function associate($server_url)
{
list($p, $g) = $this->get_mod_gen();
$dh = new DiffieHellman($p, $g, $this->srand);
$cpub = $dh->createKeyExchange();
$args = array('openid.mode' => 'associate', 'openid.assoc_type' => 'HMAC-SHA1', 'openid.session_type' => 'DH-SHA1', 'openid.dh_modulus' => oidUtil::to_b64(oidUtil::long2a($dh->p)), 'openid.dh_gen' => oidUtil::to_b64(oidUtil::long2a($dh->g)), 'openid.dh_consumer_public' => oidUtil::to_b64(oidUtil::long2a($cpub)));
$body = http_build_query($args);
list($url, $data) = $this->http_client->post($server_url, $body);
$results = oidUtil::parsekv($data);
$assoc_type = $this->getResult($results, 'assoc_type');
if ($assoc_type != 'HMAC-SHA1') {
trigger_error(sprintf('runtime error : Unknown association type %s', $assoc_type), E_USER_WARNING);
}
$assoc_handle = $this->getResult($results, 'assoc_handle');
$expires_in = isset($results['expires_in']) ? $results['expires_in'] : 0;
$session_type = isset($results['session_type']) ? $results['session_type'] : 0;
if (!$session_type) {
$secret = oidUtil::from_b64($this->getResult($results, 'mac_key'));
} else {
if ($session_type != 'DH-SHA1') {
trigger_error(sprintf('runtime error : Unknown Session Type: %s', $session_type), E_USER_WARNING);
}
$spub = oidUtil::a2long(oidUtil::from_b64($this->getResult($results, 'dh_server_public')));
$dh_shared = $dh->decryptKeyExchange($spub);
$enc_mac_key = $this->getResult($results, 'enc_mac_key');
// print "enc_mac_key: " . $enc_mac_key;
$secret = oidUtil::strxor(oidUtil::from_b64($enc_mac_key), oidUtil::sha1(oidUtil::long2a($dh_shared)));
}
return ConsumerAssociation::from_expires_in($expires_in, $server_url, $assoc_handle, $secret);
}
