PHP HTTPクライアントでWSSE認証

$created = date('Y-m-d\TH:i:s\Z');

$nonce = pack('H*', sha1(md5(time())));

$pass_digest = base64_encode(pack('H*', sha1($nonce.$created.$pass)));

$wsse =

'UsernameToken Username="'.$user.'", '.

'PasswordDigest="'.$pass_digest.'", '.

'Nonce="'.base64_encode($nonce).'",'.

'Created="'.$created.'"';
$rawdata =

'<xml version="1.0" encoding="UTF-8"?>'.

'<hoge>hogehoge</hoge>';
$req = new HTTP_Request();

$req->setURL($url);

$req->addHeader('Accept','application/x.atom+xml, application/xml, text/xml, */*');

$req->addHeader('WWW-Authenticate','WSSE profile="UsernameToken"');

$req->addHeader('X-WSSE',$wsse );

$req->addHeader('Content-Type', 'application/x.atom+xml');

$req->addHeader('Cache-Control', 'no-cache');

$req->setMethod(HTTP_REQUEST_METHOD_POST);

$req->addRawPostData($rawdata);
$res = $req->sendRequest();

if (PEAR::isError($res)) {

...

}