It was on [nostr](https://snort.social/e/note1rqsp4klhk7k5nkq02jnje7zeh30ju4wlth27v69x4xmweh9vesmqgczdya). The discussion was mentioned in the Github issue:
https://github.com/nostr-protocol/nips/issues/107#issuecomment-1462875390

I recall nostr folks having discussed signal at some point. I don't recall where but probably worth searching around for it a bit.

k00b

Also take a look at the [SimpleX chat](https://simplex.chat/) protocol. It manages to do encrypted chat in a way that doesn't even involve any kind of identifiers

scottathan

Daily discussion thread

saloon

Just listened to SNL. At the end, the issues with nostr DMs and no encrypted group messages at all was mentioned and that a cryptographer needs to jump in and fix things there.

I think I am going to take a deeper look at the [Signal protocol](https://github.com/signalapp/libsignal). It seems to be the industry standard regarding encrypted communications.

Would be awesome if nostr could be as secure as Signal in the future. 