Updated on
Sending a payslip, a medical report or a contract? Then you want only the recipient to be able to open it. A password encrypts the PDF: without that password, the contents can’t be read. Setting it takes a minute. Choosing a good password and getting it safely to the recipient deserves a bit more thought.
Protect the PDF in three steps
- Open Protect PDF and choose your file.
- Type your password twice. That way a typo can’t lock you out.
- Click Protect PDF and download the protected file.
The PDF is encrypted with AES-256, the strongest encryption in the PDF standard. Your file and your password stay in your browser.
Choose a good password
The encryption is only as strong as the password. A short or predictable password can be guessed by trying many options automatically.
- Make it long: four or five unrelated words, such as “lamp river seven orange”, are stronger and easier to type than a short code with symbols.
- Don’t use information about the recipient, such as a date of birth or a client number. Others may know it too.
- Use a different password per file or recipient, not the same one you use for your email or bank.
- Keep it somewhere safe, for example in a password manager. A forgotten password can’t be recovered, not even by us.
Share the password safely
A password that travels in the same email as the file protects very little: anyone who can read that email has both.
- Use a different channel: email the PDF and send the password by text message, or tell it by phone.
- Agree on it in advance with people you send files to regularly, so you don’t have to send a password each time.
- Don’t put the password in the file name or in the subject line.
What a password does and doesn’t protect
- It does protect the content: without the password, the pages can’t be read.
- The file name stays visible. Choose a neutral name, such as “document-march.pdf” instead of “medical-report-firstname-lastname.pdf”.
- Once opened, the reader can do anything with it: save, print, forward. The password protects the way there, not what happens afterwards.
- No print or copy locks. Those are only a request to the reader app and are easy to get around, so we don’t add them.
A PDF often contains an author name, the program used and dates. Remove that first with Remove metadata, then protect the clean file.
Changing or removing a password
Want to change the password of a protected PDF? First remove it with Unlock PDF (you’ll need the current password for that), then protect the file again with the new one.
Frequently asked questions
Can the recipient open the file without special software?
Yes. Current PDF readers and browsers ask for the password and then show the document as usual. Very old readers, from before about 2010, may not open it.
Can I protect several PDFs at once?
Yes. Choose all the files: each one gets the same password, and you download them together as one zip.
Is a protected PDF safe to send by email?
It is a lot safer than an unprotected PDF, as long as the password is strong and you send it through a different channel. No method is perfect: the recipient’s device and what they do with the file afterwards still matter.