The best recommendation I have at the current time is OTR https://en.wikipedia.org/wiki/Off-the-Record_Messaging, authenticate your key fingerprints, ensure that neither party's chat program is logging, and that both computers are free of malware.
Pidgin supports OTR, but it crashes enough to raise concerns about that last point.
I'm confused. The above poster asked what a good chat program is for communicating with other people (namely non-technical users) where the user can't get spied upon.
This isn't so much a "how can I be secure" question, but a "what alternatives to Skype do I have that work on Linux" question.
Which is one I'm also interested in, since I also want something thats (1)linux compatible, (2) easy and accessible for "average users" of any OS, (3) and secure. And I'm hoping for those things in that order.
If you are talking to an average user (implied by #2), then there are short odds that at some point their machine will be compromised, at which point it doesn't matter how secure the communications channel is.
I should clarify, I don't mean secure from all angles. In terms of security I don't want a company looking through my chat logs, and I don't want someone who be able to see what I'm saying via a wifi sniffer.
Pidgin supports OTR, but it crashes enough to raise concerns about that last point.