How to protect Excel formulas from copying
Microsoft Excel offers default formula protection using ‘Hide Excel workbook formula‘ approach. Such Excel formula protection is weak and inefficient. The hidden formulas of Excel workbook can easily be made visible.
The main goal of Excel spreadsheet copy protection is to remove formulas from cells to make them unavailable to anyone. If the formulas are not secured then anyone who get permission to open your Excel workbook, (even if it was protected with password, license key and/or with hardware dongle), may copy all data and formulas (manually or using some software) into another unprotected workbook and use your intellectual property without any restrictions.
The DoneEx XCell Compiler provides the strongest Excel formula protection approach. Excel compiler compiles all Excel formulas from xls into binary code and remove them from the cells of xls (xlsx, xlsm, xlsb) file.
To reach this goal, the calculation engine was created to substitute the original Excel’s calculation in compiled EXE whereas the Excel itself is used for formatting and reflection of calculation results.
This is the only way to really protect Excel formulas.
Even encoding with strong encryption algorithm is not so secure because you should provide decrypt key for user and since this moment your data are decrypted and available for anybody.
- To check if there are any available formulas in any compiled EXE you can switch Excel in “Formula Auditing Mode”.
To do this follow “Main Excel menu” >> “Tools” >> “Formula Auditing” >> “Formula Auditing Mode”
- To check that formulas are not available from VBA code you can use the following equation in VBA
Sheets(“sheet name from your workbook”).Range(“address of cell with formula”).formula
The secured formulas protection is available for any type of DoneEx XCell Compiler licenses . To protect your formulas you just need to compile your xls with DoneEx XCell Compiler.
See also: How to compile your workbook.