C# prevent excel file from getting modified <p>Hi I'm searching a way to <strong>prevent</strong> an <strong>excel file</strong> from being <strong>modified</strong>. I <strong>don't want to use hidden fields</strong>, where you have to place a calculated hashcode in.</p> <p>My program should be able to note that a file has been modified outside the application when I reopen the file. </p> <p><strong>EDIT: Sorry i forgot to mention I also don't want to use a password</strong>, because the excel file may be only edited in the application and not outside...</p> <p>Is there a solution for this?</p> <p>Thanks in advance</p>