Protect PDF
Add password protection and set permissions on your PDF
Add password protection to a PDF, with a user password required to open it and optional restrictions on printing, copying, or editing.
How It Works
How Protect PDF Works
The PDF is first rebuilt page-by-page to produce a clean base document, then standard PDF encryption (RC4, 40-bit, the PDF "Standard Security Handler" revision 2) is applied to every stream in the file using keys derived from your chosen password.
You can set a "user password" (required simply to open the file) and optionally a separate "owner password" that controls permissions — whether the document can be printed, copied, or modified without that password.
Permission flags are embedded in the encryption dictionary per the PDF specification, so compliant PDF readers will honor restrictions like "printing disabled" even if the user password is entered correctly.
Worked Example
See It In Action
Uploading a contract PDF with a user password of "contract2026" and printing disabled produces a file that requires that password to open in any PDF reader, and blocks printing even after the correct password is entered.
FAQ
Frequently Asked Questions
What's the difference between the user and owner password?
The user password is required just to open the file. The owner password (if set) controls permissions like printing and copying — someone with the user password can view the document, but restricted actions require the owner password.
How strong is this encryption?
This tool uses the standard PDF 40-bit RC4 encryption (security handler revision 2), which is broadly compatible with all PDF readers. For documents needing stronger, modern encryption standards, check whether your reader/workflow supports 256-bit AES instead.
Can I remove the password later?
Yes — use the Unlock PDF tool with the correct password to produce an unprotected copy whenever you need to remove the restriction.
Will restrictions like "no printing" always be respected?
Permission flags are honored by compliant PDF readers, but they are a deterrent rather than an absolute technical barrier — determined users with certain tools can sometimes bypass permission-only restrictions. For fully sensitive documents, rely on the open password, not permission flags alone.
