How to remove a password from a PDF you own

Two passwords, two completely different situations

The open password (also called the user password)

This is real encryption. The contents of the file are genuinely scrambled, and the password is what unscrambles them. Without it, there is no document to read — not a locked document, no document.

Modern PDFs use AES, which is the same class of encryption used to protect everything else on the internet. If you know the password, removing it is a single operation: open the file, supply the password, save without one. If you do not know it, the honest answer is that you are not getting in, and you should go back to whoever sent the file. Anything online promising to “unlock” such a file is either guessing common passwords or taking your money.

The permissions password (also called the owner password)

This is a different thing wearing the same word. The file is not protected from you at all — it opens without asking for anything. What it carries is a set of flags saying “do not allow printing”, “do not allow copying”, “do not allow editing”, and a password that can change those flags.

Software that follows the specification honours those flags, which is why your reader greys out the tools. But the document itself is readable, the restrictions are a request rather than a lock, and essentially any PDF library can ignore them. They stop honest software, not determined people. This is worth understanding both ways round: if you have been relying on permissions to keep a document from being copied, it was never doing that.

Removing a permissions password

If it is your own document, or you have been given it to work on, the usual routes are:

• A desktop PDF editor with a security or permissions dialog. Open the file, clear the restrictions, save. Emifyn PDF Studio does this; so do most editors.
• QPDF, a free command-line tool, with qpdf --decrypt in.pdf out.pdf. It is small, open source, and the same library several PDF programs use underneath.
• Print to PDF. Crude, but it works and needs nothing installed: print the document to Microsoft Print to PDF. You get an unrestricted file at the cost of bookmarks, links, form fields and often text quality. Fine for a document you just need to annotate; poor for one you need to keep working on.

Removing an open password you know

1. Open the document and enter the password. This is the part nothing can skip.

2. Find the security settings. Usually under document properties or a security menu.

3. Set the encryption to none, or choose “save a copy without password”, depending on the program.

4. Save as a new file. Keep the encrypted original until you have confirmed the new one opens without prompting. There is no undo for this.

Things worth knowing

• Removing the password removes the protection. Obvious when written down, less obvious at four in the afternoon when the unprotected copy goes into a shared folder. Decide where the decrypted file is going to live before you make it.
• Some documents carry both passwords. You will need the open one to read it and the owner one to change the restrictions cleanly.
• Old encryption is weak encryption. Documents using 40-bit RC4, the original scheme, are not meaningfully protected by modern standards. If you are protecting something that matters, make sure your tool is writing AES-256.
• A signed document will lose its signature. Changing the encryption changes the file, which is exactly what a signature exists to detect.
• Upload thinking. The browser-based “unlock PDF” services work, but you are handing a document you considered worth protecting to a third party. That may be fine. Make it a decision.

If it is not your document

A restriction is usually there for a reason, even a mild one. If you have hit a permissions password on something a colleague or a supplier sent you, the fastest and least awkward route is almost always to ask them for an unrestricted copy — they can usually produce one in a minute, and it saves any question about whether you should have done it yourself. Where a document is protected under a legal or contractual obligation, that obligation does not stop applying because the file format is easy to work around.