Does anyone have ideas on how to protect a system written on excel, so that the broker or others won't be able to get a copy of it?
Use the Excel Developers kit and code the logic in a XLL, which is a DLL for Excel. You will need to do this in C, C++ . I am not sure if they have a .NET API because I have not written excel addins in about 5 years. They also will let you password protect your code in a XLA, these are protected so you can't see the code but I don't know how easy it is to break them. TradersStudio is a standalone platform and it's language is VBA like. It is a cross between VBA and EasyLanguage. We have password protection also and you can write addins as "COM" DLL so you can do it in VB 6.0. Please take a look at the product overview. It will give your system a much richer presentation. http://www.tradersstudio.com/Overview/tabid/68/Default.aspx
Sorry for the question but....how do you guarantee the customer about TraderStudio that the software does not send back to your servers some code using an open port of Windows?
I think COM DLLs are compiled so you won't easily be able to view the source. If you're worried about it sending your code back to the server (although I doubt they would do this) you could always use a network analyzer to capture all packets sent in and out of your system and look at them to see what data they contain. Paccc
i would think that it is a question of time and effort to crack an excel spreadsheet. i would google around and try to find someone who can cfrack your sheet. if you are successful with that ... well ...
You do not say if the system is written as formulae on a worksheet or with VBA code. Either way, the answer is pretty much the same - Excel is an extremely insecure environment. There is freely available software that you can use to crack the passwords on Excel workbooks,addins etc. So passwords will give you no protection whatsoever. The only real solution is to move your "secrets" into a more secure environment, for example, VB, compile a DLL or XLL, and call this from Excel. It would be almost impossible for anyone to get into your code then.