pdfpix

Protect a PDF with a password

or drop one here

Password protection

Require a password whenever this PDF is opened.

Uses PDF 1.7 AES-128. PDF/A files stay archival and are not encrypted.

Choose a PDF file first.

Add an open password to a PDF so it asks for one before it shows a page. The work happens in this browser tab. The password stays in the tab, never travels to a server, and never reaches analytics. The protected copy is opened again with that password to prove it works.

How to protect a PDF

  1. Choose a PDF

    Press Choose a PDF, or drop one on the page. The file stays in this browser tab.

  2. Leave Protect selected

    Protect is selected when this page opens. Use Unlock only when you want to remove protection using a password you know.

  3. Enter the new password

    Use at least six characters and enter the same password twice. The password stays in this tab and is excluded from analytics and diagnostics.

  4. Protect, check and download

    The output is opened again. Its pages, page sizes, selectable text and password requirement must pass before Download appears.

What an open password does, and what it does not

An open password is the one a reader asks for before it draws a page. Without it the file is encrypted bytes. That is the protection this page writes, and it is the only PDF password a viewer cannot choose to ignore.

The other kind is a permissions password, often called an owner password. It marks a file as no printing, no copying or no editing. Those flags are advice. Adobe Reader follows them, many other readers do not, and any tool that can open the file can clear them. pdfpix does not offer a control it cannot prove, so this page sets the open password and nothing else.

The encryption is standard AES-128 inside a PDF 1.7 file. That is what the browser library can write today. It is not AES-256, and this page says so instead of leaving you to guess. Six characters is the minimum it accepts. Only the first 32 characters reach the key, so a passphrase longer than that adds no strength.

Two kinds of file refuse a password. A PDF/A file forbids encryption, because an archive format has to open in fifty years without a key, so the original comes back unchanged. A PDF that already carries protection has to be unlocked first, with the password you hold, before a new one can go on.

One password for opening and owning

The password you enter becomes both the open password and the owner password. Every permission flag stays on, including high-resolution printing, copying, editing and form filling, so anyone who types the password gets the whole document.

Questions

Does the password ever leave this tab?
No. The PDF, password, protection and verification stay in this browser tab.
What protection does this add?
It writes a PDF 1.7 file with standard AES-128 open-password protection. It does not claim AES-256.
Why will it not protect a PDF/A file?
PDF/A forbids encryption. Adding a password would break the archival format, so the original stays unchanged.
Can I remove protection here too?
Yes. Choose Unlock, or open the focused Unlock page, and enter a password you know. The tool does not guess or crack passwords.
What does the protect check cover?
It opens the output again, compares its pages, page sizes and selectable text with the source, then confirms that the new password is required. A failed output is not offered for download.
Can I stop people printing or copying instead?
Not here. This tool sets the open password, the one a reader must type before any page appears. Permission flags are honoured by some viewers and ignored by others, so pdfpix does not offer a control it cannot prove.
Which characters can the password use?
Letters, digits and symbols from the Latin-1 set, which includes accented letters such as é and ß. A character outside that set, such as an emoji or a Chinese character, stops the run with an error, and your original file is not changed.
What if I forget the password?
The protected copy stays locked. pdfpix keeps no copy of the password, and Unlock asks for the password before it opens the file. Store the password before you send the protected copy, which is named after your file with -protected.pdf at the end.

Related tools

Each runs in a browser tab like this one, reads its own output back before the download, and needs no account. The footer links every tool.

Where to go next