password_verify() function warned as undefined constant - php

Question

I recently used a format for my login that stored the password in the database using $password = md5(password_1) full code below...
Then changed that to $password = (password_hash($password_1, PASSWORD_DEFAULT); full code below....
it successfully saved a hashed password in my database like:$2y$10$.FTJmF/47NbmQMU3nZGTZeKAHYZ8TBm8X2Jc.TLbAIK...
Now verifying the password is where something is going wrong,
The original code was $password = md5($password_1) which would successfully log me in with the md5 storing in the first code.
I changed that to $password = password_verify($password_1, PASSWORD_DEFUALT);
but thats giving me this error.
Ive tried $hash = password_verify($password_1, PASSWORD_DEFAULT );
but its giving me the same error,
<?php
session_start();
// initializing variables
$username = "";
$email = "";
$errors = array();
// connect to the database
$db = mysqli_connect('', '', '', '');
// REGISTER USER
if (isset($_POST['reg_user'])) {
// receive all input values from the form
$username = mysqli_real_escape_string($db, $_POST['username']);
$email = mysqli_real_escape_string($db, $_POST['email']);
$password_1 = mysqli_real_escape_string($db, $_POST['password_1']);
$password_2 = mysqli_real_escape_string($db, $_POST['password_2']);
// form validation: ensure that the form is correctly filled ...
// by adding (array_push()) corresponding error unto $errors array
if (empty($username)) { array_push($errors, "Username is required"); }
if (empty($email)) { array_push($errors, "Email is required"); }
if (empty($password_1)) { array_push($errors, "Password is required"); }
if ($password_1 != $password_2) {
array_push($errors, "The two passwords do not match");
}
// first check the database to make sure
// a user does not already exist with the same username and/or email
$user_check_query = "SELECT * FROM loginsystem WHERE username='$username' OR email='$email' LIMIT 1";
$result = mysqli_query($db, $user_check_query);
$user = mysqli_fetch_assoc($result);
if ($user) { // if user exists
if ($user['username'] === $username) {
array_push($errors, "Username already exists");
}
if ($user['email'] === $email) {
array_push($errors, "email already exists");
}
}
// Finally, register user if there are no errors in the form
if (count($errors) == 0) {
//Hashing the password
$password = password_hash($password_1, PASSWORD_DEFAULT);//encrypt the password before saving in the database
$query = "INSERT INTO loginsystem (username, email, password)
VALUES('$username', '$email', '$password')";
mysqli_query($db, $query);
$_SESSION['username'] = $username;
$_SESSION['success'] = "You are now logged in";
header('location: home.php');
}
}
// ...
// ...
// LOGIN USER
if (isset($_POST['login_user'])) {
$username = mysqli_real_escape_string($db, $_POST['username']);
$password = mysqli_real_escape_string($db, $_POST['password_1']);
if (empty($username)) {
array_push($errors, "Username is required");
}
if (empty($password)) {
array_push($errors, "Password is required");
}
if (count($errors) == 0) $password = password_verify($password, PASSWORD_DEFAULT); {
$query = "SELECT * FROM loginsystem WHERE username='$username' AND password='$password'";
$results = mysqli_query($db, $query);
if (mysqli_num_rows($results) == 1) {
$_SESSION['username'] = $username;
$_SESSION['success'] = "You are now logged in";
header('location: index.php');
}else {
array_push($errors, "Wrong username/password combination");
}
}
}
?>

Answer 1

apart from the typos there are two problems:
1st: password_verify() has different parameters: the typed password and the hashed password from database.
which leads us to the second problem:
You can only verify the password after you got the hash from the database.
So get that hash first (by querying for usename alone), than verify.
$query = "SELECT username, email, password FROM loginsystem WHERE username='$username'";
$results = mysqli_query($db, $query);
if (mysqli_num_rows($results) == 1) {
$row = mysqli_fetch_assoc($results);
if(password_verify($password, $row['password'])) {
// password correct!
} else {
// nope
}
} else {
// wrong credentials
}
You should also change to a prepared statements, as this now could be vulnerable to sql injection.

Answer 2

PASSWORD_DEFUALT is misspelled. It should be PASSWORD_DEFAULT as in the example below:
$hash = password_hash($password, PASSWORD_DEFAULT);
[...]
if (password_verify($password, $hash)) {
// Password matches
}
The first parameter of password_verify is the user-entered password. The second parameter is the stored hash generated by password_hash.