Protect PDF — Add Password & 128-bit AES Encryption
Add a password to any PDF with 128-bit AES encryption. Optionally set an owner password and restrict printing, copying and editing — all in your browser.
Protect PDF adds a password and industry-standard 128-bit AES encryption to any PDF file, so only recipients who know the password can open it. You can also set an owner password that governs permissions such as printing, copying and modifying — useful when you want the document to be readable but restrict what people can do with it. Every step of the encryption happens locally in your browser using open-source cryptography, so the document never leaves your device.
- User password (required to open the PDF)
- Optional owner password (required to change permissions)
- 128-bit AES encryption (PDF spec v1.6+)
- Optional permissions: printing, copying, modifying, form-filling
- Runs entirely in your browser using @cantoo/pdf-lib
- 1Upload the PDF you want to protect.
- 2Set a user password (required to open) and/or owner password (for permissions).
- 3Choose which permissions to allow.
- 4Press Protect and download the encrypted PDF.
- Use a strong password — at least 12 characters mixing letters, digits and symbols
- Owner password should differ from the user password for real permission control
- Encryption cannot be reversed without the correct password — keep a copy of your password
PDFs support two distinct passwords. The user password is required to open the file at all; without it, the PDF is unreadable. The owner password governs what the recipient can do once they have opened it — things like printing, copying selected text, editing, or filling in forms. Setting only a user password gives you strict access control; setting both lets you distribute a PDF that anyone can read but only trusted users can modify.
Our tool uses @cantoo/pdf-lib, a browser-safe fork of pdf-lib that implements the PDF 1.6+ security handler with 128-bit AES. When you press Protect, the PDF is loaded, the security handler is initialised with your passwords and chosen permissions, and every content stream + string in the file is encrypted before being written back. The output is a fully compliant, encrypted PDF that opens correctly in Adobe Reader, macOS Preview, Chrome, Edge and every other mainstream reader — they will prompt for the password just like they would for any other protected file.
Beyond the password, PDF encryption supports permission flags that reader software honours. You can allow or block: printing (high-quality or low-quality), copying text and graphics, modifying the content, filling in forms and adding annotations. These flags are enforced by the reader and are removed once the correct owner password is entered.
The encryption happens entirely inside your browser tab. Your PDF is never uploaded, the passwords never leave your device, and closing the tab wipes every working buffer. This makes Protect PDF safe to use on sensitive material such as contracts, financial reports and HR documents that must never touch a third-party server.
Your files never leave your browser. All parsing, page rendering and PDF assembly happens locally on your device using open-source libraries (pdf-lib and pdf.js). ilovedigital.in cannot see, store or share the contents of your documents.
Frequently asked questions
Common questions about the Protect PDF — Add Password & 128-bit AES Encryption tool and how your data is handled.
Can the password be recovered later?
Which encryption standard is used?
Do permission flags really stop copying?
Are my files uploaded?
Can I encrypt a PDF/A document?
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