PDF security explained: owner vs. user passwords

The two PDF passwords

A password-protected PDF can have two distinct passwords, and they do different jobs:

• Open (user) password — required to open and view the file at all. Without it, you cannot read the document.
• Owner password — controls what you can do with the file once it’s open: whether you may print, copy text and graphics, edit, or add annotations and form fields.

A document is encrypted whenever a user or owner password (or any restriction) is applied. You’re only prompted for a password on opening, however, if the file has an open password. That’s why a PDF can open normally yet still block printing and copying.

What restrictions can an owner password set?

Typical owner-password restrictions include:

• preventing printing,
• blocking text and image selection (and therefore copying to the clipboard),
• prohibiting changes to the document or merging it with others,
• preventing users from filling form fields or adding digital signatures.

How to tell if a PDF is secured

In Adobe Acrobat or Reader, a small padlock icon at the bottom of the window indicates the file is secured. Hover over it to see which restrictions apply. You can also open File › Document Properties › Security for a detailed summary of the file’s restrictions.

Encryption levels

PDF encryption commonly uses one of these algorithms, all of which PDF Decrypter Pro supports:

• 40-bit RC4 — an older, legacy encryption level,
• 128-bit RC4 — a stronger, widely used level,
• AES — the modern Advanced Encryption Standard.

Removing restrictions — the legitimate case

If a PDF you own is locked by an owner password you set and then forgot — or if you need to print or edit a document you have the legal right to modify — you can remove those restrictions. That’s what PDF Decrypter Pro is for: it removes the owner-password permissions so the file behaves like a normal, unrestricted PDF.

It is not a password cracker. It does not brute-force an unknown open password, and it is not intended to access copyrighted material you do not have rights to. See our Terms of Use.

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