Can you point to any sources to learn more about this phenomenon?

https://cryptome.org/2012/07/gent-forum-spies.htm

Same here, with the reply!

As it happens, I had that link saved before, but have not had a chance to really dig in to it.

But the high quality nature of its contents is immediately apparent, so it's near the top of that particular backlog.

Thanks for the reminder of its existence.