Encryption Features come built into all the Microsoft Office 2010 Suite of applications including Word 2010, Excel 2010, and Powerpoint 2010. This feature is a nice improvement over password protecting documents under Office 2007 since it is also password protected – but the new process for Office 2010 is consistent across the core Office suite (Word 2010, Excel 2010, PowerPoint 2010, etc.) I’ll demonstrate the process just once using Microsoft Word 2010.
Editor Update 7/25/2012 – I recently documented the same process here for Office 2013 users. Enjoy!
How To Password Protect A Word or Excel Document Using Built-in Office Encryption
Step 1 – Click the File tab, then Click Info. On the menu to the right Click Protect Document and Click Encrypt with Password.
Step 2 – The Encrypt Document dialog will appear, Type in a strong password and then Click OK to finish.
Please note – It’s critical to use a strong password or passphrase step #2. Yeah yeah… you don’t need to get crazy here with wild $ymb0ls and upper and lower case characters which you will forget in 10 minutes. However, using a simple dictionary word will allow anyone with a $100 password cracking app to gain access to your document. Using a long passphrase, however (IE: my house is yellow) with 10 or more characters will significantly increase the encryption strength of the document. This method will decrease the likelihood that someone will be able to break the encryption and gain access to your document. I’ve written a detailed article on strong passwords and passphrases so be sure to check it out before you choose a password for step 2.
Select a password to protect your document!
If you’re looking to password-protect your document for sharing purposes (Set a Password to Open or Password to Modify option), you will have to use the OLD Password Protection dialog used with previous versions of Office. For that step-by-step, take a look at this article I wrote for Office 2007.