How to Encrypt Documents and PDFs You Keep on Your iPhone

Quick answer

You can encrypt documents and PDFs on your iPhone without installing anything. Preview can lock a PDF with a password, and Pages, Numbers, and Keynote can password-protect their own files. Both actually encrypt the file, using AES-256 — the same NIST-standardized cipher used across hard drives, cloud storage, and password managers. What neither one does is protect everything sitting loose in Files, or give you one place to keep IDs, statements, and scanned records alongside the rest of your private content.

Step-by-step

Lock a PDF in Preview. Open the PDF in Preview, tap the menu next to the filename, then tap Lock. Turn on Require Password and enter the same password in the Password and Verify fields. Want to keep an unlocked copy too? Tap Duplicate first — locking creates a password-protected version of the file you were viewing.

Password-protect a Pages, Numbers, or Keynote document. Open the file, tap More, then Document Options, then Set Password. Enter and confirm your password and tap Done. Adding a password to a document encrypts the file — it's not just an app-level lock screen. Face ID or Touch ID can unlock it afterward so you're not retyping a password every time; manage which apps get that biometric shortcut under Settings > Face ID & Passcode > Other Apps. For a deeper look at when biometrics are the right tradeoff and when a passcode wins out, see why a passcode still beats Face ID for real privacy.

One thing to know before you set a password: there's no recovery if you forget it, and each document only holds one password at a time — changing it replaces the old one for anyone else you'd shared it with.

Both methods protect the file itself, which matters more than it sounds like. A locked PDF or Pages document stays encrypted if you AirDrop it, attach it to an email, or move it to another cloud drive — the password requirement travels with the file, not just with the app you opened it in. Compare that to a folder that's merely hidden from the Files app's main view but opens freely once someone finds it.

Common problems and fixes

"I locked my files, but they still sync to iCloud — is that a gap?" By default, iCloud Drive protects your data, but full end-to-end encryption of Drive documents and PDFs is only guaranteed once you turn on Advanced Data Protection. With it on, your trusted devices hold the only keys to the extended set of protected categories — not even Apple can read the contents, including in the event of a server-side breach. One honest exception: if you're actively co-editing a shared document in real time, the keys for that session are mediated through Apple's servers so collaborators can sync changes. That's a documented tradeoff of live collaboration, not a flaw in the feature.

"My phone was lost or stolen — are my locked files safe?" A document password matters more once someone actually has your phone in hand. Start with the protections that stop them from getting that far in the first place — see what Stolen Device Protection covers and what it doesn't for the layer that sits in front of any file-level password.

"I forgot my document password." There's no way around this one — Apple can't reset it for you. The practical fix is saving it in a password manager the moment you set it, same as you'd handle any other credential you can't afford to lose, and picking something you'll actually remember rather than a one-off you'll never type again.

Doing this with Privara

Locking individual PDFs and Pages files works, but it's one password per file, scattered across whatever folder each document happens to live in — and it does nothing for the photos, videos, and contacts you'd also rather keep private. Privara gives you one AES-256-encrypted vault for all of it — documents, photos, videos, and contacts together — hidden behind what looks and works like an ordinary calculator. There's no account to create and nothing uploaded anywhere by default, so it stays a private, zero-knowledge vault on your device, not one more login tied to a company server. Enter your PIN into the calculator and the vault opens; enter the wrong one and it stays a calculator. For the documents, IDs, and records you don't want left exposed in Files, that single vault beats locking each one on its own. Get Privara on the App Store to set it up in a few minutes.