What are the most private chat applications?

@DavidBond Do you accept hardware apps? Because two cups and a bit of string is secure AF.

@LouisIngenthron @DavidBond
Developing your own writing system with regular changes to differing factors each iteration and sending it via carrier pigeon with invisible ink with a false message on top would be better.

@lucifargundam @DavidBond Well, yeah, of course. I've been doing a variation on that for years (who doesn't?), but the efficiency isn't great, so I'm experimenting with strapping model rockets to the pigeons' backs.