Password protect a PDF
To add a password to a PDF, drop in the file, type the password twice, and download an encrypted copy. The encryption happens in this tab, so neither the document nor the password goes anywhere.
Keep the password somewhere safe. Nobody can open the file without it, and there is no way to recover it.
How to use it#
- Drop the PDF onto the box above, or click it to choose one.
- Type the password it should ask for, then type it again to confirm it.
- Press Protect the PDF.
- Download the protected copy. The original is left as it was, without a password.
A forgotten password cannot be recovered#
The password is what the encryption is built from, and it is not kept anywhere, in the file, on this site, or with anyone else. If it is forgotten, nobody can open the protected copy, including you, and nothing here or anywhere else can get it back.
That is why it is typed twice, and why the original is left unprotected. Keep the original until you have opened the protected copy with the password and seen it work, and put the password somewhere safe, such as a password manager, before you send the file on.
What the protection does#
The file is encrypted with AES-256, the strongest method the PDF format offers. Current readers open it: Acrobat, Preview on a Mac, the viewers built into Chrome, Edge, Firefox, and Safari, and the PDF apps on phones. The pages themselves are scrambled, so without the password there is nothing in the file to read.
The weak point is the password, not the encryption. A short password or a common word can be found by a program that tries millions of guesses, because a copy of the file can be attacked at leisure. A password of a few unrelated words is long enough that trying them all is out of reach.
What it does not do#
It does not set permissions. PDFs can also carry flags asking readers not to allow printing or copying, but those are only requests, easily ignored, and anyone who has the password to open the file can do everything with it. This tool adds the one kind of protection that holds: nobody reads the document without the password. To add those flags as well, under an owner password of their own, use the PDF restriction tool.
Nothing else in the document changes. Text stays selectable, links still work, and the pages look exactly as they did. To take the password off again later, use the PDF password remover with the same password.
Frequently asked questions#
Is my PDF or my password uploaded?
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Neither. The encryption runs in this tab, using code fetched the first time you press the button. The password never leaves the form field, and the protected file is handed straight back to you.
What if I forget the password?
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Then the protected copy cannot be opened, by you or anyone else. The password is not stored anywhere, and there is no recovery. Keep the unprotected original until you have checked the new copy opens, and store the password somewhere safe.
How strong is the encryption?
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AES-256, the strongest the PDF format has. How safe the file is depends on the password: a short or common one can be guessed by a program that tries millions, so use a long one, such as a few unrelated words.
Will the person I send it to be able to open it?
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Yes, with the password, in current PDF readers: Acrobat, Preview on a Mac, the viewers in Chrome, Edge, Firefox, and Safari, and phone apps. Send the password separately from the file, for example by text message rather than in the same email.
How do I send a password protected PDF by email?
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Protect it here, attach the protected copy as you would any file, and send the password another way, such as a text message or a phone call. Anyone who gets the email alone then has a file they cannot open. The protected copy is the same size as the original, give or take a few kilobytes, so it fits wherever the original did.
Can I stop people printing or copying the document?
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Not with this tool, but the PDF restriction tool adds those limits under an owner password, with an optional password to open the file too. Be aware that restrictions are flags readers are asked to respect, and some readers ignore them. A password needed to open the file is the protection that holds, because without it the pages cannot be read at all.
Can I change the password on a file that already has one?
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Yes, in two steps. Remove the current password with the PDF password remover, which needs the password you have now, then protect the unlocked copy here with the new one.