- Drag it in, choose it, or paste it. It is read here in the tab and never uploaded.
- The settings column holds 4 controls for this tool. The defaults suit most files.
- “Protect PDF” works on your device, then Original and Result sit side by side with a download.
About Protect PDF
Protect PDF encrypts a document with AES-256 behind a password you set, and decides what a reader may still do with it: print it, copy the text, add comments or fill in fields.
The password you set encrypts the document with AES-256, which is real encryption rather than a flag a reader is asked to respect: without the password there is nothing to read. A separate owner password is generated at random and kept by nobody, which is what stops the permissions being lifted by anyone who happens to know the usual default.
Permissions are the softer half. Printing, copying text, commenting and filling in fields are each allowed or refused, and well-behaved readers obey. They are a statement of intent inside an encrypted file, not a second lock — someone who can open the document can eventually get the text out of it.
Passwords here are limited to ordinary printable characters, and the reason is practical: readers disagree about how to normalize accented and non-Latin characters in an AES-256 password, so a password with them in would open the file in some applications and not in others. Eight characters is the minimum; a passphrase is better than a short complicated word.