How to password-protect a PDF, and how to remove a password
Short answer: To protect a PDF, encrypt it with a password: without the password the contents cannot be read at all. Use AES-256 encryption, which every current PDF reader supports, and a long password shared separately from the file. Print and copy restrictions are honoured by readers but are not real security. To remove a password you know, unlock the PDF and save an unprotected copy.
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PDFs have two kinds of password
PDF protection comes in two parts that are easy to confuse:
| Open password | Permissions password | |
|---|---|---|
| Also called | User password | Owner password |
| What it does | Encrypts the document; nothing can be read without it | Asks readers to block printing, copying or editing |
| How strong | As strong as the password itself | Advisory — readers honour it, but it can be removed |
| Use it for | Confidential documents | Discouraging casual copying |
Only the open password protects anything. The permissions are a request that well-behaved software respects; the PDF format cannot enforce them.
How to password-protect a PDF
- Open Protect PDF and add your document.
- Type a password, then type it again. Use the eye icon to check it.
- Choose what people can do once it is open: everything, print only, or read only.
- Download the protected copy.
The document is encrypted with AES-256, the strongest encryption the PDF format offers and the one Acrobat itself uses. Adobe Reader, macOS Preview, the viewers built into Chrome, Edge and Firefox, and the readers on iPhone and Android all open it. Nothing about the pages changes: text stays selectable once opened and the file stays much the same size.
Choosing and sharing the password
- Long beats clever. Three or four unrelated words is stronger than a short string of symbols, and easier to type.
- Never send the password in the same email as the file. Use a text message, a phone call or a different app.
- Keep a copy somewhere safe. There is no way to recover a forgotten password — not for you, and not for us.
The password you enter is used once to encrypt the file and removed from our records as soon as the job finishes.
How to remove a password from a PDF
If a PDF asks for its password every time — a bank statement, a payslip — you can save a copy without it, as long as you know the password.
- Open Unlock PDF and add the document.
- Enter the password. If the PDF opens without one but blocks printing or copying, leave the field empty.
- Download the unlocked copy.
The tool tries the one password you give it, once. It does not guess, crack or recover passwords, and it should only be used on documents you have the right to unlock.
Changing a password
To change the password on a protected PDF, unlock it with the current password, then protect the unlocked copy with the new one. The same route works if you need to edit or sign a protected document: unlock, make the changes, protect again.