Workbook.Protect Method (Object, Object, Object)
Protects a workbook so that it cannot be modified.
Assembly: Microsoft.Office.Tools.Excel (in Microsoft.Office.Tools.Excel.dll)
A case-sensitive password for the workbook. If this argument is omitted, you can unprotect the workbook without using a password. Otherwise, you must specify the password to unprotect the workbook.
true to protect the structure of the workbook (the relative position of the sheets). The default value is false.
true to protect the workbook windows. If this argument is omitted, the windows are not protected.
Use strong passwords that combine uppercase and lowercase letters, numbers, and symbols. Weak passwords do not mix these elements. For example, "Y6dh!et5" is a strong password, but "House27" is a weak password. Use a strong password that you can remember so that you do not have to write it down.