Encrypt PDF from Google Docs

PDF encryption scrambles the document content using a cipher. Without the correct password, a PDF reader cannot decode the content and displays nothing useful. The most common encryption standards for PDFs are AES-128 and AES-256. AES-256 is stronger and is the current recommended minimum for documents containing sensitive data. Older standards like 40-bit and 128-bit RC4 are considered weak and should be avoided.

Adobe Acrobat supports AES-256 when you select Acrobat X or later compatibility. PDF24 Desktop (free, Windows) supports AES-256 in its advanced settings. On Mac, Preview applies AES-128 by default. For AES-256 on Mac without Acrobat, use PDF24 in the browser with the advanced options enabled.

An open password, sometimes called a user password, controls who can view the document. A permissions password, sometimes called an owner password, controls what the viewer can do: print, copy, edit, extract pages. You can set both on the same PDF or just one. For most document sharing scenarios, an open password is sufficient.

Many compliance frameworks reference encryption when addressing secure document handling. HIPAA guidance recommends AES-128 or stronger for protected health information. GDPR does not specify an encryption algorithm but cites encryption as an appropriate technical measure. Legal and financial services firms often have internal policies that specify AES-256. When in doubt, AES-256 covers the most requirements.