EVA

login.php
<?php
session_start();
session_destroy();
$key = "88dc2e7124c2f75681b64a58e71b8a9e";
if( !empty($_POST['key']) && !empty($_POST['user']) )
    if($_POST['key'] == $key)
    {
        $_SESSION['user'] = $_POST['user'];
        header('location: index.php');
    }
?>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Login EVA</title>
</head>

<body>
<form method="post">
<label>Usuário: </label> <input type="text" name="user">
<br>
<label>Key: </label> <input type="text" name="key">
<br>
<input type="submit" name="Enviar">
</form>
</body>
</html>

logoutphp
<?php
unset($_SESSION['user']);
header('location:login.php');
?>


index.php
if( empty($_SESSION['user']) )
    header('location:login.php');
else
    echo "Olá ".$_SESSION['user'];
?>