<?php
session_start(); 
$mdp_crypte = '5ed25af7b1ed23fb00122e13d7f74c4d8262acd8'; // Hash de coucou

if(!isset($_SESSION['connecte']) || $_SESSION['connecte'] != $mdp_crypte){
    header('location: connexion.php');
    exit;
}

?>

Contenu secret...