/*
         *  CreateServerSignature
         */
        public static string AuthorizationCode(string method, string body, string date, string path)
        {
#if UNITY_EDITOR_OSX || (UNITY_IOS && !UNITY_EDITOR_WIN)
            PikkartARCore.CreateUnityServerSignature(method, body, date, path, signaturePtr);
            string signature_str = Marshal.PtrToStringAuto(signaturePtr);
#else
            PikkartARCore.CreateUnityServerSignature(new StringBuilder(method), new StringBuilder(body),
                                                     new StringBuilder(date), new StringBuilder(path), signaturePtr);
            string signature_str = Marshal.PtrToStringAnsi(signaturePtr);
#endif
            if (signature_str != null && signature_str.Length >= SIGNATURE_LENGTH)
            {
                string signature = signature_str.ToString().Substring(0, SIGNATURE_LENGTH);
                return(signature);
            }
            else
            {
                Debug.Log("signature=" + signature_str);
                return("");
            }
        }