Authenticating a user using mysqli and password_verify()

1. Comments (1)

That's extremely popular question on various forums and Stack Overflow. And at the same time it's a very good example that can show you how to use Mysqli properly.

First of all make sure that your passwords are stored in the database using password_hash() function.

Then, given $conn variable contains a valid mysqli instance (here you can see how to connect with mysqli properly), the code to check the password will be as simple as that:

$stmt = $conn->prepare("SELECT * FROM users WHERE email = ?");
$stmt->bind_param("s", $_POST['email']);
$stmt->execute();
$user = $stmt->get_result()->fetch_assoc();

if ($user && password_verify($_POST['pass'], $user['pass']))
{
    // credentials are OK, add user in a session etc...;
} else {
    // login failed;
}

Here we are checking in one condition whether a user exists and whether the password is correct.

Note that is is not advised to provide a distinct error message if a user not found. Just a generic "Credentials are not correct" would be enough. Otherwise it will help a malicious user to find whether a certain email is registered on the site.