PDF tool
Protect PDF with AES-256
Add AES-256 password protection to a PDF using a confirmed password and a local WebAssembly worker.
Your file never leaves your device.
Simple steps
How it works
- 01
Choose the PDF you want to protect.
- 02
Enter a strong password, review its strength hint, and confirm it.
- 03
Apply AES-256 protection and download the encrypted PDF.
Good to know
Frequently asked questions
What encryption does this tool use?
The qpdf engine writes a PDF using 256-bit AES encryption.
Why does the form ask me to confirm the password?
The confirmation catches typing mistakes before the file is encrypted. File ICU cannot recover a forgotten password.
Are PDF contents uploaded?
No. The PDF and password are passed to a local WebAssembly worker in your browser.
Can a recipient open the PDF without the password?
No. They need the password to open it. Send that password through a separate trusted channel.
Does this change my original file?
No. The encrypted document is a new download; your chosen source remains untouched.