As of Sept 30 2013, Xabber added Orbot support. This is a huge win for chat security. (Gibberbot has done this for a long time, but it isn’t as user-friendly or pretty as Xabber and it is hard to convince people to use it).
The combination of Xabber and Orbot solves the three most critical problems in chat privacy: obscuring what you say via message encryption, obscuring who you’re talking to via transport encryption, and obscuring what servers to subpoena for at least the last information by onion routing. OTR solves the first and Tor fixes the last two (SSL solves the middle one too, though Tor has a fairly secure SSL ciphersuite, who knows what that random SSL-enabled chat server uses – “none?”)
There’s a fly in the ointment of all this crypto: we’ve recently learned a few entirely predictable (and predicted) things about how communications are monitored:
1) All communications are captured and stored indefinitely. Nothing is ephemeral; neither a phone conversation nor an email, nor the web sites you visit. It is all stored and indexed should somebody sometime in the future decide that your actions are immoral or illegal or insidious or insufficiently respectful this record may be used to prove your guilt or otherwise tag you for punishment; who knows what clever future algorithms will be used in concert with big data and cloud services to identify and segregate the optimal scapegoat population for whatever political crises is thus most expediently deflected. Therefore, when you encrypt a conversation it has to be safe not just against current cryptanalytic attacks, but against those that might emerge before the sins of the present are sufficiently in the past to exceed the limitations of whatever entity is enforcing whatever rules. A lifetime is probably a safe bet. YMMV.
2) Those that specialize in snooping at the national scale have tools that aren’t available to the academic community and there are cryptanalytic attacks of unknown efficacy against some or all of the current cryptographic protocols. I heard someone who should know better poo poo the idea that the NSA might have better cryptographers than the commercial world because the commercial world pays better, as if the obsessive brilliance that defines a world-class cryptographer is motivated by remuneration. Not.
But you can still do better than nothing while understanding that a vulnerability to the NSA isn’t likely to be an issue for many, though if PRISM access is already being disseminated downstream to the DEA, it is only a matter of time before politically affiliated hate groups are trolling emails looking for evidence of moral turpitude with which to tar the unfaithful. Any complacency that might be engendered by not being a terrorist may be short lived. Enjoy it while it lasts.
And thus (assuming you have an Android device) you can download Xabber and Orbot. Xabber supports real OTR, not the fake-we-stole-your-acronym-for-our-marketing-good-luck-suing-us “OTR” that Google hugger-muggers and carom–shotts you into believing your chats are ephemeral with (of course they and all their intelligence and commercial data mining partners store your chats, they just make it harder for your SO to read your flirty transgressions). Real OTR is a fairly strong, cryptographically secured protocol that transparently and securely negotiates a cryptographic key to secure each chat, which you never know and which is lost forever when the chat is over. There’s no open community way to recover your chat (that is, the NSA might be able to but we can’t). Sure, your chat partner can screen shot or copy-pasta the chat, but if you trust the person you’re chatting with and you aren’t a target of the NSA or DEA, your chat is probably secure.
But there’s still a flaw. You’re probably using Google. So anyone can just go to Google and ask them who you were chatting with, for how long, and about how many words you exchanged. The content is lost, but there’s a lot of meta-data there to play with.
So don’t use gchat if you care about that. It isn’t that hard to set up a chat server.
But maybe you’re a little concerned that your ISP not know who you’re chatting with. Given that your ISP (at the local or national level) might have a bluecoat device and could easily be man-in-the-middling every user on their network simultaneously, you might have reason to doubt Google’s SSL connection. While OTR still protects the content of your chat, an inexpensive bluecoat device renders the meta information visible to whoever along your coms path has bought one. This is where Tor comes in. While Google will still know (you’re still using Google even after they lied to you about PRISM and said, in court, that nobody using Gmail has any reasonable expectation of privacy?) your ISP (commercial or national) is going to have a very hard time figuring out that you’re even talking to Google, let alone with whom. Even the fact that you’re using chat is obscured.