Securing data is a tiered process, with password-protection at the file level, as the bottom level. It's a first step effort, but certainly not the only step you should take to protect confidential and proprietary data. Password protecting an Excel workbook (file level) controls access in two ways: It lets a user in and it lets a user save changes.
Before we discuss Excel's password protection feature, let's clarify just what we mean by security. Although the terms security and protection are bantered about interchangeably, feature-wise in Excel, they aren't the same thing. Security lets you choose who gets in and by virtue of doing so, who doesn't. Protection limits users who are already in. Security is about access, protection is about maintaining integrity.
To assign a password to an Excel workbook, do the following:
- From the File menu, choose Save As. In Excel 2007, click the Office button and choose Save As. In 2010, click the File tab and choose Save As.
- Click the Tools dropdown on the dialog toolbar and choose Save Options. In Excel 2007 and 2010, click the Tools dropdown (in the bottom left corner of the dialog box). In Windows 7, the Tools dropdown will be just to the left of the Save button.
- In the resulting dialog, you can set two passwords: one to open the workbook and one to modify the workbook. Advanced options let you set encryption options for added security.
- Enter one or both passwords and click OK.
- Confirm each password and click OK.
- Click Save.
Setting a password to open the workbook is self-explanatory; if a user doesn't know the password, he or she can't open the file. That gives you a great deal of control, if you do a reasonable job of securing passwords. Of course, you can't really do anything about the user who shares a password, but that's an altogether different problem. Just remember that this password only keeps users out; a user that knows this password has access to all the data and can modify the data once in.
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That's where the second password comes in. By assigning this password, you can allow users to open the workbook and view the data, but withhold permission to actually modify the workbook. A user who knows this password can view and modify data and also save changes to the workbook.A user who doesn't know the password can still view the data, but it's Read-Only—sort of. This user can still modify data, but the password-protected workbook won't let the user save changes—sort of. Here's the deal: A user without the modifying password can still view, modify, and save changes, if the user can get in. This user just can't save the changes to the protected workbook. The user can however, enter a new name and create a new workbook. Important considerations
Before you start password protecting all your workbooks, there are three important things to keep in mind:
- Anyone with the password to modify the workbook can also remove the password protection! Use this particular option wisely.
- Casual users won't have the expertise to crack your password, but anybody can purchase password-cracking software. Your best protection against this type of tampering (or outright theft) is to assign a ridiculously long password of random characters. Doing so won't defeat specialized software, but it will slow it down and that delay might cause the would-be cracker to put your workbook aside. On the other hand, it's sure to annoy your valid users. Balancing the two needs can be a bit of a high-wire act. For more on this subject, read Strong passwords--realistic or burdensome.
- If you forget your password, you can't get into your workbook and make changes, but you can purchase the password-cracking software.
Excel's password protection is a great feature and fortunately, it's easy to implement. Just don't confuse it with sheet protection and by all means, don't rely solely on it to secure sensitive data.
Susan Sales Harkins is an IT consultant, specializing in desktop solutions. Previously, she was editor in chief for The Cobb Group, the world's largest publisher of technical journals.