auth.php

<?php
if (!(
    isset($_SERVER['PHP_AUTH_USER'])
    && 'username' == $_SERVER['PHP_AUTH_USER']
    && isset($_SERVER['PHP_AUTH_PW'])
    && sha1('password') == sha1($_SERVER['PHP_AUTH_PW'])
)) {
    header('WWW-Authenticate: Basic realm="Orchestra"');
    header('HTTP/1.0 401 Unauthorized');
    echo "You must authenticate to use this site.\n\n";
    exit;
}