Cloudinary::sign_request PHP 메소드

    public static function sign_request($params, &$options)
    {
        $api_key = Cloudinary::option_get($options, "api_key", Cloudinary::config_get("api_key"));
        if (!$api_key) {
            throw new \InvalidArgumentException("Must supply api_key");
        }
        $api_secret = Cloudinary::option_get($options, "api_secret", Cloudinary::config_get("api_secret"));
        if (!$api_secret) {
            throw new \InvalidArgumentException("Must supply api_secret");
        }
        # Remove blank parameters
        $params = array_filter($params, function ($v) {
            return isset($v) && $v !== "";
        });
        $params["signature"] = Cloudinary::api_sign_request($params, $api_secret);
        $params["api_key"] = $api_key;
        return $params;
    }

 function cl_form_tag($callback_url, $options = array())
 {
     $form_options = Cloudinary::option_get($options, "form", array());
     $options["callback_url"] = $callback_url;
     $params = Cloudinary\Uploader::build_upload_params($options);
     $params = Cloudinary::sign_request($params, $options);
     $api_url = Cloudinary::cloudinary_api_url("upload", $options);
     $form = "<form enctype='multipart/form-data' action='" . $api_url . "' method='POST' " . Cloudinary::html_attrs($form_options) . ">\n";
     foreach ($params as $key => $value) {
         $form .= "<input " . Cloudinary::html_attrs(array("name" => $key, "value" => $value, "type" => "hidden")) . "/>\n";
     }
     $form .= "</form>\n";
     return $form;
 }