adding http digest authentication to php5

Can I attach a php script ?

<?php // a sample for digest authentication
$realm="php-users";
$uri = $_SERVER['REQUEST_URI'];
$nonce = time();

$username = "taro";
$password = "secret";

function auth_func() {
global $realm, $nonce;

header('HTTP/1.0 401 Unauthorized');
header("WWW-authenticate: Digest realm="$realm" nonce="$nonce"");
die('password or user name is invalid.');
}

if (empty($_SERVER['PHP_AUTH_USER'])) {
auth_func();
} else {
$username = $_SERVER['PHP_AUTH_USER'];
$response = $_SERVER['PHP_AUTH_PW'];
$nonce = $_SERVER['PHP_AUTH_NONCE'];

// response based on RFC2617
$a1 = md5("$username:$realm:$password");
$a2 = md5("GET:$uri");
$response0 = md5("$a1:$nonce:$a2");

print "response1:$response<br />";
print "response0:$response0<br />";
print "nonce:$nonce</br>";
if ($response == $response0) {
print "authenticated.<br />";
} else {
print "not authenticated.<br />";
}
}
?