3DES解密后在C中将char解码为UTF8

Question

我需要一些帮助将 C 中的字符解码为其 UTF8 解释。

到目前为止我的代码是这样工作的：

A char 初始化为 'password' 70617373776F7264
然后使用3DES加密DD201F609E49C0609FABA4C8AAFBB1E5
然后使用3DES解密成功70617373776F72640808080808080808

在printf("decrypted: %s",dec)语句中，一切正常，显示为decrypted: password

但是当进行字符串比较时，它不匹配。仔细观察 char，我可以看到它显示为 [=17=]1password00000000（这是由于填充）

有什么方法可以取消填充或解码为 UTF8？ something similar to this

使用代码编辑：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <openssl/des.h>
#include <openssl/rand.h>
#include <ldap.h>
#include "k.h"
#include "hex.h"


#define ULONG unsigned long
#define INT unsigned int


char *encrypt(char *data)
{

  int i = 0;
  int len = 0;
  int nlen = 0;


  char *key1 = "1313232323231313";
  char *key2 = "6789678967896789";
  char *key3 = "1313232323231313";

  /* Padding */
  char ch = '[=10=]';
  unsigned char out[64] = {0};
  unsigned char src[64] = {0};


  unsigned char *ptr  = NULL;
  unsigned char block[8] = {0};
  DES_key_schedule ks1, ks2, ks3;

  /* set password table */
  ptr = hex2bin(key1, strlen(key1), &nlen);
  memcpy(block, ptr, sizeof(block));
  free(ptr);
  DES_set_key_unchecked((C_Block *)block, &ks1);

  ptr = hex2bin(key2, strlen(key2), &nlen);
  memcpy(block, ptr, sizeof(block));
  free(ptr);
  DES_set_key_unchecked((C_Block *)block, &ks2);

  ptr = hex2bin(key3, strlen(key3), &nlen);
  memcpy(block, ptr, sizeof(block));
  free(ptr);
  DES_set_key_unchecked((C_Block *)block, &ks3);

  ptr = hex2bin(data, strlen(data), &nlen);
  memcpy(src, ptr, nlen);
  free(ptr);

  len = (nlen / 8 + (nlen % 8 ? 1: 0)) * 8;

  ch = 8 - nlen % 8;
  memset(src + nlen, ch, (8 - nlen % 8) % 8);

  printf("Raw data: ");
  for (i = 0; i < len; i++) {
      printf("%02X", *(src + i));
  }
  printf("\n");

  for (i = 0; i < len; i += 8) {
      DES_ecb3_encrypt((C_Block *)(src + i), (C_Block *)(out + i), &ks1, &ks2, &ks3, DES_ENCRYPT);
  }

  printf("Encrypted: ");
  for (i = 0; i < len; i++) {
      printf("%02X" , *(out + i));
  }
  printf("\n");


  return out;

}


char *decrypt(char *data)
{

  int i = 0;
  int len = 0;
  int nlen = 0;


  char *key1 = "1313232323231313";
  char *key2 = "6789678967896789";
  char *key3 = "1313232323231313";

  /* Padding */
  int ch = 0;
  unsigned char out[64] = {0};
  unsigned char src[64] = {0};


  unsigned char *ptr  = NULL;
  unsigned char block[8] = {0};
  DES_key_schedule ks1, ks2, ks3;

  /* set password table */
  ptr = hex2bin(key1, strlen(key1), &nlen);
  memcpy(block, ptr, sizeof(block));
  free(ptr);
  DES_set_key_unchecked((C_Block *)block, &ks1);

  ptr = hex2bin(key2, strlen(key2), &nlen);
  memcpy(block, ptr, sizeof(block));
  free(ptr);
  DES_set_key_unchecked((C_Block *)block, &ks2);

  ptr = hex2bin(key3, strlen(key3), &nlen);
  memcpy(block, ptr, sizeof(block));
  free(ptr);
  DES_set_key_unchecked((C_Block *)block, &ks3);

  ptr = hex2bin(data, strlen(data), &nlen);
  memcpy(src, ptr, nlen);
  free(ptr);

  len = (nlen / 8 + (nlen % 8 ? 1: 0)) * 8;

  ch = 8 - nlen % 8;
  memset(src + nlen, ch, (8 - nlen % 8) % 8);

  printf("Raw data: ");
  for (i = 0; i < len; i++) {
      printf("%02X", *(src + i));
  }
  printf("\n");

  for (i = 0; i < len; i += 8) {
      DES_ecb3_encrypt((C_Block *)(src + i), (C_Block *)(out + i), &ks1, &ks2, &ks3, DES_DECRYPT);
  }

  printf("Decrypted: ");
  for (i = 0; i < len; i++) {
      printf("%02X", *(out + i));
  }

  printf("\n");
  return out;

}


K DES_ecb3_do(K user, K pass,K fl )
{
  int res = 0;
  int flag = fl->i;
  char *usn = user->s;

  char *enc = pass->s;
  char *decr = "";
  char dec[32];

  if(flag==1)
  {
    decr = encrypt(enc);
    strcat(dec,decr);
  }
  else if(flag==0)
  {
    decr = decrypt(enc);
    strcat(dec,decr);
  }
  int ret;
  ret = strcmp(dec, "password");
  if(ret==0)
  {
    printf("they match");
  }
  else
  {
    printf("they don't match\n");
    return (K) 0;
  }  
 printf("decrypted pass is:%s\n",dec);

   return ks(dec);
}

Answer 1

是不是因为你解密后的字符串没有以NULL结尾？另外，如果您的 "string comparison" 是如果（dec == "password"）那是行不通的，试试如果 (strcmp(dec, "password") == 0)

Answer 2

在 decrypt 函数中，您 return 从局部变量解密的结果，该变量超出了调用者的范围。

将 out[64] 更改为 static 或作为全局，或 malloc 它。

最后您的代码调用 UB 因为您正在 return 获取堆栈区域的地址。

OP 评论请求后编辑

您的密码是

char *decrypt(char *data)
{

  int i = 0;
  int len = 0;
  int nlen = 0;


  char *key1 = "1313232323231313";
  char *key2 = "6789678967896789";
  char *key3 = "1313232323231313";

  /* Padding */
  int ch = 0;
  unsigned char out[64] = {0};
  unsigned char src[64] = {0};

  // stuff....
 return out;
}

此代码将输出数组声明为本地数组，否则已分配堆栈。该变量仅在局部范围内可用：在 decrypt 函数内。

这意味着当函数return调用函数DES_ecb3_do时一个内存地址可能被破坏。您不应访问该地址。

要解决此问题，您必须使 out 变量在 decrypt 函数范围之外可用，例如，使用以下方法之一：

1) 您将 out 定义为 global:

unsigned char out[64] = {0};

char *decrypt(char *data)
{
   // STUFF
}

2) 在函数中将 out 定义为 static：

char *decrypt(char *data)
{
   static unsigned char out[64] = {0};
   // STUFF
}

3) 您将 out 定义为指针，并且 malloc 它：

char *decrypt(char *data)
{
   unsigned char *out] = malloc(64);
   // STUFF
}

希望已经足够清楚了。

3DES解密后在C中将char解码为UTF8

Decoding char to UTF8 in C after 3DES decryption

c

encryption

3des

padding