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Protect PDF

Protect your PDF files with a password

Password protect a PDF so that it asks for the password you choose before it opens. The tool applies AES-256 encryption: the password is required to open the file. Type the password twice, press Protect and download, and an encrypted copy named with _protected downloads, for example budget_protected.pdf.

Encryption happens on the ProPDF server: the file and the password are sent over HTTPS to AWS in the Paris region (eu-west-3), the file is processed, then deleted as soon as the task ends, and the password serves only for the encryption, without being logged. The size limit is 4 MB per file.

How to password protect a PDF

  1. Open your PDF Drop the PDF you want to lock, or click the upload area to find it on your device. Its page count and size appear at the top of the panel.

  2. Choose a password Type it in the Password field. A Weak, Medium or Strong label rates it as you type, and the eye icon shows or hides the characters.

  3. Confirm it Type the same password in Confirm password. If the two differ, Passwords do not match appears and the button stays disabled.

  4. Protect and download Press Protect and download. The encrypted copy downloads with _protected added to its name.

  5. Test the copy Open the downloaded file: your PDF reader should ask for the password before it shows any page.

What the protection covers

AES-256 encrypts the text, images and properties of the file, and its pages cannot be displayed until the right password is typed. Without the password, a reader shows a password prompt instead of the content.

The tool sets a single password for everything: there is no separate owner password and no permission option. Printing is allowed for anyone who opens the file with the password.

Think of it as a lock on the door, not a rule for the people you let in. Do not count on it to stop someone who has the password from copying or editing the content.

Picking a password that holds up

The strength label is a guide and never blocks you. Strong means at least 12 characters including a symbol, and a space or an accented letter counts as one; Medium, at least 8 characters with both a letter from A to Z and a digit; anything shorter or simpler is rated Weak.

Encryption is only as good as the password behind it. A passphrase of four or five unrelated words is easier to remember than a short jumble of characters, and harder to guess.

Send the password by another route than the file: if the PDF goes by email, share the password by phone or text message.

Sharing and updating a protected file

  • Very old PDF readers may not open AES-256 files. If a recipient cannot open the copy, suggest a current reader.
  • To change the password, open the file in Unlock with the current one, then protect the unlocked copy with the new password.
  • A PDF that already asks for a password cannot be protected again directly: unlock it first.
  • Keep an unprotected original in a safe place if losing the password would be a problem.

Features

  • AES-256 encryption with the password you choose
  • Password required to open the file
  • Confirmation field to catch typing mistakes
  • Eye icon to show or hide each field
  • Weak, Medium or Strong rating as you type
  • Printing kept available for people who have the password
  • Encrypted copy named with _protected, original left as it is

Why Use This Tool

  • Email a payslip, a contract or a tax form that only people with the password can open
  • Add a lock to sensitive PDFs kept in shared folders or on a laptop
  • Lock a scanned ID card or a signed form before you store it in a cloud folder
  • Protect the output of Compress, Sign or Edit straight from the panel those tools show after a download

Frequently Asked Questions

What encryption does the tool use?

AES-256. The password you set is required to open the file.

Can I restrict printing, copying or editing?

No. There are no permission settings, and printing stays allowed. The tool controls who can open the file.

What if I forget the password?

ProPDF does not store it and has no way to retrieve it. The Unlock tool needs the password as well, so without it the protected copy stays closed.

Can I change the password of a protected PDF?

Yes, in two steps: remove the current password with Unlock, then protect the unlocked copy again with the new one.

Will the recipient need special software?

No, a PDF reader is enough, together with the password. Very old readers may not support AES-256.

What happens to my file and password on the server?

The file is processed on our server, then deleted as soon as the task ends. The password is used to encrypt it and is not logged.

Why does a weak password still work?

The rating only informs you. Any password is accepted as long as both fields match and are not empty, so the choice stays yours.

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