How to Lock a PDF With a Password on iPhone
Yes, iOS 27 can do this without an app. Open the PDF in Apple's Preview app, tap the button by the filename, then tap Lock.
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What do I need to know?
- Make a copy first. Apple's own steps say to duplicate the PDF if you want an unlocked version.
- Test the lock before you rely on it. Send the locked copy to yourself and open it somewhere else.
- The unlocked original still exists. Delete it, or the password protects nothing.
How do I lock a PDF in Preview? (iOS 27)
These steps follow Apple's guide to locking PDFs in Preview.
- Open the Preview app and open the PDF.
- To keep an unlocked copy, tap the menu button, then tap Duplicate.
- Tap the button next to the filename, then tap Lock.
- Type the same password in Password and Verify. Require Password turns on by itself.
- Confirm to apply the change.
Apple describes this lock as a way "to prevent others from editing or deleting your work". Before you send the file, open the locked copy on another device. If it opens without asking for the password, it is not protecting the contents.
Can I make a password-protected PDF from Pages?
Yes, for documents you write yourself. In Pages for iPhone, tap the menu button, tap Document Options, then Set Password. Apple says "Adding a password to a document encrypts the file" (Apple: password-protect a Pages document).
When you export that document, Apple says the password "applies to copies exported in PDF and Word formats" (Apple: export from Pages). There is no way to recover a forgotten Pages password.
How should I send the password?
Not in the same message as the PDF. Send the file by email and the password by text, or say it on a call. Anyone who gets both has everything.
What if I just want to keep PDFs private on my phone?
A password on each PDF is fiddly for things you only store. Tax returns, lease agreements and medical letters are easier in one encrypted place.
In Cryptile:
- Open a vault with your pattern.
- Tap Add → Files and pick the PDFs from the Files app.
- Delete the originals from Files once they are in the vault.
Each file is encrypted with AES-256-GCM before it is saved, and you can read it inside the app. With Cryptile Plus, text in PDFs is read on your device at import. You can then search for a name or reference number. You can also share a PDF into Cryptile from Mail or Safari with the share sheet.
To send a PDF from the vault, use Share / Save to Files. That hands over a decrypted copy, so lock it in Preview first if it is going to someone else.
What this doesn't protect against
A password is only as strong as its length. Anyone holding the file can try to guess a short one offline. Once a recipient opens the PDF, they can save, print or screenshot it. Copies already sent by email or synced to cloud storage stay where they are.
Do it with Cryptile
Cryptile keeps PDFs, photos and notes in vaults encrypted with a key made from your pattern on your device. There is no account and no server.
Cryptile is free for up to 2 vaults, 100 photos and 10 videos, with encrypted iCloud backup included. Plus adds search inside the vault and removes the limits for $19.99 a year (7-day free trial) or $39.99 once.