Solved

Create salted MD5 passwort for /etc/shadow

Posted on 2012-12-30

1 solution

Medium Priority

625 Views

Last Modified: 2012-12-30

Hi

I am trying to generate a salted md5 hash in C with the propper format "$1$salt$hash" for the /etc/shadow file.

I am not quite sure if $1$ should be part of the salt or not? Right now I use the following code to generate a salt and create the passwort using crypt()

char salt[9];
  char full[50];

  int i = 0;
  static char *choices = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
                         "0123456789./";

  for(i = 0; i<8; i++)
  {
    salt[i] = choices[random_in_range(0, strlen(choices) - 1)];
  }
  salt[8] = 0;

  sprintf(full,"$1$%s",salt);

  /* Loop thru passwd file */
  char pw[100];

  sprintf(pw,"$1$%s$%s",salt,crypt(password, full));

Open in new window

Any hint would be great!

Comment

Question by:Chris Sandrini

[X]

Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

Help others & share knowledge
Earn cash & points
Learn & ask questions

Join The Community

1 Comment

LVL 11

Accepted Solution

by:Chris Sandrini

Chris Sandrini earned 0 total points

ID: 387313762012-12-30

Nevermind. I found a solution to even create SHA-512 passwords. This is my code

int setPassword(const char *password)
{
  FILE* fps;

  struct spwd *sp;
  memset(&sp, 0, sizeof(sp));

  if (!(fps = fopen("/etc/shadow", "r+"))) {
    return 0;
  }

  char user[20] = "amber";
  char salt[9];
  char full[50];

  int i = 0;
  static char *choices = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
                         "0123456789./";

  for(i = 0; i<8; i++)
  {
    salt[i] = choices[random_in_range(0, strlen(choices) - 1)];
  }
  salt[8] = 0;

  sprintf(full,"$6$%s",salt);

  /* Loop thru passwd file */
  char pw[100];

  sprintf(pw,"%s",crypt(password, full));



  while ((sp = getspent()) != NULL) {
    if (strcmp(sp->sp_namp,user) == 0 ) {
      strcpy(sp->sp_pwdp,pw);
      putspent(sp, fps);
    } else {
      putspent(sp,fps);
    }
  }

  fclose(fps);

  return 1;
}

Open in new window

Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Simple Binding. Cocoa GUI Application without Outlets.

Article by: pgnatyuk

An Outlet in Cocoa is a persistent reference to a GUI control; it connects a property (a variable) to a control. For example, it is common to create an Outlet for the text field GUI control and change the text that appears in this field via that Ou…

The Most Dominant 2016 Cyber Attack Vectors

Article by: Adam

Examines three attack vectors, specifically, the different types of malware used in malicious attacks, web application attacks, and finally, network based attacks. Concludes by examining the means of securing and protecting critical systems and inf…