Late Soviet Union might be a similar to what you are looking for? I wasn’t alive back then, but from what I recall from reading old science magazines as a kid, there were few home computers, lots of “radio-hobbyist” stuff (DIY electronics from radio to computers), and praise for “inventor and rationalizer” for the good of the people. On paper at least. I think most interpersonal communication was over the phone or amateur radio, or even telegrams.

I don’t know much about how modern China goes about it though.

But TBF it’s very difficult to speculate about message encryption. Thinking back from my own experience, digital communication (over the internet or even SMS over cell phone networks) was not common until 90s-2000s, and encrypting them became a concern not too long ago, early 2010s I think? Before that, it was HTTP (without the S) and unencrypted AIM chats over the Jabber protocol.