good_enough_password.c

/* You can successfully authenticate to this program by entering the password
 * as seen in the code below, or by doing something else.  What is it and why?
 *
 * $ make good_enough_password
 * $ ./good_enough_password
 * Enter password:
 *
 * Hint: The problem is worse on a 32bit platform.  To compile for 32bit on OSX
 * $ cc -m32 -o good_enough_password good_enough_password.c
 * $ ./good_enough_password
 * Enter password:
 *
 */

#include <stdio.h>
#include <string.h>
#include <stdbool.h>

#define MAXLEN 255

int main(int argc, const char *argv[])
{
  char *password = "secret squirrel";
  char guess[MAXLEN];
  bool authenticated = false;

  while (!authenticated) {
    printf("Enter password: ");
    fgets(guess, MAXLEN, stdin);

    if (!strncmp(password, guess, sizeof password)) {
      authenticated = true;
      printf("Success!  You are now authenticated!\n");
    }
  }

  printf("You entered     : \"%s\"\n", guess);
  printf("The password was: \"%s\"\n", password);

  return 0;
}