How to Password Protect a PDF with PDFEncrypt

PDFEncrypt is a free, open-source Windows app that encrypts PDF files locally using standard PDF encryption, so you can set an open password and permission options without buying Adobe Acrobat or uploading confidential files to a third-party server. It runs on Windows 7, 8, 10, and 11. The steps below apply to the current release (version 1.1.8462.22528, released 2023), which supports owner passwords and command-line arguments.

Before you start

• Operating system: Windows 7, 8, 10, or 11.
• .NET Framework: The standard installer includes it; there is also an installer without .NET Framework if your machine already has it.
• No installer needed: A Portable Edition is available if you can't or don't want to install software.
• Source of the app: Download from pdfencrypt.net, the Microsoft Store, or build from the source code on GitHub. The app uses the iTextPDF open-source library and is released under the AGPL license.

Step-by-step: encrypt a PDF

1. Get PDFEncrypt onto your PC

Choose one of these options from the download page:

Each download lists a SHA1SUM you can use to verify the file after downloading.

2. Open the app and select your PDF

Launch PDFEncrypt and choose the PDF file you want to protect. The app works on any standard PDF document.

3. Set the user password (required to open)

Enter the password a reader must supply before the document can be viewed in Adobe Reader or Adobe Acrobat. Without it, the encrypted contents are unreadable. This is the password you'll share with anyone who needs to open the file.

4. Configure the owner password and permissions

The owner password controls changes to the document and works together with the permission options. Depending on what you need, you can restrict actions such as printing and copying. Set these according to how much control you want to keep over the file after it leaves your hands.

5. Encrypt and save

Run the encryption and save the output file. The result is a new encrypted PDF; the original is unaffected. When someone opens the encrypted file, they must enter the user password before the contents appear.

6. Verify before you share

Open the saved file in Adobe Reader or Adobe Acrobat and confirm:

• It prompts for the password.
• The password you set works.
• The permissions you chose behave as expected (for example, printing is blocked if you disabled it).

What PDFEncrypt is not for

PDFEncrypt's own documentation addresses Digital Rights Management (DRM) directly: users often ask how to create PDFs that open without a password but still can't be copied or misused. The site's DRM article explores whether the app is suitable for that goal, so if your requirement is "open freely but restrict copying," read that article before assuming a simple password setup will do it. Password-based encryption and DRM are not the same thing.

Common snags

• Reader still asks for a password after you set permissions only: The user password is what gates opening. If you want the file to open without a prompt, that's the DRM scenario above, not standard password protection.
• Installer fails on a fresh machine: Try the standard installer, which bundles .NET Framework, rather than the no-.NET version.
• You need to deploy across many PCs: An MSI package (beta) exists for Windows Active Directory, tested on Windows 10 x64 and Windows 11 x64. Note it does not include .NET Framework.
• You want to automate encryption: The 2023 release added command-line arguments, so batch or scripted encryption is possible.

Quick decision guide

• Just need a password to open a PDF, on your own Windows PC, for free: Use the standard installer or Portable Edition and set a user password.
• Need to control printing/copying: Add an owner password and adjust the permission options.
• Can't install software: Use the Portable Edition.
• Managing many machines: Consider the MSI (beta) or the command-line arguments.
• Need files to open without a password but stay restricted: Review the DRM article first; this may not match what PDFEncrypt does.