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Lockbox guide

Encrypt a PDF with a password

There are two ways to put a password on a PDF. A PDF password is built into the file, and any PDF reader asks for it. A locked box such as Lockbox wraps the PDF (and anything else with it) in AES-256 in your browser, with nothing uploaded.

Updated · 4 min read

Which kind you want

  • A password inside the PDF suits a document someone will open in Adobe Acrobat Reader, Preview or a browser: it simply asks for the password. Make one with the app the PDF came from (see below).
  • A Lockbox box suits sending: the PDF’s name and size are hidden too, several files can go together, and any change to the box is caught. The other person unlocks it on yuzool.com/lockbox, or with a self-opening file, and then has an ordinary PDF.

A password inside the PDF

  • Microsoft Word: File › Save As (or Save a Copy), choose PDF, then Options and tick Encrypt the document with a password.
  • LibreOffice (free): File › Export as PDF, then the Security tab and Set passwords.
  • Preview on a Mac: File › Export, then set a password to open the document (in recent versions of macOS it’s under Permissions; older ones show an Encrypt box).
What Yuzool’s PDF Tools doesPDF Tools merges, splits, compresses and signs PDFs on your device, but it doesn’t add PDF passwords. Use it to get the PDF ready, then lock it with Lockbox, or add a password in one of the apps above.

Lock a PDF with Lockbox

  1. Open Lockbox and drop the PDF on the page.
  2. Set a password, or tap Make one for me.
  3. Tap Lock, then Save, and send the box. Send the password another way.

When it’s unlocked, Lockbox shows the PDF in the page before you save it. If a PDF has things in it you mean to hide for good rather than lock, black them out first with Redact.

Questions

Can I add a password to a PDF on my phone?

Lockbox works in any phone browser: drop the PDF in and lock it. For a password inside the PDF itself, use a PDF app that offers it.

Will the PDF still open in Adobe Reader?

A PDF locked with Lockbox is unlocked first (on yuzool.com/lockbox or with a self-opening file), and then it’s the same PDF as before, for any reader.

Which is stronger?

Both can use AES-256. What matters most is the password: a long one, or five random words, is the real protection either way.

Does Yuzool see my PDF?

No. Lockbox locks and unlocks on your device; the PDF is never uploaded.

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