Android Chat For Private session for users ( Development Workflow)

Question

I am developing Android Application for Chat between two users as private session.

Android application would be Android 2.0 and above .
If any user wants to chat then he can enter any email to chat and session between two users will be private and can able to store in database.
Other user should not be able to watch the private sesion.
if any one answer about android application where it will be connected to web server (php) then good for me to understand .
So if any one known the develpoment flow please suggest here .

Please don't suggest about IRC Chat where all user combined in same open template.

Answer 1

You could use an XMPP server and use for instance asmack library for android.

Tutorials about the android application: http://davanum.wordpress.com/2007/12/31/android-just-use-smack-api-for-xmpp/

There are several different servers out there. For instance OpenFire. http://www.igniterealtime.org/projects/openfire/

Answer 2

If sounds like what you want is an XMPP server with client to client encryption.

Here are a list of XMPP server options: http://xmpp.org/xmpp-software/servers/

Here is a discussion on various XMPP libraries to use with Android: Android and XMPP: Currently available solutions

As for the encryption, it looks like you want to mimic what OTR does (for pidgin). The description of how the protocol works is posted here: http://www.cypherpunks.ca/otr/Protocol-v2-3.1.0.html

You can also grab their source code from here: http://www.cypherpunks.ca/otr/index.php#downloads (warning: code is written in C)