Android 2.3+: Secure chat program from F-droid

Question

I am looking for a secure chat program that:

• Works on Android 2.3+
• Is available in F-droid or as APK (Available on Google Play is not enough)
• Is compatible between versions
• Is under a free (as freedom) license
• Is as easy to setup as RedPhone (but it is even better if it does not require a phone number, as it will only be used over wifi)

Why not TextSecure? I hear you ask. Because the only APK for Android 2.3 I have found (http://www.appsapk.com/textsecure-private-sms-mms/) is incompatible with newer versions of TextSecure.

If you point to an APK and not an app on F-droid, please also link to the license, so it is clear that is is under a free (as freedom) license.

Answer 1

I installed Chatsecure. Man, that is good!

• Works on Android 2.3: Yes
• Requires Google Play: No
• Compatible between the versions I tested.
• License: https://chatsecure.org/about/ (GPLv3+/iPhone) (Apache/Android)
• Ease of setup: Easier than RedPhone, you do not need a SIM-card. Just create a new account by entering desired username and password.

Bonus points for:

• Facebook chat account. So you can chat with your Facebook friends (and maybe convince them to install ChatSecure, so you can talk encrypted without Facebook listening in).
• Verification of keys is well done.
• It works over Tor if you have OrBot installed.

Answer 2

In addition to ChatSecure (answered above) you might investigate Xabber. The current version requires Android 4.0 and is available on F-droid. The software is open source and license is GPLv3. It's also available as APK from the F-droid site.

The older version, Xabber Classic, runs on Android 2.3 and is supposed to be "coming soon" to F-droid.