martin j martin j - 2 months ago 5
PHP Question

Register form minimum characters for password and username

How can i force password and username to have a minimum lenght in PDO?
I could do it my self in a simple input field using PHP, but with this PDO register system I have no clue how to do it, or where to do it. Im not good with PHP and even worse with PDO.

Register form:

<?php
ob_start();
// This if statement checks to determine whether the registration form has been submitted
// If it has, then the registration code is run, otherwise the form is displayed
if(!empty($_POST)) {
// Ensure that the user has entered a non-empty username
if(empty($_POST['username']))
{
// Note that die() is generally a terrible way of handling user errors
// like this. It is much better to display the error with the form
// and allow the user to correct their mistake. However, that is an
// exercise for you to implement yourself. ;
die('
<div class="notice fail">
<div class="notice-p">
Something went wrong!<br />
Please enter a username
</div>
</div><br />
');
}

// Ensure that the user has entered a non-empty password
if(empty($_POST['password']))
{
die('
<div class="notice fail">
<div class="notice-p">
Something went wrong!<br />
Please enter a password
</div>
</div><br />
');
}

// Make sure the user entered a valid E-Mail address
// filter_var is a useful PHP function for validating form input, see:
// http://us.php.net/manual/en/function.filter-var.php
// http://us.php.net/manual/en/filter.filters.php
if(!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL))
{
die('
<div class="notice fail">
<div class="notice-p">
Something went wrong!<br />
Invalid E-mail address.
</div>
</div><br />
');
}

// We will use this SQL query to see whether the username entered by the
// user is already in use. A SELECT query is used to retrieve data from the database.
// :username is a special token, we will substitute a real value in its place when
// we execute the query.
$query = "
SELECT
1
FROM users
WHERE
username = :username
";

// This contains the definitions for any special tokens that we place in
// our SQL query. In this case, we are defining a value for the token
// :username. It is possible to insert $_POST['username'] directly into
// your $query string; however doing so is very insecure and opens your
// code up to SQL injection exploits. Using tokens prevents this.
// For more information on SQL injections, see Wikipedia:
// http://en.wikipedia.org/wiki/SQL_Injection
$query_params = array(
':username' => $_POST['username']
);

try
{
// These two statements run the query against your database table.
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
// Note: On a production website, you should not output $ex->getMessage().
// It may provide an attacker with helpful information about your code.
die('
<div class="notice fail">
<div class="notice-p">
Something went wrong!<br />
Please try agian.
</div>
</div><br />
' . $ex->getMessage());
}

// The fetch() method returns an array representing the "next" row from
// the selected results, or false if there are no more rows to fetch.
$row = $stmt->fetch();

// If a row was returned, then we know a matching username was found in
// the database already and we should not allow the user to continue.
if($row)
{
die('
<div class="notice fail">
<div class="notice-p">
Something went wrong!<br />
Username is already taken.
</div>
</div><br />
');
}

// Now we perform the same type of check for the email address, in order
// to ensure that it is unique.
$query = "
SELECT
1
FROM users
WHERE
email = :email
";

$query_params = array(
':email' => $_POST['email']
);

try
{
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
die('
<div class="notice fail">
<div class="notice-p">
Something went wrong!<br />
Please try again.
</div>
</div><br />
' . $ex->getMessage());
}

$row = $stmt->fetch();

if($row)
{
die('
<div class="notice fail">
<div class="notice-p">
Something went wrong!<br />
This E-mail is already in use by someone ells.
</div>
</div><br />
');
}

// An INSERT query is used to add new rows to a database table.
// Again, we are using special tokens (technically called parameters) to
// protect against SQL injection attacks.
$query = "
INSERT INTO users (
username,
password,
salt,
email
) VALUES (
:username,
:password,
:salt,
:email
)
";

// A salt is randomly generated here to protect again brute force attacks
// and rainbow table attacks. The following statement generates a hex
// representation of an 8 byte salt. Representing this in hex provides
// no additional security, but makes it easier for humans to read.
// For more information:
// http://en.wikipedia.org/wiki/Salt_%28cryptography%29
// http://en.wikipedia.org/wiki/Brute-force_attack
// http://en.wikipedia.org/wiki/Rainbow_table
$salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647));

// This hashes the password with the salt so that it can be stored securely
// in your database. The output of this next statement is a 64 byte hex
// string representing the 32 byte sha256 hash of the password. The original
// password cannot be recovered from the hash. For more information:
// http://en.wikipedia.org/wiki/Cryptographic_hash_function
$password = hash('sha256', $_POST['password'] . $salt);

// Next we hash the hash value 65536 more times. The purpose of this is to
// protect against brute force attacks. Now an attacker must compute the hash 65537
// times for each guess they make against a password, whereas if the password
// were hashed only once the attacker would have been able to make 65537 different
// guesses in the same amount of time instead of only one.
for($round = 0; $round < 65536; $round++)
{
$password = hash('sha256', $password . $salt);
}

// Here we prepare our tokens for insertion into the SQL query. We do not
// store the original password; only the hashed version of it. We do store
// the salt (in its plaintext form; this is not a security risk).
$query_params = array(
':username' => $_POST['username'],
':password' => $password,
':salt' => $salt,
':email' => $_POST['email']
);

try
{
// Execute the query to create the user
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
// Note: On a production website, you should not output $ex->getMessage().
// It may provide an attacker with helpful information about your code.
die('
<div class="notice fail">
<div class="notice-p">
Something went wrong!<br />
Please try again.
</div>
</div><br />
' . $ex->getMessage());
}

ob_clean();
// This redirects the user back to the login page after they register
header("Location: /signin/");

// Calling die or exit after performing a redirect using the header function
// is critical. The rest of your PHP script will continue to execute and
// will be sent to the user if you do not die or exit.
die();

}


//session to store input after die() function
?>

Answer

So, right after your check if the form was submiited, lets see how long those are...

if(!empty($_POST)) {
// check length of $_POST['username']

    if (strlen($_POST['username']) <5){
          die('
                    <div class="notice fail">
                <div class="notice-p">
                Usernames need to be 5 characters or longer
                </div>
            </div><br />
            '); 
    }

  // check length of $_POST['password']

    if (strlen($_POST['password']) <5){
          die('
                    <div class="notice fail">
                <div class="notice-p">
                Passwords need to be 5 characters or longer
                </div>
            </div><br />
            '); 
    }
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