How PDF passwords actually work
When you password-protect a PDF, the PDF's internal streams are encrypted with a key derived from your password. Any viewer that opens the file — Acrobat, Preview, Edge, a Kindle, an iPhone — will prompt for the password before rendering a single page. There's no special "Unfuss reader" required; the password travels with the file.
PDF supports two passwords at once:
- User password — the one your recipient types to open the document at all. Without it, the file is unreadable.
- Owner password — an optional second password you keep for yourself. It controls permissions: whether the recipient can print, copy text, edit the file, or fill in forms. If you set an owner password and restrict (say) printing, the recipient can open the PDF but the Print menu will be greyed out — unless they enter the owner password.
How strong is PDF encryption?
Modern PDF readers use AES-256 encryption by default, which is military-grade. But here's the catch: the cipher is only as strong as the password that unlocks it. A four-character password can be brute-forced on a laptop in seconds; a twelve-character random one would outlive the sun. The algorithm doesn't matter if the key is weak.
How to pick a password that actually protects the file
- Length matters most. Twelve characters is a reasonable floor; sixteen is better.
- Avoid common patterns. "Password123!" is not strong just because it has four character types — it's on every leaked-password list.
- Passphrases work. Four random unrelated words (correct-horse-battery-staple) are easier to remember and harder to break than a shorter mixed-character string.
- Use a password manager. If you have one, generate a 20-character random password and store it there. Send it to the recipient through a different channel than the PDF itself.
Frequently asked
Is my PDF uploaded?
No. The PDF bytes are read into your browser tab, encrypted in memory with pdf-lib, and saved back as a new file. No part of your document or your password is transmitted anywhere.
What if I forget the password?
Nothing can be done. The encryption is one-way in a useful sense — without the password the document is unrecoverable. Unfuss has no reset mechanism because Unfuss never saw the password. Always keep a backup of the original, unprotected file.
Will every PDF viewer prompt for the password?
Yes. Password-protection is part of the PDF specification, not a Unfuss feature. Acrobat, Preview on Mac, Edge, Chrome's built-in viewer, Okular, and every serious mobile reader all support it.
Can I password-protect a PDF that's already signed?
Technically yes, but the signature will be invalidated because encrypting the file changes its bytes. Sign first, protect second, and communicate to your recipient that the signature is visual only if you used Unfuss Sign.
Can I remove a password from a PDF I received?
Not with this tool yet — decrypting an encrypted PDF requires the password and a slightly different code path. If you have the password, you can open it in Preview (Mac) or Acrobat and re-save without protection, then process it here.
How does XML password protection work?
XML is plain text — the format itself has no built-in password mechanism. Unfuss wraps your XML file inside an AES-256 encrypted ZIP archive. The recipient opens the ZIP with the password (in Finder, Explorer, 7-Zip, The Unarchiver, or any standard tool) and the original XML is extracted unchanged. This is the most portable option: no special software required on the receiving end.
Can the XML be opened directly without unzipping?
No. To protect XML, the bytes have to be encrypted, which means the output isn't a valid XML file anymore — it's a ZIP. The recipient unzips it (one click on every modern OS) and gets the original XML. If you need a workflow that keeps the file as XML, that requires W3C XML Encryption (xmlenc), which most consumer tools can't read; Unfuss doesn't offer that mode.
Why isn't DOCX supported?
Microsoft's Office format uses an encryption scheme (ECMA-376 Agile Encryption) that doesn't have a mature JavaScript implementation. Building one would be a significant project. For now, export your Word document as a PDF (File → Save As → PDF) and protect the PDF with this tool — the result opens anywhere and requires the password just the same.