App Pick: Signal Private Messenger
The winner of the App Arena from All About Android 297 is Signal Private Messenger. This is an app for encrypted messages with the ability to have group chats. It uses your existing phone number and address book, and there's no separate logins, usernames, passwords, or PINs. It's also free and open source, enabling anyone to verify its security by auditing the code.
Not only does Signal encrypt all the messages in group conversations, but the Signal server never even has access to the group metadata like hte membership list. It's also designed to be fast, even in the most constrained environments.