How do I use password hashing with PDO to make my code more secure?

Question

My code is actually working but it's not at all secure, I don't want to use MD5 as it's not all that secure. I've been looking up password hashing but I'm not sure how I would incorporate it into my code.

Login:

require_once __DIR__.'/config.php';
session_start();

$dbh = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_USERNAME, DB_USERNAME, DB_PASSWORD);

$sql = "SELECT * FROM users WHERE username = :u AND password = :p";
$query = $dbh->prepare($sql); // prepare
$params = array(":u" => $_POST['username'], ":p" => $_POST['password']);
$query->execute($params); // execute

$results = $query->fetchAll(); // then fetch


//hash passwords pls

if (count($results) > 0 ){
$firstrow = $results[0];
$_SESSION['username'] = $firstrow['username'];
echo "Hello $username you have successfully logged in";
//header ("location:.php");
}
else{
echo "Login Has Failed";
return;
} 

Register:

$dbh = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_USERNAME, DB_USERNAME, DB_PASSWORD);

$username = $_POST["username"];
$email = $_POST["email"];
$password = $_POST["password"];

$stmt = $dbh->prepare("insert into users set username='".$username."', email='".$email."', password='".$password."' ");
$stmt->execute();
echo "<p>Thank you, you are registered</p>";

Could anyone show me how to incorporate it into the code I have?

Answer 1

Just use a library. Seriously. They exist for a reason.

• PHP 5.5+: use password_hash()
• PHP 5.3.7+: use password-compat (a compatibility pack for above)
• All others: use phpass

Don't do it yourself. If you're creating your own salt, YOU'RE DOING IT WRONG. You should be using a library that handles that for you.

$dbh = new PDO(...);

$username = $_POST["username"];
$email = $_POST["email"];
$password = $_POST["password"];
$hash = password_hash($password, PASSWORD_DEFAULT);

$stmt = $dbh->prepare("insert into users set username=?, email=?, password=?");
$stmt->execute([$username, $email, $hash]);

And on login:

$sql = "SELECT * FROM users WHERE username = ?";
$stmt = $dbh->prepare($sql);
$result = $stmt->execute([$_POST['username']]);
$users = $result->fetchAll();
if (isset($users[0]) {
    if (password_verify($_POST['password'], $users[0]->password) {
        // valid login
    } else {
        // invalid password
    }
} else {
    // invalid username
}