Bank statements, copies of ID cards, payslips and medical results often travel by email. Emails can be forwarded, intercepted or sent to the wrong person. A password turns your PDF into a locked file that is useless to anyone who doesn't have the key.
How PDF encryption works
When you protect a PDF with PDFly, the whole content is encrypted with AES-256, the strongest algorithm defined in the PDF standard. PDF readers such as Adobe Acrobat, Chrome, Edge and phone viewers ask for the password before showing anything. Without it, the file is unreadable.
Step by step
- Open Protect PDF and add your file.
- Type a strong password twice.
- Choose whether printing is allowed.
- Press Protect PDF and download the encrypted copy.
- Open it once yourself to check the password works.
Choosing a good password
- Use at least 10 characters, mixing letters, numbers and a symbol.
- A short phrase is easy to remember and hard to guess: Blue-Tea-Oran-2026!
- Avoid birth dates, phone numbers and names — they are the first things attackers try.
Sending the password safely
Never write the password in the same email as the file. Send the PDF by email and the password by SMS or a phone call. That way, someone who gets access to the email still can't open the document.
What protection does not do
- It cannot stop someone who has the password from taking a screenshot or printing a copy.
- If you forget the password, the file cannot be recovered. Keep the unprotected original somewhere safe.
Extra layer: add a watermark such as “Copy for Bank X only — September 2026” with Watermark PDF. If the document leaks, it can't easily be reused elsewhere.