How to Lock a PowerPoint File With AES-256 Password Encryption

You need to protect a sensitive PowerPoint file from unauthorized access. PowerPoint uses AES-256 encryption when you set a password to open the file. This article explains how to apply AES-256 password encryption to a PowerPoint file and what to do if the encryption options are missing or grayed out.

How AES-256 Encryption Works in PowerPoint

PowerPoint encrypts presentation files using the AES algorithm with a 256-bit key when you set a password to open the file. AES-256 is the current industry standard for symmetric encryption and is approved by the U.S. government for protecting classified information up to the SECRET level. PowerPoint applies this encryption through the Microsoft Office Document Encryption framework, which is built into Office 2016 and later versions.

The encryption process works as follows. When you set a password, PowerPoint derives a 256-bit encryption key from that password using a key derivation function. The key then encrypts the entire presentation file, including all slides, embedded media, macros, and metadata. Without the correct password, the encrypted file cannot be opened in any application, including older versions of PowerPoint or third-party viewers.

You must use a version of PowerPoint that supports AES-256 encryption. PowerPoint 2016, PowerPoint 2019, PowerPoint 2021, and PowerPoint for Microsoft 365 all support AES-256. PowerPoint 2013 and earlier versions use a weaker encryption algorithm RC4, which is not secure. If you share an AES-256 encrypted file with someone using PowerPoint 2013 or earlier, they will see an error message and cannot open the file.

Steps to Apply AES-256 Password Encryption in PowerPoint

You can encrypt a PowerPoint file using either the Info panel or the Save As dialog. Both methods produce the same AES-256 encryption. Use the Info panel method when you want to encrypt the file you are currently editing. Use the Save As method when you want to create an encrypted copy while keeping the original unencrypted file.

Method 1: Encrypt Through File > Info

1. Open the presentation
   Open the PowerPoint file you want to encrypt in PowerPoint for Microsoft 365, PowerPoint 2021, or PowerPoint 2019.
2. Go to File > Info
   Click the File tab in the ribbon, then click Info in the left sidebar.
3. Click Protect Presentation > Encrypt with Password
   In the Info panel, click the Protect Presentation button. From the drop-down menu, select Encrypt with Password. The Encrypt Document dialog box opens.
4. Enter a strong password
   Type a password in the Password field. Use a password that is at least 12 characters long and includes uppercase letters, lowercase letters, numbers, and symbols. Click OK.
5. Re-enter the password
   In the Confirm Password dialog box, type the same password again. Click OK.
6. Save the file
   Press Ctrl+S or click the Save icon to save the encrypted presentation. The file now requires the password each time it is opened.

Method 2: Encrypt Through Save As > Tools > General Options

1. Open the presentation
   Open the PowerPoint file you want to encrypt.
2. Go to File > Save As
   Click the File tab, then click Save As. Choose a location such as This PC or Browse.
3. Open General Options
   In the Save As dialog box, click the Tools drop-down menu next to the Save button. Select General Options from the list. The General Options dialog box opens.
4. Set the password to open
   In the Password to open field, type your password. Leave the Password to modify field blank unless you also want to restrict editing. Click OK.
5. Confirm the password
   Re-enter the password in the Confirm Password dialog box and click OK.
6. Save the encrypted copy
   Click Save in the Save As dialog box. If the file already exists, PowerPoint asks whether to replace it. Click Yes. The saved copy is now AES-256 encrypted.

If the Encrypt With Password Option Is Grayed Out

PowerPoint Shows Encrypt With Password as Unavailable

The Encrypt with Password option is grayed out when the file is in a format that does not support encryption. The file must be in the .pptx format. Older formats such as .ppt or .pps do not support AES-256 encryption. To fix this, save the file as a .pptx file. Click File > Save As, choose PowerPoint Presentation (.pptx) from the Save as type list, then try the encryption step again.

Encrypt With Password Is Missing Entirely

This option is missing if the file is stored in a location that does not support encryption, such as a SharePoint document library with Information Rights Management enabled, or if the file is currently checked out in a version control system. Save a local copy of the file to your hard drive, then apply the encryption.

Password Dialog Appears but the File Still Opens Without a Password

This happens when you set a password to modify but not a password to open. The password to modify restricts editing but does not encrypt the file. To properly encrypt the file, you must set the password to open field in the General Options dialog box or use the Encrypt with Password option in the Info panel.

PowerPoint Encryption Methods Comparison

Item	Encrypt with Password (Info panel)	Password to open (Save As > General Options)
Encryption algorithm	AES-256	AES-256
Password to modify	Not available	Available as separate field
File format required	.pptx only	.pptx only
Works with PowerPoint 2016 or later	Yes	Yes
Encrypts the current file in place	Yes	No, creates a new copy

You can now encrypt any PowerPoint file with AES-256 password protection using either the Info panel or the Save As dialog. To verify that encryption is active, close the file and reopen it. PowerPoint will prompt for the password before the file opens. For an added layer of security, combine file encryption with Information Rights Management to restrict printing and forwarding of the content.