How to password protect a PDF on iPhone
Apple documents locking a PDF in Preview on iPhone: open the file, tap the Actions menu next to the file name, tap Lock and set a password. That protects one file with one password. A Vault protects a whole folder of files and hides their names. Either way, the strength of the password decides how much protection you get.
Lock a PDF in Preview
Apple's iPhone guide describes these steps:
- Open the PDF in Preview.
- Tap the Actions menu next to the file name, then tap Lock.
- Enter a password and enter it again in the Verify field. The Require Password setting turns on automatically.
- Tap Done to apply, or Close to cancel.
Apple recommends keeping an unlocked copy first: tap the Actions menu and tap Duplicate. If you forget the password you may lose access to the file, so store the password somewhere safe (a password manager is the usual place).
The part of Apple's page that I could confirm describes the lock as protecting your work from being edited or deleted by others. It does not spell out in the text I could read exactly what a person sees if they try to open the file. Test it: send yourself the locked copy, open it in another app and see what is asked for.
What a PDF password does and does not do
- It protects one file. Every other file in the folder stays as it was.
- It does not hide the file name, which can say a lot (
passport-scan.pdf). - It is only as strong as the password. A short or familiar word is easy to guess; a long passphrase is much harder. A password manager can generate and keep one for you.
- Once you open the file and share it, the copy you send is whatever you send. Share the locked file, not an opened export, if you want the lock to travel.
- It does not stop someone holding your unlocked phone from seeing the file in Files.
When a Vault fits better
If you have a dozen PDFs, setting twelve passwords is a chore, and each name is still readable. A Vault is encrypted as a whole, with one pattern or passphrase, and file names live inside it. Import PDFs from Files, group them in folders and view them in the app. The trade: the Vault has no cloud copy, so you need your Recovery Phrase and an Export Package.
A fair way to combine them: lock the PDF you must send to someone, using a password you tell them separately, and keep your own master copies in the Vault.
- Folders in a Vault
- Export Package
- Back to the pillar guide
- Locking the Files app
- What is a Recovery Phrase
- What StrongRoom does not protect against
Frequently asked questions
Can I password protect a PDF in the Files app?
Apple's iPhone guide that I found describes locking in Preview. I did not find a Files-specific lock in Apple's documentation, so this guide does not describe one.
What if I forget the PDF password?
You may not be able to open the file. Keep the password in a password manager and an unlocked duplicate somewhere safe.
Is a locked PDF as private as a Vault?
No. A lock covers one file and leaves the name visible. A Vault encrypts everything in it under one credential.
Sources
- Lock PDFs in Preview on iPhone (Apple Support), checked on 2026-10-30 (steps taken from the search result summary of this page; the page body itself did not load in full).