On your device
How to password protect a PDF on iPhone
By DeckleUpdated
To password protect a PDF on iPhone, open Password protect PDF in Safari, tap Select a file and choose the PDF, type a password of at least 6 characters in Password and Confirm password, then tap Protect this PDF. Deckle saves an AES-256 encrypted copy that asks for the password every time it is opened. Your original stays unprotected. On iOS 26 and later, the Preview app can lock a PDF too; see below.
How to password protect a PDF on iPhone with Deckle
- Open Password protect PDF in Safari, or another browser.
- Tap Select a file and choose the PDF from the Files app.
- Type a password in Password. It must be at least 6 characters.
- Type it again in Confirm password. A mismatch is shown under the field.
- Tap Protect this PDF. The button stays disabled until both fields match.
- Download the protected copy, which has "(protected)" added to its name.
- Open it from the Files app to confirm it asks for the password.
Before the result appears, Deckle checks that the new file refuses an empty password and opens with yours.
What the password does
The password is needed to open the PDF in any reader, on any device. Deckle uses AES-256, the strongest encryption the PDF standard defines. It sets one open password and does not add separate printing or editing restrictions.
A forgotten password can't be recovered. Save it in the Passwords app or another password manager before you delete the unprotected original.
When you send the file, share the password a different way: email the PDF and text the password, or say it on a call. One intercepted message then can't open the document. See how to share a password-protected PDF.
Lock a PDF with Preview on iPhone
Apple's page Lock PDFs in Preview on iPhone describes it, for iOS 26 and later:
- Open the PDF in the Preview app. To keep an unlocked copy, tap Duplicate first, as Apple's page advises.
- Tap the button next to the file name, then tap Lock.
- Enter the same password in Password and Verify. Require Password turns on automatically.
- Tap the button to apply it.
Apple describes this as locking the PDF to prevent others from editing or deleting your work. Preview locks the file you opened unless you duplicate it first.
Pages documents
If the document starts in Pages, Apple explains in Convert to Word, PDF, or another file format in Pages on iPhone that a password set on the Pages document applies to copies exported in PDF and Word formats. Set the password on the document, then export it as a PDF.
Tips
- Use a passphrase. Three or four unrelated words are easy to type on a phone and hard to guess.
- Don't reuse your Apple Account password. You will share this one.
- Merge first, protect last. A protected PDF can't be merged. Combine the files in Merge PDFs, then protect the result. See how to merge PDF files on iPhone and iPad.
- Don't protect files for upload forms. Most portals can't open them.
Frequently asked questions
How do I put a password on a PDF on my iPhone?
Open Password protect PDF in Safari, set the password and tap Protect this PDF. On iOS 26 or later you can also use Lock in the Preview app.
Is my password sent anywhere?
No. The PDF is encrypted in Safari on your iPhone, and the password is not stored or uploaded.
How do I remove the password later?
Open the protected PDF in Unlock PDF, enter the password and tap Remove the password.
Can someone open it on Windows or Android?
Yes, with the password. AES-256 is part of the PDF standard, so any current PDF reader asks for it.
What if I forget the password?
The PDF can't be opened without it, and Deckle keeps no copy. Keep the unprotected original until the password is saved, then delete the original if it shouldn't be kept.
Can I protect several PDFs at once?
No. Protect each file in turn, or merge them first and protect the combined file.
Related tools
- Password protect PDF to add an open password
- Unlock PDF to remove a password you know
- Merge PDFs to combine files before protecting them