A question about PDF SecurityHandler initialization

Q: I found in your examples using of InitSecurityHandler() when
opening documents, Do I need to use this method whenever I open a PDF
file, or only when I open a PDF for reading? What happens if I don't
use this method at all?

When Do I need to use RemoveSecurity() method?
A: You can always call this method doc.InitSecurityHandler() after
opening a PDF document (even if the document is not secured). If you
don’t call this method and document is encrypted, you may run into
errors (e.g. grbage data or exceptions) while accessing encrypted
parts of the file.

When Do I need to use RemoveSecurity() method?

This method is only useful if you are planning to remove security from
existing PDF documents (e.g open a secured PDF, remove security and
permissions, then save the file without encryption).