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How can I better secure my spreadsheet? (Read 1689 times)
Gerrit-Jan Linker
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How can I better secure my spreadsheet?
05.02.10 at 16:41:47
 
How can I better secure my spreadsheet?
 
Quote:
I have prepared a pretty advanced spreadsheet to give to a potential
customer. Because this customer does not have an exclusive agreement with my
company, I would like to build in some security so they cannot see the
calculations and base values.

I tried to hide the sheet with the calculations and protect it. On of our
sales guys was able to break this open in less than 20 minutes.

How can I better secure this?

 
To this end I developed ExcelLock: a locking program to lock and secure the spreadsheet. Basically it encrypts the XLS, it hides all formulas and it securely password protects the file. The file can only be viewed through the ExcelLock viewer (free). When viewed Excel is shown without menus and toolbars or ribbon. You can only view the file and enter values (if you have allowed that).
 
I invite you to have a look at ExcelLock software: www.oraxel.com/projects/excellock
 
I have commented further on your questions below.
 
>I would like to build in some security so they cannot see the
> calculations and base values.  
 
To hide the calculations you should set the appropriate settings in the protection tab of the cell format dialog. ExcelLock will automatically scan for all formulas and do this for you.
 
To hide any base values I suggest you hide the sheet. The user can unhide the sheet however. ExcelLock prevents this by not fully enabling Excel when viewing the file.
 
> I tried to hide the sheet with the calculations and protect it.  On of our
> sales guys was able to break this open in less than 20 minutes.
 
In addition to this you should also consider the scrambling of the data inside the file. Did you know that all the text in the spreadsheet is readable even when you open the .xls in say notepad? For a demonstration, see:
http://www.oraxcel.com/projects/excellock/scramble.html
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Gerrit-Jan Linker
Linker IT Software
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