everyday mac tools

Password protect a PDF on a Mac before you email it

· 7 min read

You can password protect a PDF on a Mac without installing anything. Open it in Preview, choose File, Export, click Permissions, tick “Require Password to Open Document” and set a password, then save the new copy. Anyone who opens that file will be asked for the password first.

The steps take a minute. The part worth slowing down for is what the password actually protects, because a PDF can carry two different kinds of password and only one of them keeps the contents private.

Two kinds of PDF password

A PDF can have an open password (sometimes called a user password) and a permissions password (sometimes called an owner password).

The open password encrypts the document. Without it, the file cannot be read at all; the pages are not sitting there in plain text waiting for someone to look. This is the one you want when you are sending a tax return, a contract or a medical letter.

The permissions password sets rules: no printing, no copying text, no editing. Those rules are only as strong as the software reading the file. Well-behaved PDF apps honor them; plenty of tools ignore them. Treat permissions as a polite request, not as security. If a document must not be copied, the real protection is not sending it, or sending a version with the sensitive parts removed.

Everything below focuses on the open password.

Method 1: Preview’s Export dialog

On recent versions of macOS:

  1. Open the PDF in Preview.
  2. Choose File, Export (not Export as PDF, which has fewer options).
  3. Make sure Format is set to PDF.
  4. Click Permissions.
  5. Tick “Require Password to Open Document” and type the password twice.
  6. Preview also asks for an owner password, which controls who can change the permissions later. Use a different password from the open one and keep it somewhere safe.
  7. Click Apply, give the file a new name such as contract-protected.pdf, and click Save.

Saving under a new name matters. You keep an unprotected original for yourself and send only the protected copy. If you overwrite the original and later forget the password, there is no recovery path.

On older versions of macOS the Export dialog shows an “Encrypt” checkbox with password fields instead of a Permissions button. It does the same job.

Method 2: the Print dialog, from any app

If the document is not a PDF yet, for example a page in a word processor or a web page, you can create a protected PDF in one step from almost any app.

  1. Choose File, Print.
  2. At the bottom of the dialog, open the PDF menu and choose Save as PDF.
  3. Click Security Options.
  4. Tick “Require password to open document” and enter the password twice. You can also restrict copying and printing here, with the caveat above.
  5. Click OK, name the file and save.

This route is handy for a one-off document you are about to email, since it skips the step of making an unprotected PDF first. Pages, Numbers and Keynote also offer a “Require password to open” option when you export to PDF.

Choosing and sending the password

The encryption is only as good as the password, and the password is only as private as the channel it travels through.

Make it long, not clever. Three or four unrelated words beat a short string of symbols. A PDF can be copied and attacked offline at leisure, so a short password is a weak one.

Never send it in the same email. If the email is misdelivered or the account is compromised, the attacker gets both the file and the key. Send the password by text message or say it on a phone call.

Agree on a pattern for repeat recipients. If you send an accountant documents every month, agree a password in person once and reuse it for that relationship only.

Check before you send. Open the protected copy in Preview. It should ask for the password before showing a single page. If it opens straight away, the setting did not take.

What a password does not fix

A password controls who can open a file. It does nothing about what is inside once they have. Before protecting and sending something sensitive, two checks are worth a minute.

Hidden information. PDFs carry author names, software details, revision history and sometimes attachments or earlier layers. Remove metadata from a PDF on a Mac before you share it covers what to strip.

Things the recipient should not see at all. If part of the document is none of their business, a password is the wrong tool; the recipient will unlock it and read everything. Remove that part properly first. Redact a bank statement before sending it walks through a common case, and it explains why drawing black boxes over text is not the same as removing it.

If you protect PDFs regularly, Basalt is a native Mac PDF app with a Passwords tool for adding or removing a password, alongside redaction, metadata inspection and clean-up in the same window. Like every Basalt tool it writes a new file and never modifies the original, so the unprotected copy you keep is exactly what you started with. It runs entirely on the Mac with no account and no upload, which matters when the whole point is keeping a document private. It will not open a PDF whose password you do not have. Preview is perfectly adequate for the occasional file.

When the recipient no longer needs protection, or you receive a protected file of your own, remove the password from a PDF you own covers the reverse.

Questions

Is Preview’s password protection real encryption? Yes. An open password makes Preview save the document encrypted, so the pages cannot be read without it. The permissions options are the weaker part, because they rely on the reading app to obey them.

Can I password protect a PDF without changing the original? Yes, and you should. Always save the protected version under a new name. Both Preview’s Export and the Print dialog create a new file when you give it a new name.

What if I forget the password? There is no reset. If you kept an unprotected original, protect it again with a new password. If you did not, the protected copy is effectively lost, which is the whole reason to keep the original.

Will the recipient need special software? No. Any standard PDF reader on a Mac, Windows PC, phone or tablet will prompt for the password and then open the file normally.