Como hacer esto?

[den_22]

Hola, tengo una pregunta, como hago lo siguiente: Quiero que en vez de generarse un random password, se genere un password md5 pero que provenga de la contraseña que ingrese el usuario.
Deberia agregar el campo password en el registro, pero como cambiaria en este codigo lo que quiero hacer.

Código:

<?php

define('INCLUDE_CHECK',true);

require 'connect.php';
require 'functions.php';
// Those two files can be included only if INCLUDE_CHECK is defined

session_start();

session_name('tzLogin');
// Starting the session

session_set_cookie_params(2*7*24*60*60);
// Making the cookie live for 2 weeks


if($_SESSION['id'] && !isset($_COOKIE['tzRemember']) && !$_SESSION['rememberMe'])
{
    // If you are logged in, but you don't have the tzRemember cookie (browser restart)
    // and you have not checked the rememberMe checkbox:

    $_SESSION = array();
    session_destroy();
    
    // Destroy the session
}


if(isset($_GET['logoff']))
{
    $_SESSION = array();
    session_destroy();
    
    header("Location: index.php");
    exit;
}

if($_POST['submit']=='Login')
{
    // Checking whether the Login form has been submitted
    
    $err = array();
    // Will hold our errors
    
    
    if(!$_POST['username'] || !$_POST['password'])
        $err[] = 'All the fields must be filled in!';
    
    if(!count($err))
    {
        $_POST['username'] = mysql_real_escape_string($_POST['username']);
        $_POST['password'] = mysql_real_escape_string($_POST['password']);
        $_POST['rememberMe'] = (int)$_POST['rememberMe'];
        
        // Escaping all input data

        $row = mysql_fetch_assoc(mysql_query("SELECT id,usr FROM tz_members WHERE usr='{$_POST['username']}' AND pass='".md5($_POST['password'])."'"));

        if($row['usr'])
        {
            // If everything is OK login
            
            $_SESSION['usr']=$row['usr'];
            $_SESSION['id'] = $row['id'];
            $_SESSION['rememberMe'] = $_POST['rememberMe'];
            
            // Store some data in the session
            
            setcookie('tzRemember',$_POST['rememberMe']);
        }
        else $err[]='Wrong username and/or password!';
    }
    
    if($err)
    $_SESSION['msg']['login-err'] = implode('<br />',$err);
    // Save the error messages in the session

    header("Location: index.php");
    exit;
}
else if($_POST['submit']=='Register')
{
    // If the Register form has been submitted
    
    $err = array();
    
    if(strlen($_POST['username'])<4 || strlen($_POST['username'])>32)
    {
        $err[]='Your username must be between 3 and 32 characters!';
    }
    
    if(preg_match('/[^a-z0-9\-\_\.]+/i',$_POST['username']))
    {
        $err[]='Your username contains invalid characters!';
    }
    
    if(!checkEmail($_POST['email']))
    {
        $err[]='Your email is not valid!';
    }
    
    if(!count($err))
    {
        // If there are no errors
        
        $pass = substr(md5($_SERVER['REMOTE_ADDR'].microtime().rand(1,100000)),0,6);
        // Generate a random password
        
        $_POST['email'] = mysql_real_escape_string($_POST['email']);
        $_POST['username'] = mysql_real_escape_string($_POST['username']);
        // Escape the input data
        
        
        mysql_query("    INSERT INTO tz_members(usr,pass,email,regIP,dt)
                        VALUES(
                        
                            '".$_POST['username']."',
                            '".md5($pass)."',
                            '".$_POST['email']."',
                            '".$_SERVER['REMOTE_ADDR']."',
                            NOW()
                            
                        )");
        
        if(mysql_affected_rows($link)==1)
        {
            send_mail(    '[email protected]',
                        $_POST['email'],
                        'Registration System Demo - Your New Password',
                        'Your password is: '.$pass);

            $_SESSION['msg']['reg-success']='We sent you an email with your new password!';
        }
        else $err[]='This username is already taken!';
    }

    if(count($err))
    {
        $_SESSION['msg']['reg-err'] = implode('<br />',$err);
    }    
    
    header("Location: index.php");
    exit;
}

$script = '';

if($_SESSION['msg'])
{
    // The script below shows the sliding panel on page load
    
    $script = '
    <script type="text/javascript">
    
        $(function(){
        
            $("div#panel").show();
            $("#toggle a").toggle();
        });
    
    </script>';
    
}
?>

Gracias.