Forum Discussion
Is it really impossible to break workbook protection?
Yes, Excel protection is mainly the protection from the errors due to negligence. Simplest case, if you hide Sheet1 and protect structure, anyone could write in Sheet2 formulas like =Sheet1!A1 and pick-up information from hided sheet in protected structure. To find actual name of the Sheet1 is also not a big deal.
Thanks for your answer. It makes sense. However I have also protected the workbook with a password for opening and anonymised all names with random numbers. Finally I have deleted all content in the hidden worksheets and deleted all previous versions of the workbook before sending to customer. Do you think all this gives 100% protection?
There are password utilities that can crack the encrypted passwords. They typically use brute force method to "guess" the password. If the password is random characters and special characters it makes it very, very hard to guess.