PHP Authentication over HTTP

<?php
if (!isset($_SERVER['PHP_AUTH_USER'])) {
header("WWW-Authenticate: Basic realm=\"Private Area\"");
header("HTTP/1.0 401 Unauthorized");
print "Sorry - you need valid credentials to be granted access!\n";
exit;
} else {
if (($_SERVER['PHP_AUTH_USER'] == 'paul') && ($_SERVER['PHP_AUTH_PW'] == 'hudson')) {
print "Welcome to the private area!";
} else {
header("WWW-Authenticate: Basic realm=\"Private Area\"");
header("HTTP/1.0 401 Unauthorized");
print "Sorry - you need valid credentials to be granted access!\n";
exit;
}
}
?>

[ad code=4]