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Add password protection to PDF files online for free. Set user and owner passwords with AES-256 encryption. 100% browser-based, your files never leave your device.
PDF password protection encrypts a PDF document so that a password is required to open, print, or modify it, using standard encryption algorithms defined in the PDF specification (ISO 32000).
Drop a PDF file here or click to browse
All processing happens in your browser. Your passwords are never sent anywhere.
| Feature | User Password | Owner Password |
|---|---|---|
| Purpose | Open the PDF | Control permissions |
| Required to view | Yes | No |
| Controls printing | No | Yes |
| Controls copying | No | Yes |
| Most common | Yes | Less common |
Formula
Encrypted PDF Size ≈ Original Size + Encryption OverheadOriginal Size = File size of the unencrypted PDF in bytes
Encryption Overhead = Additional bytes for encryption metadata, typically 1–5 KB depending on encryption method and key length
Worked Example
Encrypting a 5 MB PDF document
Did you know? PDF encryption has been part of the PDF specification since version 1.1 (1994). Modern PDFs support AES-256 encryption, the same standard used by governments for classified information (source: ISO 32000-2:2020).
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