Protect PDF
Add password protection to your PDF files. Set a password and control printing and copying permissions. Secure your documents in seconds.
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Max file size: 50MB
What Password Protection Actually Does
Modern PDFs support AES-256 encryption, the same standard used for online banking and disk encryption. When you password-protect a PDF, the file's content is genuinely scrambled; without the password, no PDF reader can show the text or images. This is real cryptographic protection, not a lock that says 'please do not enter'. The PDF specification (ISO 32000-1) defines two types of password: a user password (needed to open the file) and an owner password (needed to change permissions like printing or copying).
The tool above sets an owner password and applies the permission flags you choose. You can allow or block printing and copying. Anyone opening the file in a normal reader will see the document, but actions you have blocked will be greyed out. To require a password just to open the file, you would need a tool that sets the user password instead.
Choosing a Password That Will Survive
PDF passwords are brute-forceable, even AES-256 ones, if the password itself is weak. A four-character password can be cracked in seconds; a six-character one in minutes. Use at least twelve characters with a mix of letters, numbers, and punctuation, or a passphrase of four random words. Avoid dictionary words alone, names, dates, or anything you have used elsewhere; password lists from past data breaches are the first thing crackers try.
Whoever you send the file to needs the password through a separate channel. Email is usually fine for moderately sensitive content if the password goes by text or a different mailbox. For genuinely sensitive material (legal disclosure, medical records, source-protected journalism), use a password-manager-generated string and an encrypted messaging app like Signal.
Privacy and What 'Browser-Only' Means Here
All encryption happens in your browser using pdf-lib. The PDF and the password never leave your device. That distinction matters: services that upload your file to encrypt it have, by definition, seen the unencrypted contents. For an NDA-bound document or a contract under negotiation, that is unacceptable. The trade-off is that browser-based encryption is slower than a desktop tool for very large files; expect a few seconds per hundred pages on a laptop, longer on a phone.
After protecting, follow up with [Flatten PDF](/flatten-pdf) if you want to lock down form fields too. To restrict editing while keeping the file open without a password, just enable the permission flags without setting a strong password (note: this is much weaker, since users can usually remove permission-only restrictions easily).
Frequently Asked Questions
Is the encryption strong enough for confidential documents?
AES-256 is genuinely strong; the weakness is the password, not the algorithm. With a long random passphrase, the file is secure against any realistic attack short of state-actor resources. With a weak password ('Password1', 'Welcome123'), it can be broken in seconds. The tool's strength is only as good as the secret you choose.
Can I remove the password later?
Yes, if you have the password. Open the file in a PDF editor, enter the password, and save an unprotected copy. The browser-based tool cannot remove a password it does not know, since the file is genuinely encrypted, not just 'flagged' as protected.
What is the difference between user and owner passwords?
A user password is required to open the file at all. An owner password lets the holder change permissions (printing, copying, editing) but does not block opening. Most consumer use cases want a user password for true confidentiality. The tool here sets owner-password style restrictions; for a full open-password lock, you would need a different workflow.
Will printing or copying restrictions actually stop a determined recipient?
Not really. Permission-only restrictions (without a strong open password) can be bypassed in minutes with widely available tools, since the file content is not encrypted, only flagged. They are a deterrent for casual users, not a real barrier. For documents where unauthorised copying matters, use a strong user password instead.
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