I found an easy way to solve the SSL-certificat problem:
add_action('http_api_curl',array(&$this, 'modify_curl'));
function modify_curl($handle){
curl_setopt ( $handle , CURLOPT_CAINFO , dirname(__FILE__).'/cacert.pem' );
}
And I got the Certificates from here: https://curl.haxx.se/ca/cacert.pem and put it in the browserid directory.