how to randomize (scample) regions in a an (org) buffer

[Uwe Brauer]

Hi

I need to replace private information in my org files, but only region wide.

I found 
https://www.reddit.com/r/emacs/comments/6pc0ts/sanitize_buffer_by_replacing_words_with_random/

Where two such functions are discussed, one is even for org files,
however only buffer wide and the code looks rather complicated to me.

Anybody knows about such a function?

Thanks 

Uwe Brauer