How to Password Protect a PDF on Mac

Preview can encrypt a PDF so it demands a password before anyone can read it — and separately restrict printing, copying, and editing. Here's how to lock a PDF down, what each of the two passwords actually does, and how to make an unlocked copy again.

Encrypt a PDF in Preview

1. Open the PDF in Preview and choose File → Export…
2. Click the Permissions… button.
3. Check Require Password To Open Document and enter the password readers will need.
4. Below, choose what's allowed without the owner password — printing, copying text, adding annotations, filling form fields — and set an Owner Password at the bottom to enforce those choices.
5. Click Apply, then Save. Export it under a new name so your original stays unlocked on your own machine.

The same options live in the print dialog: File → Print… → PDF → Save as PDF → Security Options… — handy when you're producing the PDF from another app anyway, like locking a Pages invoice or a web receipt as you save it.

Open password vs. owner password

The two passwords do very different jobs, and only one of them is real security:

• The open password encrypts the file. Without it, the contents are unreadable — this is the protection that matters, and its strength depends on the password you pick. Use a long one, and don't send it in the same email as the file.
• The owner password sets permissions — no printing, no copying, no editing. These restrictions are flags that well-behaved PDF apps honor, but plenty of tools ignore them. Treat permissions as a polite request, not a lock.

If you only set an owner password (leaving the file openable by anyone), you've restricted, not protected. For anything sensitive, always set the open password.

Remove a password (make an unlocked copy)

You can only do this for files you can already open:

1. Open the PDF and enter its password.
2. Choose File → Export…, click Permissions…, and uncheck Require Password To Open Document (and clear any owner restrictions).
3. Save under a new name. That copy opens freely.

That's also the undo for this whole guide. One warning deserves repeating: there's no recovery for a forgotten open password — macOS has no back door into an encrypted PDF. Store the password in your password manager the moment you set it.

What this protects — and what it can't

Preview writes standard PDF encryption, so the locked file opens in Acrobat, Windows readers, and browsers — recipients just need the password, not a Mac. But be realistic about the boundaries:

• The filename and file size stay visible. Don't name a confidential file after its confidential contents.
• Once opened, it's readable. Anyone you give the password to can screenshot, retype, or forward the contents. Encryption controls who opens the file, not what they do after.
• The password is the weak point. Short passwords fall to guessing tools regardless of the encryption behind them. A passphrase of four random words beats Summer2025! every time.
• Share the password out-of-band — message or phone, never in the same email thread as the attachment.

Sharing something truly sensitive?

A password stops the wrong people opening the file — but if parts of the document itself must never be seen by the intended recipient either, a password does nothing. Remove those parts for real with Preview's Redact tool before you encrypt: redaction deletes the underlying content, encryption controls the door. The two together cover most document-privacy needs on a Mac.