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Password Protect PDF

Lock a PDF with AES-256, and say what a reader may print, copy or change. Free, and runs entirely in your browser — nothing is uploaded.

About PDF Password & Permissions

Encrypts a PDF and states what may be done with it: whether it can be opened without a password, and whether a reader may print it, copy text out of it, change it or comment on it. The document is rewritten with AES-256 under revision 6 of the standard security handler — the encryption current PDF readers expect — and everything happens in this tab, which is the point: a password typed into a website is a password that website has seen.

Locking a document and restricting one are the same operation, which is why they are one tool. In a PDF, permissions only exist *inside* encryption: the flags live in the encryption dictionary and are held in place by the owner password. There is no way to say "this may not be printed" without encrypting the file, so a password tool and a permissions tool would always be two doors into the same room — and whichever one you opened would be missing half the switches.

A PDF distinguishes two passwords, and either alone is enough here. The open password is asked for before the document will display at all; leave it empty and the file opens freely while still carrying its restrictions, which is the usual arrangement for a circulated document. The owner password is never asked for on opening — it is what lets somebody lift the restrictions later. Set both for a document that is genuinely confidential *and* marked read-only; if the owner password is left blank, everyone who can open the file also holds owner rights, and the restrictions become advisory only.

Be clear about what restrictions are. They are honoured by the reader rather than enforced by mathematics: the content is decrypted the moment the document opens, so a reader that chooses to ignore the flags can, and several do. Treat them as a clearly stated intention. Anything that must not be copied must not be sent; what this offers is a document that says what it expects, and a password that stops a casual reader changing that.

Where it helps

  • AES-256 encryption, generated with the browser's own cryptographic random source.
  • The document and both passwords stay in this tab.
  • Every permission a PDF actually defines, set in one pass — printing, high-resolution printing, copying, editing and commenting.
  • Either password alone works: lock the file, or leave it freely readable while stating its terms.
  • Screen-reader access is never denied, whatever else is restricted.
  • Reports exactly what a reader will be allowed and refused.
  • The output is an ordinary PDF that any current reader will ask a password for.

Limits

  • Permissions are honoured by the reader, not enforced by the encryption; the content is decrypted once the file opens, and free tools that ignore the flags exist.
  • Anyone with the owner password can lift every restriction, and so can any tool given it.
  • Without an open password the content is encrypted under a key everyone has, so it protects nothing confidential.
  • A file that is already password protected must have its existing password removed first.
  • Any digital signature the document carried stops validating, because the file is rewritten.
  • There is no recovery: a password nobody remembers means a document nobody can open.

Frequently asked questions

How strong is the protection?

The encryption is AES-256 and the key comes from your password, so the password is the weak point. A short or reused one is guessable however good the cipher is.

Where did Change Permissions go?

Here. It was the same operation under a second name — permissions in a PDF only exist inside encryption, so setting them always encrypted the file, and this tool always wrote permissions. Keeping them apart meant the password tool could not set the print-resolution flag and the permissions tool looked as though it would not lock a document. Its old link now opens this page.

Can somebody just ignore the restrictions?

Yes. They are flags a reader agrees to honour, and the decryption key is in the file for anyone who can open it. Every serious PDF library can strip them. They stop casual copying and state your intent; they are not a security control.

Why is accessibility always allowed?

Because the flag that denies it only blocks screen readers, which is hostile and, in many jurisdictions, unlawful. Nothing is gained by setting it: a reader determined to extract text ignores the flags anyway.

What does the owner password do?

It lifts the restrictions. Set one that differs from the open password if the printing and copying switches are meant to hold for the people you send the file to. Leave the open password empty instead, and you get a document anyone can read but that is marked read-only.

Can someone remove the restrictions without the password?

Yes, if they can open the file: restrictions are a reader convention. Only the open password actually keeps content unreadable.

It refused a file that is already protected — why?

Re-encrypting an encrypted file needs its current password first. Remove it with PDF Password Remover, then protect the result.

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