PDF security settings control two distinct aspects: document access and document permissions. The open password prevents unauthorized users from viewing the document at all. The permissions password controls what authorized viewers can do.
Encryption strength options include 128-bit AES and 256-bit AES. The 256-bit option is recommended for sensitive documents and is compatible with Adobe Reader 10 and later. Legacy 40-bit and 128-bit RC4 options are available for backward compatibility.
Permission controls allow granular restriction of printing (none, low resolution, high resolution), content copying, form filling, annotation, page extraction, and document assembly. These restrictions are enforced by compliant PDF readers.
Certificate-based encryption allows specifying individual recipients who can open the document using their digital certificates. This method avoids the need to share passwords and supports asymmetric encryption workflows.
Batch encryption processes multiple files with the same security settings. A summary report lists each file with its applied settings and encryption status.