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About

Unlock & Protect PDF

Drop a PDF to take its password off, if you know it, or to put one on. A locked file is opened with its password and saved without it; an open one is saved with AES-256 and the printing, copying and editing you allow. Every copy is opened again by a second PDF reader before it is saved.

What it does

  • Opens every lock a PDF password still makes: RC4 at 40 and 128 bits, AES-128 and both forms of AES-256.
  • Takes off restrictions on a file that opens without a password, such as no printing or no copying, without asking for one.
  • Tries a password that opened one file on the others, since a bank locks a year of statements with the same one.
  • Puts on AES-256 with a password to open, the permissions you choose, or both; an old password is changed in the same step.
  • Keeps bookmarks, form fields, attachments and the document’s details: the file is decrypted, not rebuilt page by page.
  • Checks every copy in pdf.js, Firefox’s reader: it must open with the new password alone and allow exactly what you chose.
  • Warns when a file is digitally signed, since writing it again breaks the signature, and when a PDF/A file stops claiming to be one.

How to use it

  1. Choose Remove password or Add password.
  2. Drop one or more PDFs on the window.
  3. Type the password of any file that asks for it.
  4. To protect, type the new password and choose what readers may do.
  5. Download the file, or a zip of them all.

What it does not do

  • Recovering a forgotten password: the tool decrypts with the password you give it and never guesses, which against AES would take longer than anyone has.
  • A file locked with a certificate instead of a password: only the private key it was sent to opens it, and that key never leaves its owner.
  • Keeping a digital signature: adding or removing a lock rewrites the file, and a signature covers the exact bytes it signed.
  • Enforcing permissions: they are a request that Acrobat and browsers honour, and any program that ignores them can copy an open file.

Questions

Can it unlock a PDF without the password?

Only a file that opens without one and just restricts printing or copying: those restrictions come off. A file that asks for a password to open is encrypted with it, and without it there is nothing to decrypt with. The tool never guesses passwords.

Is it safe to type a bank statement’s password here?

The file and its password stay in your browser: nothing is uploaded, and neither is stored. Close the window and both are gone.

Will people still be able to print or copy it?

That is what the permissions decide, and Acrobat, Chrome and Preview honour them. They are not encryption, though: anyone who can open the file can find a program that ignores them. For a file nobody else should read, give it a password to open.

Which readers open the protected file?

Every current one: Acrobat Reader since version X (2010), Chrome, Edge, Firefox, Safari and Preview. The file is AES-256, the cipher the PDF 2.0 standard recommends; RC4 is not offered, since it is broken.

Everything here runs in your browser. Nothing you type, paste or open is uploaded, and there is no account and no queue. How that works.

Often used with

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  • PDF Page Numbers: Number the pages of a PDF: any corner, any first page, Roman numerals or Bates numbers across files, each copy read back by a second reader.

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