Protect PDF
Put a password on a PDF so nobody can open it without one. AES-256 encryption, done on your own computer. Nothing is uploaded.
Drop your PDF here
They stay on your computer. Nothing is sent to a server.
How to protect a PDF
Uploading a file to put a password on it defeats the point: for a moment, somebody else had the unlocked copy. Here the encryption happens inside your browser, so the only unlocked copy is the one you already had.
- Drop the PDF here.
- Type the password twice.
- If you want, also stop printing, copying or changes.
- Press Protect it, and keep the password somewhere safe.
How strong is it
The file is encrypted with AES-256, the strongest encryption a PDF can carry, and every modern reader can open it. With a good password the file cannot be read without it.
The weak point is the password itself. A short word can be guessed by a computer trying millions a second. Eight characters or more, or three or four ordinary words strung together, is far safer.
What the stops on printing and copying really do
They are a request written into the file. Acrobat, Preview and most readers respect it; some programs do not, and nothing can force them to. Treat the stops as a polite sign on the door and the password as the lock.
Good to know
- I forgot the password. Can you get the file back?
- No. Nobody can - the password never leaves your computer, and that is exactly what makes it safe. Keep a copy of the unprotected file if you might need it.
- Will it open on a phone?
- Yes. Every current reader on phones and computers opens AES-256 PDFs and asks for the password.
- Can I change the password later?
- Unlock it with Unlock PDF, using the old password, then protect it again with the new one.
- Is anything uploaded?
- No. The file is encrypted in your browser and saved straight back to your computer.