The PDF format has had a permission system since version 1.1 in 1994. Despite being over 30 years old, PDF permissions remain widely used for controlling document distribution and use.
What permissions you can set
The PDF specification defines several standard permission flags: Printing — whether the document can be printed at all, or only at a reduced quality. Content copying — whether text and images can be selected and copied to the clipboard. Document modification — whether the document structure can be changed. Annotations — whether comments, form field entries, and digital signatures can be added. Form fill — whether existing form fields can be filled even when general modification is restricted.
The owner password requirement
Permission restrictions require an owner password to take effect in the PDF specification. Without an owner password, any PDF reader is technically allowed to ignore the permission flags. When you set permissions with an owner password, the PDF reader must either enforce those permissions or require the owner password to proceed. This is why PurePDF lets you set permission flags independently of the open (user) password.
The honest truth about permission enforcement
Compliant PDF readers — Adobe Acrobat, Preview on macOS, most modern browsers — will honour permission flags. But PDF is an open format, and non-compliant tools designed specifically to remove restrictions will ignore these flags entirely. If someone is motivated to circumvent PDF permissions, they can do so. This does not make permissions useless — they stop casual users from performing restricted actions — but they should not be relied upon as the sole mechanism for protecting truly sensitive content.
Practical permission configurations
For a document you want to share for review but prevent copying: set an owner password, enable viewing, disable content copying and modification, and allow annotations so reviewers can add comments. For a document you want to allow printing but not digital editing: enable printing and viewing, disable modification and content copying. For a PDF form you want users to fill but not modify: enable form fill and printing, disable general modification.
