Lock a PDF with a password to restrict access
1 min read·25 July 2026
Need to send a confidential PDF that only the right person can open? PDFrust adds AES password encryption to any PDF directly in your browser — nothing is uploaded to any server.
How PDF password protection works
PDF password protection uses AES encryption (128-bit or 256-bit) to scramble the document content. Without the correct password, the PDF cannot be opened in any viewer. This encryption is part of the PDF standard and is universally supported.
Set a password with PDFrust
Open the protect tool, upload your PDF, enter a strong password, and confirm it. Click "Protect" — the encrypted PDF downloads immediately. Always send the password via a separate channel (e.g. SMS or phone call), never in the same email as the file.
Unlock PDF
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Opening password vs. permissions password
PDFs support two types of passwords: an opening (user) password encrypts the file — the recipient needs it just to open the document. A permissions (owner) password allows opening but restricts printing, copying, or editing. PDFrust uses an opening password for maximum security.
Forgot the password?
If you forget the password, the document is effectively inaccessible — that's the point of encryption. Always store passwords in a password manager. If you need to remove a password from your own protected PDF, use the unlock tool.
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