I have an Excel file with a big worksheet, frequently updated and submitted.
Quite a number of rows and columns are hidden in order to make the calculation details and raw data invisible to people receiving the file, and the sheet is password-protected.
However, a user still might read the hidden part by copying and pasting the content to another sheet, or by using a formula such as
='ProtectedSheet'!J9
where J9 is the hidden cell.
I know every wall has a way to break through, yet still, is there a way to protect the content of a hidden Excel cell from being (easily) read out by a "normal" user?
Best Answer
Farm out the calculation helper cells to a totally different sheet. Then hide that sheet, or use VBA to make it "very hidden" , which means that it cannot be unhidden via the user interface.
This is a quote form John Walkenbach's article http://j-walk.com/ss/excel/usertips/tip036.htm
Protect the VBA project with a password, so even a user with a few VBA skills cannot easily get to it.
Be aware that no Excel password protection is ever totally safe. Worksheet passwords take 2 seconds to disarm. Depending on the Excel version, workbook passwords and VBA passwords can be circumvented with a bit more effort if enough malicious energy is thrown at them.