned char *iv = (const unsigned char *)"初始化向量";
  unsigned char plaintext[AES_BLOCK_SIZE * ((strlen((const char *)ciphertext) + AES_BLOCK_SIZE - 1) / AES_BLOCK_SIZE)];

  memset(plaintext, 0, sizeof(plaintext));
  aes_decrypt_cbc(ciphertext, strlen((const char *)ciphertext), key, iv, plaintext);

  printf("解密结果：%s\n", plaintext);

  return 0;
}

需要注意的是，以上代码使用的是 CBC 模式和 PKCS7 填充方式。同时，需要在编译时链接 OpenSSL 库，可以使用以下命令进行编译：

gcc aes_cbc_encrypt.c -o aes_cbc_encrypt -lcrypto
gcc aes_cbc_decrypt.c -o aes_cbc_decrypt -lcrypto

其中，`-lcrypto` 参数表示链接 OpenSSL 库。