How to password protect a PDF on iPhone

1. 1In the Files app, touch and hold the PDF and choose Duplicate. Work on the copy, so you still have an unlocked version.
2. 2Open the copy. It opens in Preview.
3. 3Tap the menu (Actions) next to the file name at the top and choose Lock.
4. 4Enter a password, confirm it and save. The file now asks for the password when someone opens it.

If Lock is not in the menu, your iOS version may not offer it or the file may not be a plain PDF; it is a recent addition to iOS, so update first. Apple's own guide is called Lock PDFs in Preview on iPhone.

The password belongs to the locked file, so it stays with the PDF when you email it or upload it. That is the useful part: you can send the locked copy to an accountant or landlord and give them the password in a separate message or call.

It does not protect the unlocked original, which is still in Files, in Recently Deleted and in any backup that ran before you deleted it. It does not protect copies you shared earlier. And a short or guessable password is the weak point, so pick something long that you do not use anywhere else.

• Deleting the unlocked original before you have tested the locked copy. Open the locked file and enter the password once to be sure it works.
• Forgetting the password. There is no reset: keep it in a password manager or a locked note rather than trusting memory. See how to store passwords safely on your phone.
• Sending the password in the same message as the file. If the message is read by someone else, the lock is gone.

A password on a PDF is made for sending. If the goal is only that nobody who picks up your phone sees an ID scan, a contract or a bank statement, a vault is the better tool. Lockboxy is an iPhone app that keeps files in an encrypted vault with its own passcode.

1. 1Open Lockboxy, go to Files and tap +.
2. 2Choose Import files and pick the PDF, or choose Scan a document to scan paper straight into the vault. You can also send a file in from Files or Mail through the Share Sheet.
3. 3Lockboxy encrypts the file with AES-256 on your device, behind a passcode that is separate from your iPhone passcode. There is no account and no server holding a copy.
4. 4Delete the original. Importing makes a copy; it does not remove the file you picked. Delete it in Files, then empty Recently Deleted.

PDFs open in a preview inside the vault. The vault is for keeping and viewing, so if you need to send the PDF to someone, keep the original or use the locked copy from the first section. How to password protect a folder on iPhone compares this with a locked note and the other built-in options.

• The built-in Lock option is free and does not need an app.
• The free plan of Lockboxy holds up to 10 files; a PDF counts once. Premium removes that limit. Prices are on the Premium page and the app shows the exact price before you buy.
• If you forget the vault passcode and did not set a Recovery Key (Premium), nobody can open the vault, including us.
• Apple can rename menus between iOS versions. If a step does not match your screen, use Search in Settings or the Files app.