auth.php

<?php

if (!isset($_GET['username']) || !isset($_GET['password'])) {
    echo 'Missing data!';
} else {
    $state = AuthMeCheck($_GET['username'], $_GET['password']);
    if ($state == 1) {
        echo 'Logged in!';
    } else {
        echo 'Wrong username or password!';
    }
}

function AuthMeCheck($username, $password) {
    $host = "hostname or ip";
    $id = "username";
    $pass = "password";
    $dbn = "database name";
	$db = mysqli_connect($host, $id, $pass, $dbn, 3306);
	$authmeTable = 'authme';
	if($pwd = explode('$', mysqli_fetch_assoc(mysqli_query($db, 'SELECT password FROM '.$authmeTable.' WHERE username="'.$username.'"'))['password']))
		if(strcasecmp(trim($pwd['3']), hash('sha256', hash('sha256', $password).$pwd['2'])) == 0)
			return 1;
}

pretty nice xd