C ++ Sha1问题与使用char * [英] C++ Sha1 issue with using char *

问题描述

  #include< stdio.h> 
 #include< string.h> 
 #include< openssl / sha.h> 
 #include< string.h> 
 #include< iostream> 
 #include< stdlib.h> 
 #include< sstream> 
 
 using namespace std; 
 
 int main（）
 {
 std :: stringstream ss; 
 
 std :: string data; 
 data =hello worl; 
 unsigned char digest [SHA_DIGEST_LENGTH]; 
 char * string1 = strdup（data.c_str（））; 
 //使用string1执行操作
 free（string1）; 
 
 SHA1（（unsigned char *）& string1，strlen（string1），（unsigned char *）& digest）; 
 
 char mdString [SHA_DIGEST_LENGTH * 2 + 1]; 
 
 for（int i = 0; i  sprintf（& mdString [i * 2]，％02x，（unsigned int）digest [i] ）; 
 
 ss.str（）; 
 ss<< mdString; 
 
 cout<< ss.str（）<< std :: endl; 
 return 0; 
} 
  

我的输出总是一样的。

  ./ sha 
 da39a3ee5e6b4b0d3255bfef95601890afd80709 
  

即使我将数据的内容更改为hello panda或hello ki也给我相同的输出。

更新：
我拿走了自由

  user1 @ ubuntu：〜/ yes / coding $ g ++ -o sha sha.cpp -lcrypto 
 user1 @ubuntu：〜/是/编码$ ./sha 
 1bc8b06c5cd4e774195293ea00c959173d8d3789 
 USER1 @ Ubuntu的：〜/是/编码$ ./sha 
 c8cf70c522fc564aedb5894a24613542702172ca 
 USER1 @ Ubuntu的：〜/是/编码$ ./sha 
 83fbda098c3549ab1347d6cf708ac85092200423 
 USER1 @ Ubuntu的：〜/是/编码$ ./sha 
 ea6ccffd78236e22da412ed90a852329f59f8fd5 
 USER1 @ Ubuntu的：〜/是/编码$ ./sha 
 0413799befebcb23f5a5c970e48febc7f1aa27fb 
 USER1 @ Ubuntu的：〜/是/编码$ ./sha 
 7bd8e7952c78e282b8c117f8c537c456b66207d9 
  

即使我没有改变数据的内容，sha也会改变。

解决方案

  char * string1 = strdup（data.c_str（））; 
 //使用string1执行操作
 free（string1）; 
 
 SHA1（（unsigned char *）& string1，strlen（string1），（unsigned char *）& digest）; 
  

有您的错误。

• 您创建了string1


• 您使用了


• 您已将其释放



• 
  
  

  ---

  
  
  

  除此之外：

    SHA1（（unsigned char *）& string1 ，strlen（string1），（unsigned char *）& digest）; 
    

  你在这里做的是传递 char * string1 转换为 unsigned char * 。你想做的是传递 string1 ，而不是& string1 。这同样适用于 digest 。

  
  

  #include <stdio.h>
  #include <string.h>
  #include <openssl/sha.h>
  #include <string.h>
  #include <iostream>
  #include <stdlib.h>
  #include <sstream>
  
  using namespace std;
  
  int main()
  {
  std::stringstream ss;
  
      std::string data;
      data = "hello worl";
      unsigned char digest[SHA_DIGEST_LENGTH];
      char *string1 = strdup(data.c_str());
      // do stuff with string1
      free(string1);
  
      SHA1((unsigned char*)&string1, strlen(string1), (unsigned char*)&digest);    
  
      char mdString[SHA_DIGEST_LENGTH*2+1];
  
      for(int i = 0; i < SHA_DIGEST_LENGTH; i++)
           sprintf(&mdString[i*2], "%02x", (unsigned int)digest[i]);
  
  ss.str("");
  ss << mdString;
  
   cout << ss.str() << std::endl;
      return 0;
  }
  

  My output always the same..

  ./sha
  da39a3ee5e6b4b0d3255bfef95601890afd80709
  

  Even i change the content of data to "hello panda" or "hello ki" also give me the same output.

  Update: I took away the free

  user1@ubuntu:~/yes/coding$ g++ -o sha sha.cpp -lcrypto
  user1@ubuntu:~/yes/coding$ ./sha
  1bc8b06c5cd4e774195293ea00c959173d8d3789
  user1@ubuntu:~/yes/coding$ ./sha
  c8cf70c522fc564aedb5894a24613542702172ca
  user1@ubuntu:~/yes/coding$ ./sha
  83fbda098c3549ab1347d6cf708ac85092200423
  user1@ubuntu:~/yes/coding$ ./sha
  ea6ccffd78236e22da412ed90a852329f59f8fd5
  user1@ubuntu:~/yes/coding$ ./sha
  0413799befebcb23f5a5c970e48febc7f1aa27fb
  user1@ubuntu:~/yes/coding$ ./sha
  7bd8e7952c78e282b8c117f8c537c456b66207d9
  

  The sha change everytime, even i did not change the content of data

  解决方案

  char *string1 = strdup(data.c_str());
  // do stuff with string1
  free(string1);
  
  SHA1((unsigned char*)&string1, strlen(string1), (unsigned char*)&digest);
  

  There's your error.

  • You created string1
  • You used it
  • You freed it
  • You used it again

  Don't free what you still need to use.

  ---

  In addition to that:

  SHA1((unsigned char*)&string1, strlen(string1), (unsigned char*)&digest);
  

  What you're doing here is passing the address of char* string1 converted to an unsigned char*. What you want to do is pass string1 instead of &string1. The same applies to digest.

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