I was working on a data classification project a few months ago, and one of systems that needs to be classified is Confluence. The data on Confluence can be Public, Internal, Protected and Highly Protected.
I designed a solution to use Comala workflow which we have purchased already, so no more extra cost on software. The design principle are:
- Data should be classified per page.
- Classification should be associated with right permission settings.
Here is a example.
A public page has no restrictions.

Now, let me re-classify it to Protected.

Noticed the difference after re-classification?

Now only confluence-power-users can view and edit this page.

The sample code can be found in my gist.
You could also use the set-restriction macro in lieu of removing to clear and then setting anew.
Comala suggests this approach with the following statement:
“Using {set-restrictions} helps avoid permissions errors in the interim period between clearing permissions and adding new permissions.”
https://wiki.comalatech.com/display/CWL/set-restrictions+macro
Thanks for sharing! Before doing it, just be aware of that it ONLY removes any existing permissions of that type.