Google Service Account PKCS12 Fingerprint

// Read the Google Services Account pkcs12 key and return the fingerprint.
// This is not important for functionality, but will allow the user to
// cross-reference their uploaded fingerprint with the one displayed in the
// Google credentials management page.
function get_google_services_key_fingerprint () {
	global $google_services_key_path;
	$certs = array();
	openssl_pkcs12_read(file_get_contents($google_services_key_path), $certs, "notasecret");
	if (sizeof($certs) > 0) {
		$output = $certs['cert'];
		$output = preg_replace('/\-{5}[A-Z\ ]*\-{5}/', '', $output);
		return sha1(base64_decode($output));
	}
	return '';
}