openssl的aes128_ECB加密解密运算实例

aes128算法ECB接口

加密接口

注意事项：

EVP_EncryptInit_ex初始化算法EVP_aes_128_ecb()，和密钥，key至少16B
EVP_EncryptUpdate加密运算，tmplen输出已加密长度
EVP_EncryptFinal_ex结束运算，如果在此仍有加密运算，则加密长度tmplen需补充到密文长度中

int openssl_aes128_encrypt_ecb(unsigned char *key,unsigned char *iv, unsigned char in_buf, int in_len, unsigned char out_buf,int out_len)
{
EVP_CIPHER_CTX ctx = NULL;
ctx = EVP_CIPHER_CTX_new();
int tmplen = 0;
printf("%s %d\n", func, LINE);
EVP_EncryptInit_ex(ctx, EVP_aes_128_ecb(), NULL, key, NULL);
```
  if (!EVP_EncryptUpdate(ctx, out_buf, &tmplen, in_buf, in_len))
  {
      EVP_CIPHER_CTX_free(ctx);
      return -1;
  }
  *out_len = tmplen;

  if (!EVP_EncryptFinal_ex(ctx, out_buf + *out_len, &tmplen))
  {
      EVP_CIPHER_CTX_free(ctx);
      return -2;
  }

  *out_len += tmplen;
  EVP_CIPHER_CTX_free(ctx);
  return 0 ;
```
}

解密接口

注意事项：

EVP_DecryptInit_ex初始化算法EVP_aes_128_ecb()，和密钥，key至少16B
EVP_DecryptUpdate解密运算，tmplen输出已解密长度
如果剩余字节是16B，再次使用EVP_DecryptUpdate

如果剩余字节不是16B整数倍，使用EVP_EncryptFinal_ex结束运算，输出加密长度tmplen补充到密文长度中

int openssl_aes128_decrypt_ecb(unsigned char *key,unsigned char *iv, unsigned char in_buf, int in_len, unsigned char out_buf,int out_len)
{
int ret = 0 ,tmplen = 0;
EVP_CIPHER_CTX ctx = NULL;
ctx = EVP_CIPHER_CTX_new();
EVP_CIPHER_CTX_set_padding(ctx, 0);
printf("%s %d\n", func, LINE);

  EVP_DecryptInit_ex(ctx, EVP_aes_128_ecb(), NULL, key, NULL);

  if (!EVP_DecryptUpdate(ctx, out_buf, &tmplen, in_buf, in_len))
  {
      EVP_CIPHER_CTX_free(ctx);
      return -1;
  }
  *out_len = tmplen;

  if (in_len > tmplen) {
      if (!EVP_DecryptUpdate(ctx, out_buf+tmplen, &tmplen, in_buf+tmplen, in_len-tmplen))
      {
      //        RSP_TRACE("%s EVP_DecryptUpdate error \n", __func__);
          EVP_CIPHER_CTX_free(ctx);
          return -1;
      }
      *out_len += tmplen;
  }

  if (in_len %16!=0){
      ret = EVP_DecryptFinal_ex(ctx, out_buf+tmplen, &tmplen);
      fprintf(stderr, "err:\n");
      if (ret != 0)
      {
      //        RSP_TRACE("%s EVP_DecryptFinal_ex error ret=%d\n", __func__, ret);
          EVP_CIPHER_CTX_free(ctx);
          return -2;
      }
      *out_len += tmplen;
  }

  EVP_CIPHER_CTX_free(ctx);
  return 0 ;

}