invite_test.xml

<?xml version="1.0" encoding="UTF-8"?>
<Module>
  <ModulePrefs title="Activity Test" description="Activityのテスト">
    <Link rel="event.addapp" href="http://debian/oauth/t.php" method="POST" />
    <Link rel="event.removeapp" href="http://debian/oauth/t.php" method="POST" />
    <Require feature="opensocial-0.8" />
    <Require feature="dynamic-height" />
  </ModulePrefs>
  <Content type="html"><![CDATA[
Hello!<br />
<a href="#" id="invite">Invite</a>
<script type="text/javascript">
(function(){
  function init()
  {
    document.getElementById("invite").onclick = function() {
      var message = opensocial.newMessage('abc', {});
      opensocial.requestShareApp("VIEWER_FRIENDS", message, function (response) {
      });
    }
    gadgets.window.adjustHeight();
  }
  gadgets.util.registerOnLoadHandler(init);
})();
</script>
]]></Content>
</Module>

t.php

?php
// OpenSocial RSA-SHA1での署名の検証
// ライブラリとして　http://oauth.googlecode.com/svn/code/php/　を利用しています。
include_once 'lib/OAuth.php';

class OAuthSignatureMethod_RSA_SHA1_opOpenSocialPlugin extends OAuthSignatureMethod_RSA_SHA1
{
  protected function fetch_private_cert(&$request) {
    throw new Exception();
  }

  protected function fetch_public_cert(&$request) {
    return <<<EOT
-----BEGIN CERTIFICATE-----
PUBLIC CERT
-----END CERTIFICATE-----
EOT;
  }
}

$request = OAuthRequest::from_request(null, null, null);
$signature_method = new OAuthSignatureMethod_RSA_SHA1_opOpenSocialPlugin();
var_dump($signature_method->check_signature($request, null, null, $request->get_parameter('oauth_signature')));