Access and forms

PDF password protector

Put an AES password on a PDF, or take one off a file whose password you already know. The text stays selectable either way.

How this is calculated

The file is encrypted by QPDF running as WebAssembly in this tab: AES-256 with the PDF 2.0 revision, or AES-128 / RC4-128 for older readers. Decryption uses the same engine with the password you supply. Page content is not redrawn, so text, images and layout are unchanged.

There is no recovery. A PDF encrypted with a password nobody holds cannot be opened by this site, by us or by anyone else. Write the password down before you close this tab.
Print and copy permissions are requests to a reader, not locks. A reader that ignores them can still print. Only the open password actually keeps the content closed.
40-bit RC4 is offered only for very old readers and is not strong encryption. Choose 256-bit AES unless a specific old device forces otherwise.
The passwords you type stay in this tab. They are not uploaded, not logged and not written into the output file name.

Put an AES password on a PDF, or take one off a file whose password you already know. The encryption is done by QPDF compiled to WebAssembly and running in this tab, and the text stays selectable either way.

What the password actually does

With a password added the page content is encrypted. A reader without the key shows nothing, and no tool on this site — or anywhere else — can open the file without the password. The passwords themselves never leave the tab, are not logged and are not written into the file name.

There is no recovery. Lose the password and the file is gone, so write it down before closing the tab. A file that already has a password can be opened here only if you supply it, which is why this page is also where an existing one is removed.

Permissions are requests, not locks

The printing option writes a permission into the file. A reader that honours it refuses or degrades printing; a reader that ignores it prints anyway. Only the open password keeps content closed, and only encryption makes that true.

256-bit AES is the default because it is what current readers support. 128-bit AES is there for an older viewer that chokes on AES-256, and 40-bit RC4 exists only for very old equipment and is not strong encryption. Where a device forces the weakest option, treat the file as lightly protected.

Questions readers ask

I forgot the password. Can you crack it?

No. There is no back door, no recovery key and no server copy of the file. That is the point of the feature.

Will the result open in every reader?

AES-256 needs a reader from roughly the last fifteen years. Test on the device that must open it before you delete the unprotected original.

Why is the output a different size?

Encryption adds a dictionary and rewrites the file structure. Page content is not redrawn, so nothing looks different once the file is opened with the password.

Tools

PDF password protector