How to Password-Protect Microsoft Word, Excel and PowerPoint Documents

As we’ve discussed numerous times, you should encrypt any sensitive file to deter would-be data thieves or snoops. That is especially important for shared computers or laptops that are exposed to greater risk. Although encrypted containers and drives offer a fantastic option for protecting multiple files, the files are fully exposed while the container is mounted. Likewise, encrypted ZIP files are great, but you have to extract the files to modify them.

To fill those gaps, use Microsoft Office’s integrated, per-file, password protection. Just be sure you’re using a modern version of Office, because prior to 2007, the encryption algorithm was just silly easy to crack. However, Microsoft implemented 128-bit AES encryption by default with Office 2007 and upgraded that to 256-bit with Office 2016. That should be more than enough for most users, so long as you use a strong password.

The encryption methods for Word, Excel and PowerPoint are all essentially the same, so I’ll just walk you through one of those: Word 2016. Also notice in the title I say “password protect,” rather than “encrypt.” That’s because Office offers two password protection options, but only one actually encrypts the data:

  1. Password to Open fully encrypts the file and prevents it from being opened or viewed without the correct password. This is the method you want to use to protect sensitive data. It is “password protected” and “encrypted.”
  2. Password to Modify does not encrypt the data; it simply requires a password be entered before modifying the documents, I.e., it’s read-only. However, it doesn’t stop anyone from viewing the information unless you additionally have open protection enabled. Keep in mind, circumventing modify protection is trivial for a knowledgeable attacker, so you should not rely on it to protect your data. Hence, this is “password protected” (arguably) but not “encrypted.”

A third option is to use both methods, so it does indeed encrypt the file and requires a second password before you can modify it.

Encrypt With Password

This method fully encrypts the document and prevents unauthorized users opening or viewing the information. However, this only gives you the option to apply open protection, not modify protection. If you need both or just modify protection, use the second method instead.

1. Click the File tab to access file-related options.
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2. Click Info > Protect Document > Encrypt With Password.
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3. Choose a password, enter it the Password field and click OK.
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Remember to choose a good password to protect your sensitive data. If you later want to remove protection, simply leave the Password field blank when performing these steps.

4. Re-enter the same password to confirm you typed it correctly.
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5. Click Save to enable the new password.
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If you prefer to keep an original, unprotected copy, choose Save As and choose a different file name. You might consider this option if you want to keep a local, unprotected copy, but need a new, protected one to email.

Password to Open and/or Modify

This enables you to apply protection against opening and/or modifying. Keep in mind modify protection does not actually encrypt the data and could be circumvented by a tech-savvy user, so it’s only reliable to prevent accidental changes.

1. Click the File tab.
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2. Click Save As and choose a save location.
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3. Keep the same name to overwrite the original with a protected version, or choose a new name to have a protected and unprotected version.
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In this case, I chose to append “-protected” to create a new, protected copy.

4. Click Tools > General Options.
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5. Choose a strong password(s), enter it in the Password to Open and/or Password to Modify fields, and click OK.
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In this case, I’m only adding a password for modifying the document.
Additional Notes:

  • The Password to Open and Password to Modify passwords can be the same, and you’ll still need to enter it when opening and allowing modifications. However, it makes more sense to have these passwords different, so you can allow some users to read the document without immediately knowing how to edit it as well.
  • Leaving a field blank will remove that protection.

6. Re-enter the password and click OK.
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If you added a password for opening and modifying, you’ll need to confirm both: first the open password, then the modify password.

7. Click Save.
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