How do I use the Action Wizard to restrict editing (to require a password) for an entire folder of unsecured documents without entering the password for each document manually?

I need to convert several thousand .tiff image files of scanned documents into edit-restricted PDF/A format. I'm familiar with the Action Wizard but how can I use the Protect PDF command to require a password for editing without having to enter the password on each document manually? I'm using one master password for all documents.