Bleep by BitTorrent is an encrypted Messaging app and available for all major Operating Systems.
Whisper function deletes the chat on both devices once you or the other party closes the window.
Conclusion: It's a great messenger with a lot of features. Unfortunately it's closed source from what I can tell which is a big fat minus on the trust index.
If you want to test it, feel free to add me: d1cec5440623b8eb4d2415522bf341d2b1c0dcbb319fe0004df142a4175d0545
