How to use it
- Press Choose files or drop one or more PDFs. Each one will be encrypted with the same password.
- Type the password in Password to open the PDF and again in Type it again. Tick Show the password if you want to check it. The files start as soon as both fields match.
- If you also want to discourage printing, copying or editing, tick the boxes under Also ask PDF readers to block (optional) before you type the password.
- Press Download for each file, or Download all for one ZIP. Open one of them to check that it asks for the password.
What the password does
The tool encrypts the PDF with a 256-bit key. The QPDF manual notes that 256-bit encryption always uses AES, and that this method (revision 6) is the only one not deprecated in PDF 2.0. Without the password, a PDF reader can't show the pages: the content in the file is scrambled, not just hidden behind a prompt.
Every PDF reader in common use asks for the password when you open the file. There is no back door: if you forget the password, this site can't recover it, because it never saw or stored it. Keep it somewhere safe before you delete the unprotected original.
Restrictions are a request, not a lock
The optional boxes add the PDF's built-in permission flags for printing, copying and editing. They are set with a second, random password that nobody is told, so they apply even to people who know your open password.
Be clear about what they are. The QPDF manual says the security of these restrictions "is solely enforced by the software": a reader that follows the PDF standard honours them, and one that doesn't can ignore them. Use them to discourage casual copying or printing, not to protect a secret. That is also why our Unlock PDF tool can remove them from a file you can already open.
Choosing a password
- Longer beats clever: four or five unrelated words are easier to remember and harder to guess than a short word with symbols.
- Send the password through a different channel from the file, for example the file by e-mail and the password by phone or text message.
- Don't reuse a password from an account. Anyone you send the file to will know it.
What happens to your file
Your browser reads the PDF, QPDF (an open-source PDF library compiled to WebAssembly) encrypts it in a background worker, and the new file is offered as a download. The password stays in that tab's memory and is gone when you close it. The original file on your device is not changed.
Questions
- Can someone open the PDF without the password?
- Not with a normal PDF reader. The pages are encrypted with AES-256 and need the password to decrypt. A weak password can still be guessed by trying many candidates, so pick a long one.
- I forgot the password. Can you unlock it?
- No. The password was never sent to us, and there is no master key. That's the point of the encryption. Keep a copy of the original or the password in a safe place.
- Will the restrictions stop people printing or copying?
- Only in readers that respect them. The PDF format leaves enforcement to the reading software, so treat the restrictions as a polite request. Only the open password keeps people out.
- What if the PDF already has restrictions?
- If it opens without a password, the old restrictions are removed and the file is protected with your settings. If it already needs a password to open, remove that first with Unlock PDF.
- Is my PDF uploaded?
- No. The encryption runs in your browser. You can check it: the privacy receipt under the result shows the network requests made while processing, and bytes sent stays at 0.