/* compile with -lcrypt */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define _XOPEN_SOURCE
#include <unistd.h>

char *crypt(const char *key, const char *salt);

#define SECRETFILE "/home/tentti/.salaisuus"
char salt[] = "kR";

int main(void)
{
  char password[32];
  char encryptedpw[] = "kRgzA/gPPPf0Q";
  char secret[30];
  char *hash;
  int authenticated = 0;
  FILE *f;

  printf("Password: ");
  scanf("%s", password);

  hash = crypt(password, salt);

  authenticated |= !(strcmp(hash, encryptedpw));

  if (authenticated) {
    if (!(f=fopen(SECRETFILE,"r"))) {
      perror("fopen()");
      exit(1);
    }
    fgets(secret, sizeof(secret), f);
    fclose(f);
    printf("secret is '%s'\n", secret);
  } else {
    printf("wrong password, sorry\n");
  }
  exit(0);
}