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C++ - Problem in asking and checking user's passwd

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# 1  
Old 08-08-2010
Tools C++ - Problem in asking and checking user's passwd

This is the source code:
#include <pwd.h>
#include <iostream>
#include <string.h>
using namespace std;
int main()
    struct passwd *user;
    char login[200]="alex", password[200]="qwertyuiop";

       if ((user= getpwnam(login)) == NULL)
            cout << "No such user\n";
       else if (!strcmp(user->pw_passwd, crypt(password, user->pw_passwd)))
            cout << "Password correct\n";
            cout << "Password incorrect\n";
    return 0;

but I got error about crypt..Why is that?
# 2  
Old 08-08-2010

What error are you getting? I can compile the code no problem.

I'm not sure that you can do what you are trying to do.

From the crypt man page:

The crypt() function performs password encryption, based on the NBS Data Encryption Standard (DES).
Additional code has been added to deter key search attempts

user->pw_passwd is completely obfuscated and can't be compared to a crypted version of the string password.
# 3  
Old 08-08-2010
2 errors:
1./home/alex/Qt/libtest/main.cpp:12: undefined reference to `crypt'
2.:-1: error: collect2: ld returned 1 exit status

# 4  
Old 08-08-2010
Try including unistd.h or crypt.h

If you look at the man page for crypt, it should tell you where it is.
# 5  
Old 08-08-2010
Hmmm, the undefined reference to `crypt' is just a notice, the real error is that
:-1: error: collect2: ld returned 1 exit status
# 6  
Old 08-08-2010
Originally Posted by hakermania
Hmmm, the undefined reference to `crypt' is just a notice, the real error is that
:-1: error: collect2: ld returned 1 exit status
I would say that the first line is the real error (the linker can't link something that doesn't exist).
# 7  
Old 08-08-2010
So, what do you suggest me for this?

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