How-To

Password Protect Your PDF Files

April 20, 2025·4 min read

Password-protecting a PDF adds a layer of security that prevents unauthorized access to sensitive documents. Whether you are sharing financial reports, legal contracts, or personal records, encryption ensures only intended recipients can open and read the file. Here is how to lock down your PDFs properly.

Two types of PDF passwords

PDFs support two levels of password protection. An open password prevents anyone from viewing the document without entering the correct password. A permissions password restricts specific actions like printing, copying text, or editing, while still allowing the document to be viewed. You can use either one or both for maximum security.

Choosing strong passwords

Use at least 12 characters with a mix of uppercase, lowercase, numbers, and symbols. Avoid dictionary words, birthdates, and common patterns. A passphrase like three random words joined with numbers is both strong and memorable. Never reuse passwords across different documents or services.

Encryption standards

Modern PDF encryption uses AES-256, which is virtually uncrackable with current technology. Older PDFs may use RC4 or AES-128, which are weaker. When protecting sensitive documents, choose AES-256 encryption where your tool offers it, and a long password.

Protect PDFs with SquishConvert

Upload your PDF to SquishConvert, set an open password, and download the protected file. The encryption is done by our provider CloudConvert, which deletes the file and the password after processing, within 24 hours at most. Available with SquishConvert Pro.