[0xFEE1DEAD]

A public chat - like one that anyone can join at any time without needing an invitation?

If so, then you really don't need any extra encryption.

If not, then it depends on who's using your chat, how they use it, and for what purpose. Are the users of the chat room a small group with occasional users joining or leaving, or are many users expected to join and leave at any given moment?

That being said, encrypting the notifications won't bring any real benefits. A bad actor would simply focus on trying to compromise your server.

If you do decide that full e2ee would benefit your users, then look for someone who can help you implement it.

Implementing real e2ee for a 2 party chat is hard for someone without experience.

Implementing e2ee for a group chat is hard even for someone with experience.

[tonyhart7]

welp, I am just gonna look at Telegram/Signal source and make a lite version for it

[mort96]

I don't think you want to look at the source code, and I don't think you want to look at Telegram. You should have a look at the Signal Protocol: https://en.m.wikipedia.org/wiki/Signal_Protocol. It's well documented. Maybe there are libraries which implement it.

(Though I still think that "how can I protect against TLS being broken?" is the wrong question and you should instead ask "how can I ensure that TLS doesn't break?".)