Putting a password on the prog

Hey all, How would go about putting a 2-digit password or w/e into the code so the person who is running the program would have to know the password to gain access to the info the program holds? Also would I make case for when somebuddy types in the password or the wrong password. For example it would say "Correct password Welcome" or "wrong password please try again."

Just basic stuff.

Code:

---

#include <iostream>
#include <string>

int main ( void )
{
       
        std::string Password;
       
        std::cin >> Password;
       
        if ( Password == "Pw" ) std::cout << "Correct";
        else std::cout << "Error";
       
        return 0;
       
}

---

[edit]
Fixed code..

Code:

---

#include <iostream>
#include <cstring>

int main(char argc, char **argv)
{
    if (argc < 2)
    {
        std::cout << "The correct usage is <programname> <password>";
        return(-1);
    }

    if (strcmp(**argv, "Your_Password_Here") != 0)
    {
        std::cout << "Invalid password.";
        return(-2);
    }

    // Your program code.

    return(0);
}

---

I believe this will work. Not sure on the strcmp() though.

close lithorien. you are actually dereferencing the double pointer back to its char value though.

Code:

---

#include <iostream>
#include <cstring>

int main(char argc, char **argv)
{
    if (argc < 2)
    {
        std::cout << "The correct usage is <programname> <password>";
        return(-1);
    }

    if (strcmp(argv[1], "pass") != 0)
    {
        std::cout << "Invalid password.";
        return(-2);
    }
        else
        {
                std::cout << "Password is OK";
        }

    // Your program code.

    return(0);
}

---

Eee-whoops. I knew something didn't look right about it. Thanks! :)

Inferno,

I think I should explain the differences in the two examples here.

My example is asking the user for the password after he has executed the program.
bithub/lithoriens example is done from the command line

e.g.

Code:

---

C:\Prog.exe Pw

---

Pw being the password

Either one works, its up to you to choose.

You have 10secs before this post self-destructs.

>if ( Password == "Pw" )
Of course, the next problem is how to stop the inquisitive types with a hex editor from simply opening up your executable and seeing the password as clear as day.

thank you very much everyone

Quote:

---

Originally Posted by Salem

>if ( Password == "Pw" )
Of course, the next problem is how to stop the inquisitive types with a hex editor from simply opening up your executable and seeing the password as clear as day.

---

Maybe you could ask for the pw and then convert the user input to binary.

>if ( Password == *some binary number* )

He'd have to convert it to ascii first

You can make it hard to find the password in your exe, but you can't make it impossible.

What you could do is encrypt part of the program code so that the password is required for correct decrypting.

Write your password string characters inverted to a file, open the file and copy the inverted string back to your source file.

Suppose you want "ab" as password, do this in another program:

Code:

---

FILE *fp = fopen("c:\\test.txt", "w");
if (fp)
{
  fprintf(fp, "%c%c", (char)~'a', (char)~'b');
  fclose(fp);
}

---

This program will write "ž�" to file and then you can copy that to your source file. This way it gets a little harder to decipher the binary.

so if i were to use salems example it be like this

Code:

---

#include <iostream>
#include <stdlib.h>

using namespace std;

int main(int argc, char *argv[])
{
    char Password[100]
   
    cout << " blah blah 2 digit password\n";
    cin >>name<<\n;
    if ( Password == "69" )
    cout >> "blah\n";

  system("PAUSE");       
  return 0;
}

---

One interesting method for the password I just thought of would be to have the password set up so that the first half when processed a certain way was equal to the second half.

Like the password might be "ažb�". Then it would reverse the odd characters and if they were equal to the even characters then the password would be correct.

The good part is the password would not be stored internally and should be more difficult to break. The bad part is, unless coded to have something specific for each person, that any correct password would pass.

how exatctly would i go about encrypting the code would i seperate into two files and then use a file encrypter to lock just one ?????

It really doesn't matter how complicated you make it
At some point, cracking the password becomes too hard

Code:

---

if ( something_complicated(user,secret) == 0 ) {
  // the good stuff
}

---

Your attacker simply changes the code to be

Code:

---

if ( something_complicated(user,secret) != 0 ) {
  // the good stuff
}

---

Which is usually a simple matter of editing one instruction in the machine code.

So instead of getting the password right, you just have to get the password wrong

ok Thanks Salem.... Also I have one more question about the Password for any of you.

Code:

---

#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
  char Password[100]
  cout<<"Please enter the 3 digit password";
  cin>>Password;
  if ( Password == 123 )
  cout<<"You've enter the correct password Congratulation!";
 
  system("PAUSE");       
  return 0;
}

---

There is nothing saying nething about a password in this which causes the the code when compiled to give an error. So anyway what I was wondering is what am I supposed to put the PW "123" as i tried putting it as int 123 up near the char but that didnt work(I only assumed i should do this becuase i thought it might need somewhere to start to actually run in the program)

>> if ( Password == 123 )

c'mon now, you know you can't compare a char array like that! use strcmp() with char array (not int!) parameters. std::strings do have an overloaded operator == though, so you can use one like this:

>> if ( Password == "123" )

@Inferno & Sebastiani :

haha, it's running ok after make a little correction!

Code:

---

#include <iostream>
#include <cstring>  //add this for use string type

using namespace std;

int main(int argc, char *argv[])
{
  char Password[100];          //add ';'

  cout<<"Please enter the 3 digit password: ";
  cin>>Password;
 
  if ((string) Password == "123" )  //converter array to string type
  cout<<"\nYou've enter the correct password Congratulation!";
 
  cout<<endl<<endl;
  system("PAUSE"); 
  return 0;
}

---

Try this... much better than your attempt to cast to a string type (the proper string header is <string>).

Code:

---

#include <iostream>
#include <string>  //add this for use string type

using namespace std;

int main(int argc, char *argv[])
{
  string Password;

  cout<<"Please enter the 3 digit password: ";
  cin>>Password;
 
  if (Password == "123")
    cout<<"\nYou've enter the correct password Congratulations!";
 
  cout<<endl<<endl;
  system("PAUSE"); 
  return 0;
}

---

@ jlou :

Thanks for your help, I always think <cstring> is right head for string,
now I know <string> is alright.

Thanks very much all of you for your help :D

Try to use my optimize version.
It is likely C version, but anyway more optimize about space and memory.

Regards. :)

Now I've fixed event when input data buffer longer than expected.

Thanks.
Regards. :D

Code:

---

#include <iostream>

using namespace std;
char def_pass[]="iloveyou";

int main()
{
                static int i =        strlen(def_pass)+1;
                char* pPassword = new char[i];
                cout << "Please enter the password:\n";
                //cin  >> pPassword; // ok, maybe error
                fgets (&pPassword[0], i, stdin) ;  // replacement               
if (strcmp(pPassword,def_pass)!=0)
                        {
                        cerr << "Incorrect password.";
                        return 1;// exit program with error code = 1
                        }       
                cout << "Correct password.";
                delete pPassword;
                //
                //program begin here!

                //
                return 0;
}

---

This may crash if the password entered is longer than the real one.

thanks, CornedBee

I've fixed.

You see?

It is OK, now?

Well, it's one way to do it.