# Are protected Excel 2007 workbooks really secure?



## billpoly (Jan 12, 2009)

Hello-

I have a client that is developing an ROI calculator using Excel 2007.  They are saving the ROI calculator as standard .xlsx and protecting all areas of the workbook that do not require user interaction.  Their plan is to distribute the .xlsx file to customers directly and via their web site.

My question is this... just how secure are Excel 2007 protected workbooks?  My concern is that the ROI calculator contains a great deal of company intellectual property in the calculations - certainly something that would be valuable to competitors.  I don't think Excel 2007 protected .xlsx files are secure enough to distribute with company IP.  Opinions?  Better options?

Best,
Bill


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## SydneyGeek (Jan 12, 2009)

The short answer is NO. Excel is not a secure environment, and was never intended to be. 

VBA code is harder to crack, and harder still if you use .NET code but if you do use .NET, you have distribution issues; all clients neeed to have the appropriate version of the .NET Framework installed. 

If the IP is important, and the client still wants to distribute the workbook, creating custom functions for their ROI calculations (the bits that are their IP) would be one option. Make sure that they password-protect the code. Note though, that custom functions are often slower than the native Excel functions so there could be a performance hit.

Denis


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## billpoly (Jan 12, 2009)

Thanks for the quick reply, Denis.

You confirmed what I suspected - Excel passwords and workbook protection are more of a deterrent to casual attempts than actual security.

Custom functions are above my Excel expertise, but I can certainly research them - thanks for the tip!

I'm also researching ways to take the Excel workbook and convert it to a web app.  This would allow the client to keep the methods secure and only expose a form for input.  I posted a thread elsewhere on the Mr. Excel boards to ask about this...

http://www.mrexcel.com/forum/showthread.php?t=363617

Unfortunately, I'm definitely talking above my pay grade here!   All of the tips and tricks are sincerely appreciated.


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