Saving my Password in a file

Hi.
I am trying to safe a password but I fail because he don't seems to read it, I can't figure it out. Here is some code:

Code:

---

First of I gave it some kind of 'default' setting:

#include <fstream>
#include <iostream>
#include <math.h>
#include <windows.h>

using namespace std;

//here is some other code, not necessary now

char ThePassword[] = "password";

int main()
{
    ifstream A ( "Startup.txt" );
    A.close();
//here is some other code, not necessary now
}

then later in the code you can change the password in a option ( if
 you want to change the password )

//here is some other code, not necessary now

    ofstream B ( "Startup.txt" );
    B<< ThePassword<<endl;
    B.close();

//here is some other code, not necessary now

but the problem is he doesn't seem to read the file he wrote, first
 he get's the 'default' password then he read's the file, so if there
 isn't a file, he wont read it, then you can give it an other password
 he save's that then if you close program and open up again he
 read's 'default' password but then he read's the file that now Does
exist so the ThePassword should get a other value but he doesn't
read the file and I don't know why, please help me.
( if there's isn't enough code plz tell me, i can add some more, thank you )

---

Well unless you post the code which tries to read and compare the password, it could be anything.

Here is my source, hopes that it would help you:

I'm not rummaging in 17K of source code just for that.
Practice with a small test program to help you figure out the answer, and if you're still stuck post your test code, not your main code.

Quote:

---

Originally Posted by Salem

I'm not rummaging in 17K of source code just for that.
Practice with a small test program to help you figure out the answer, and if you're still stuck post your test code, not your main code.

---

I agree. Jeez the source has no indentation what-so-ever (I was going to try and help...).

:p

The only problem is, is that if you changed your password he write's a file with the new password so if you return to the begin and he ask for your password and enter the new password it works but doesn't make any sence, if you change your password and he wrote on a file and then quit the program (shut it down) and open it for the next time (so you should have a new password) he read's the file (just like I said in the first post) and should use the new password but he doesn't, that's my problem if you insert a string like "test" for a new password he write's it into the file as just: test he can read that if you don't quit the program but it seems he doesn't read it if you quit the program and start the program again as a "save the new password for next time I use this program". Maybe there is something wrong with the write file function:

ofstream B ( "Startup.txt" );
B<< ThePassword<<endl; //ThePassword is a string for... the password
B.close();

or with my read file function:

ifstream A ( "Startup.txt" );
A.close();

(I don't get compile error's!)
I can't figure it out why he can't read it as a new password, maybe one of you know, thx anyway.

>> or with my read file function: <<

Yes, indeed. The problem, of course, would be that you open the file, and then close it. Something should happen between those two events, namely, reading the password stored in the file. If you are using std::string, then have a look here: http://cppreference.com/cppstring/getline.html
and, for c-style strings: http://cppreference.com/cppio/getline.html

Sorry but I really don't get it :( ( I am a beginner at C++ ) and the site too.

Try reading the "C++ Text File Input & Output" tutorial on my tutorial page for some instruction on how to properly read/write text files in C++. See my sig for the link.

Good luck to ya.

how does a beginner not fimilar with anything,
come up witha 17k source file.

I think I started wrong, some (easy) things I already should know I don't know and the other way around. I still can upload it if you want but it isn't a big (I don't mean it in size) thing. Oh yeah I would like to thank LuckY (for the tutorial), this was my fix (if you would like to know):

Code:

---

    A.getline(ThePassword, 100).good();

---

Basically, your problem is this (from what I've seen so far):

Code:

---

ifstream A ( "Startup.txt" ); // Opening the file...
? // Something missing here... namely, reading data...
A.close(); // Closing the file...

---

Take a look at the links I posted. Using getline is a very good method of reading in strings (particularly c-style strings where you have to worry about buffer length).

*edit*
Alright, I see you've figured it out. The only reason you'd call good( ) is to check the status, but it needs to be the conditional of an if statement.

Cheers

Ok thx, still I find it hard to read the links you gave (yes I am a noob)). But I got another problem:

Code:

---

If I write this:

    ofstream C ( "Startup.txt" );
    C<< ThePassword<<endl;
    C<< TheConfirmCode<<endl;
    C.close();

and read it like this:

    ifstream A ( "Startup.txt" );
   
    if ( A.is_open() ){
    A.getline(ThePassword, 100);
    A.close();
    }

and:

    ifstream B ( "Startup.txt" );
   
    if ( B.is_open() ){
    B.getline(TheConfirmCode, 100);
    B.close();
    }

he will read the same as ThePassword because he just read the
first line, how can I get it like he will read the line under the first line
or that he Doesn't read the first 5 characters and start reading after
the first 5 and stop reading after the Size of the ThePassword, that
would really help, thank you.

---

Don't open a second file (B), just call getline a second time with A before you close it.

Hmm it doesn't seem to help if I do this it doesn't work:

Code:

---

If I write this:

    ofstream B ( "Startup.txt" );
    B<< ThePassword<<endl;
    B<< TheConfirmCode<<endl;
    B.close();

and read it like this:

    ifstream A ( "Startup.txt" );
   
    if ( A.is_open() ){
    A.getline(ThePassword, 100);
    }

and:

    ifstream A ( "Startup.txt" );
   
    if ( A.is_open() ){
    A.getline(TheConfirmCode, 100);
    A.close();
    }

Note:

    ifstream A ( "Startup.txt" );
   
    if ( A.is_open() ){
    A.getline(ThePassword, 100);
    }

Is located in int Password()
and:

    ifstream A ( "Startup.txt" );
   
    if ( A.is_open() ){
    A.getline(TheConfirmCode, 100);
    A.close();
    }

is located in int ConfirmCode()

Maybe that is why it doesn't work but I don't know, and still I can't
figure it out how to read After a few characters in a file with
getline() or something.

---

Declare the ifstream outside of either Password() or ConfirmCode() and pass it to both functions as a parameter by reference. That way the stream will remain open and the pointer that reads the file will remain in place between function calls.

Code:

---

ifstream fin("sample.txt");
if(!fin)
  cerr << "unable to open file" << endl;

int x;
x = Password(fin);
if(x == 1)
  ConfirmCode(fin);

---

where Password() and ConfirmCode() are declared with a reference to an ifstream object as a parameter like this:

int Password(ifstream &);

When you're done pass fin around, you can close it.

I got it now in int main() like this:

Code:

---

int main()
{
    ifstream A ( "Startup.txt" );
   
    if ( A.is_open() ){
    A.getline(ThePassword, 100);
    A.getline(TheConfirmCode, 100);
    A.close();
    }
   
    Password();
}

---

This work 50 % it reads the ThePassword and the TheConfirmCode well but I can't put other letters and numbers in front of it :(. I didn't use (or understand) your method because I don't know pointers and references, I'm still learning. But it would usefull for me if I know how he starts reading after a number of characters and stop reading after the size of the ThePassword and the TheConfirmCode I allready tried much but I think I need to use something with strlen, thx anyway.

or keep it basic with:

Code:

---

    char ThePassword[256];
    cout << "The Current Password Is: ";
    ifstream B ("Startup.txt");
    cout << ThePassword << endl;
    B.close();
    char PasswordChange[2];                   
    cout << "Would you like to change your password? Y/N: ";
    cin.getline ( PasswordChange, 2, '\n' ); 
    if ( strcmp ( PasswordChange, "Y" ) == 0 ) {
      cout << "Enter New Password: ";
      cin.getline ( ThePassword, 256, '\n' );
      ofstream NewPass ("Startup.txt");
      NewPass << ThePassword;
      NewPass.close();
      ifstream SeePass ("Startup.txt");
      SeePass.close();
      cout << "Your Password Has Been Changed To: " << ThePassword << endl;
      cin.get();
      }
    else {
    cout << "Your Password Is The Same!" << endl;
    cin.get();

---

There may be flaws, i know it doesnt save the new password (After you reatart the program, it says your password is password), but you can figure that out, this is a 5 minute code written to help you, i dont give all the answers out you know...

Code:

---


int Password(char * p)  //confirms user password with password read from file
{
  cout << "please enter your password" << endl;
  char pw[101];
  cin >> pw;
  if password entered same as password read in
    return 1;
  else
    return 0;
}

int ConfirmCode(char * c)  //confirms confirmation code same as read from file
{
  cout << "enter confirmation code" << endl;
  char  cc[101];
  cin >> cc;
  if confirmation code entered is same as confirmation code read in
    return 1;
  else
    return 0;
}

int main()
{
    char ThePassword[101];
    char TheConfirmCode[101];
    ifstream A ( "Startup.txt" ); //open A to read data from file Startup.txt
   
    if ( A.is_open() ){  //if Startup.txt open for reading
    A.getline(ThePassword, 100);  //read into a variable called ThePassword
    A.getline(TheConfirmCode, 100); //read into a variable called TheConfirmCode
    A.close();  //close A
    }
 
  int x;
  x =  Password(ThePassWord);  //call Password.
  if(x == 1)
      x = ConfirmCode(TheConfirmCode); //call ConfirmCode
      if(x == 1)
        //run rest of program
      else
        cout << "incorrect confirmation code entered" << endl;
  else
    cout << "incorrect password entered" << endl;
 
}

---

>> But it would usefull for me if I know how he starts reading after a number of characters and stop reading after the size of the ThePassword and the TheConfirmCode I allready tried much but I think I need to use something with strlen, thx anyway.

Why do you need to know that? It looks like your password and confirmation were each written on separate lines (the endl adds a new line when you write them out). When you read them in you just read in a whole line, it doesn't matter how long the password is.

It's just to easy to read the ThePassword from the Startup.txt so I thought to add some characters in to the file so that you wont really notice just the ThePassword and the TheConfirmCode, but with only getline() it wont really works, I need to skip characters that he wont read all characters on that line.

I see. If you want to add extra characters then there are several ways you could do it. It is a basic form of encryption. You could write out the number of characters in the password to the file, so that you know how many characters in the line belong to the password and how many are extra garbledness you added. You write out/read in the integer first, then the rest of the line is the password and extra characters. You could also intersperse the extra characters into the password, as long as you remember where you did that. For example, you could insert an extra character between every password letter when you write out the password, and when you read it in, you remove every other letter.

As long as the method you use to write it out follows the same format as how you read it in, you will be fine, you just have to make sure that you write all the information you need to the file.

Yeah that's was my idee but I don't have any idee how to do that, I tried somethings but till now on nothing worked.

One of the simplest forms of encryption is 'xor'.

It is simple to implement and reasonably secure. If you are using it for use on your home computer it is probably your best option.

Here is a snippet courtesy of major_small.

Code:

---

/*******************************************************************************
    XOR.cpp
   
    This function takes in two strings (value,key) and uses XOR encryption to
    encrypt (and decrypt) the value using the key.  it returns the encrypted
    value as a C++ string.
   
    John Shao
 
For more on XOR encryption: http://www.cprogramming.com/tutorial/xor.html
********************************************************************************
    This work is hereby released into the Public Domain. To view a copy of the
    public domain dedication, visit
    http://creativecommons.org/licenses/publicdomain/

    or send a letter to

    Creative Commons
    559 Nathan Abbott Way
    Stanford, California 94305
    USA.
*******************************************************************************/

#include <iostream>
using std::string;

string XOR(string value,string key)
{
    string retval(value);

    short unsigned int klen=key.length();
    short unsigned int vlen=value.length();
    short unsigned int k=0;
    short unsigned int v=0;
   
    for(v;v<vlen;v++)
    {
        retval[v]=value[v]^key[k];
        k=(++k<klen?k:0);
    }
   
    return retval;
}

/******************************************************************************/
/*                        Here's a Test Program                              */
/******************************************************************************/

#include<iostream>

int main()
{
    std::string value("what is your name");
    std::string key("bonebreaker");
   
    std::cout<<"Plain text: "<<value<<"\n\n";
    value=XOR(value,key);
    std::cout<<"Cipher text: "<<value<<"\n\n";
    value=XOR(value,key);
    std::cout<<"Decrypted text: "<<value<<std::endl;
   
    std::cin.get();
    return 0;
}

---

Of course, should you require more information on encryption you can always google for it.

:confused:

First, you should have a working program without the "encryption". If it doesn't work by simply writing out the password and reading it in, then fix that first. Then, add the shell of a function called Encrypt that takes a string and returns a string. Start out with it just returning the string exactly as is. Make a similar function called Decrypt that does the same thing. Once those functions compile, add code to the part of your program that writes out the password. This code should get the new password and confirmation from the user the same way, but before it writes them out to the file it should modify them by calling encrypt, for example:

Code:

---

ThePassword = Encrypt(ThePassword);
TheConfirmCode = Encrypt(TheConfirmCode);

---

In the beginning, that call won't actually change anything, but once you implement the Encrypt function it will.

Do the same for the code that reads in the password and confirm code from the file, excet call Decrypt on them after you read them in. Again, the Decrypt function won't do anything yet, but you want to set it up so that it will.

Once you have all that compiling and running, you can start on the encryption and decryption. Start with something simple. For example, to "encrypt" the password, you add a question mark to the end. To "decrypt" the password, you remove the last character (which should be a question mark). Each time you add something, make sure it works, and next thing you know, you'll have password encryption working in your program.

Ok thx, I didn't know of XOR, I gonna try some now.

You posted just after me, so be sure to read my post just above yours. You could/should use the XOR encryption once you get to the last part.

Ok thx again but when I encrypt it with XOR, (Q: ) Isn't that enough, I mean should I add the characters or is only encrypthing enough?

It depends on what you mean by enough. Virtually any encryption can be broken given the time and resources. Which type of encryption you use depends on how safe you want the data to be. You don't need to mix the XOR encryption with your simple character adding version. You could if you wanted to, but it would probably not be necessary.

Assuming you are just doing this project for fun, and you don't work for the CIA or NASA or something, I would try doing your own simple encryptions first for practice, then switch to the XOR version to see if you can get that to work.

I think the program treenef posted is usefull because (the value of) key needs to be the (at least) as long as ThePassword (to encrypt) and ThePassword is a string that you can give a value (value = value not value = value) and that value can be different in size, so ThePassword (you gave a value (because you want to change the password)) can be different in size so you can use something to measure the size of the entered string ThePassword and give key the same size with some random characters. Ok, now I don't know how or what, I can't really understand treenef's post but I thought he is doing what I explained (measure the entered string, give key the same or longer value and encrypt it with that) now I like to use char ThePassword; as a string not string; if someone can give me an explaination of treenef's post or tell me how to do that it would be great, thx.

***EDIT***
I think I found a way: use something like strlen to know how long the string ThePassword, make a loop as for and use in for something like strcal to add string and let it stop when the int (i or x, whatever) is equel to the strlen. Still need to test this so I could be wrong.