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Top 3 Ways | How to Encrypt a PDF in 2025

Secure your PDFs in 2024 with three reliable methods: PurePDF's Protect PDF tool, Adobe Acrobat/Preview, and free command-line qpdf. Step-by-step, plus tips and FAQs.

January 12, 2026•4 min read

Top 3 Ways | How to Encrypt a PDF in 2024

Encrypting PDFs is essential for protecting sensitive information, sharing documents securely, and complying with privacy rules. This guide covers the top 3 ways to encrypt a PDF in 2024 — including a recommended, easy, and secure option using PurePDF's Protect PDF tool — with step-by-step instructions, quick tips, and FAQs.

Why encrypt a PDF?

Encrypting a PDF prevents unauthorized viewing, copying, printing, or editing. Modern PDF encryption uses strong algorithms like AES-256, which keep personal data, contracts, invoices, and confidential reports safe when shared or stored.

Method 1 — PurePDF Protect PDF (Recommended)

PurePDF's Protect PDF tool is built for speed, security, and simplicity. It supports AES-256 encryption, batch processing, and fine-grained permissions (viewing, printing, copying, form filling). Use it in your browser or via API/CLI for automation.

  1. Visit the PurePDF Protect PDF page (protect-pdf).
  2. Upload your PDF file (single or multiple files for batch protect).
  3. Choose an encryption level (AES-256 recommended) and set a user password. Optionally set an owner password and permissions (prevent printing, copying, etc.).
  4. Click "Protect" and wait for processing (usually seconds). PurePDF encrypts and returns a downloadable file.
  5. Download the encrypted PDF and verify the password and permissions by opening it.

Benefits of PurePDF:

  • Fast, browser-based — no local software install required.
  • AES-256 encryption and customizable permissions.
  • Batch processing, API and CLI for automation.
  • Clean interface and reliable file handling.

Method 2 — Adobe Acrobat Pro / macOS Preview (GUI)

For users with Adobe Acrobat Pro or macOS Preview, you can encrypt without third-party services. Adobe offers very granular control; Preview provides a quick password option for mac users.

Adobe Acrobat Pro (Windows/Mac):

  1. Open the PDF in Acrobat Pro.
  2. Go to File > Protect Using Password (or Tools > Protect > Encrypt).
  3. Choose whether you want a password to open the document (user password) or to restrict editing/printing (permissions/owner password).
  4. Select encryption settings (AES-256 recommended) and enter passwords.
  5. Save the PDF.

macOS Preview:

  1. Open the PDF in Preview.
  2. Choose File > Export as PDF.
  3. Check "Encrypt" and enter a password.
  4. Save the encrypted PDF.

Notes:

  • Adobe Acrobat Pro is paid software but feature-rich.
  • Preview is fast for basic password protection but less configurable.

Method 3 — qpdf (Free Command-Line, Power Users)

qpdf is a lightweight, open-source tool for encrypting and modifying PDFs. Ideal for automation on servers, CI pipelines, and power users.

  1. Install qpdf (macOS: brew install qpdf; Linux: apt/yum install qpdf; Windows: download binary).

  2. Encrypt with a single command:

    qpdf --encrypt user-password owner-password 256 -- input.pdf output-encrypted.pdf

  3. Verify by opening the output file and entering the user password.

Notes:

  • qpdf supports AES-256 and scripting for batch workflows.
  • No GUI — command-line knowledge required.

Quick Tips

  • Always choose AES-256 for strong encryption unless compatibility requires AES-128.
  • Use a strong password (12+ characters, mix of letters, numbers, symbols). Consider a password manager.
  • Test the encrypted file on a separate device or reader to confirm password and permissions work as expected.
  • For bulk workflows or automated systems, use PurePDF's API or qpdf scripting.
  • Keep an unencrypted backup if you might forget the password — password recovery for PDF encryption is often impossible.

FAQs

Q: Is encrypting a PDF the same as password-protecting it? A: Yes — in common use, "encrypting" and "password-protecting" a PDF mean requiring a password to open or to change permissions. Proper encryption uses strong algorithms like AES-256.

Q: Can I remove a password from a PDF I encrypted? A: If you have the owner or user password, yes — you can remove it with the same tool you used to set it (PurePDF supports removing protection if you provide the password). Without the password, removal may be impossible or require lengthy attacks.

Q: Will encryption affect PDF features like forms or signatures? A: Encryption can affect interactivity. When setting permissions, allow form filling and signing if you need those features. Some signature types require the document to be unaltered after signing.

Q: Is PurePDF secure for confidential documents? A: PurePDF uses strong encryption standards (AES-256) and secure processing. For extremely sensitive documents, check your organization’s compliance needs and consider on-premise or enterprise offerings; PurePDF also provides API and enterprise plans for controlled workflows.

Which method should I choose?

  • Choose PurePDF Protect PDF if you want a fast, secure, no-install, user-friendly solution with batch processing and API automation.
  • Choose Adobe Acrobat Pro if you need the most granular GUI controls and advanced PDF editing features.
  • Choose qpdf for free, scriptable encryption in automated or server-side environments.

PurePDF makes encrypting PDFs in 2024 simple and secure. Whether you need one-off protection in the browser, batch processing, or an API for automation, PurePDF Protect PDF is built to save time while keeping your documents safe.

If you’re ready to encrypt a PDF now, try PurePDF Protect PDF (protect-pdf) and secure your documents in a few clicks.