How to password-protect a PDF on iPhone
On iPhone with iOS 26, Apple’s Preview app can require a password to open a PDF. Check which copy you lock: a duplicate you leave unprotected remains readable without that password.
Quick answer: Open the PDF in Preview, tap the Actions menu beside its filename, choose Lock, turn on Require Password, enter and verify a password, then tap Done. If you want to keep a separate copy without a password, duplicate the PDF before locking one copy.
Lock a copy in Preview
- Open the PDF in the Preview app on an iPhone running iOS 26.
- If you need both protected and unprotected versions, first tap the Actions menu beside the filename and choose Duplicate. Be deliberate about where each copy is saved.
- On the copy you want to protect, tap the Actions menu beside the filename, then tap Lock.
- Turn on Require Password. Enter the same password in both fields and tap Done.
- Close and reopen the locked PDF to check that it asks for the password. Keep the password somewhere private and separate from the file.
Apple’s instructions for locking PDFs in Preview note that you can duplicate a document first to keep a version that is not password-protected.
Check for other copies
Password-locking one PDF does not lock every copy of the document. Before sharing or deleting anything, check the original location and any duplicate in Files, Downloads, email, a message, or cloud storage. Avoid attaching the unprotected copy by mistake. If the document is sensitive, choose a unique password that you can retrieve safely.
Apple’s Files guide explains that Files can copy, move, share, or delete a selected file. Those actions apply to that file and location; they do not find every other copy.
A PDF password and a vault are different
A PDF password protects that document file. Ego’s current implementation instead imports a separate copy into a device-encrypted vault; import does not remove the source. Do not assume that an imported password-protected PDF will open in every app, or that keeping a vault copy changes the protection on an exported PDF.
Ego is in development for iPhone, and there is no public App Store download yet. If you are considering it for a locked PDF, check that the current app build can import and open that file before moving or deleting any other copy. See what importing a file does to its original and Ego’s current features and limits.