MegaApi.Crypto.base64urldecode C# (CSharp) Метод

        public static byte[] base64urldecode(string data)
        {
            data += "==".Substring((2 - data.Length * 3) & 3);
            data = data.Replace('_', '/').Replace('-', '+').Replace(",", "");
            return Convert.FromBase64String(data);
        }